Appearance
| 1 | namespace Syntax.Process is | |
| 2 | use Logging | |
| 3 | use Source | |
| 4 | use Ghul.Disposable | |
| 5 | ||
| 6 | use Semantic.Types.Type | |
| 7 | use Semantic.LEAST_UPPER_BOUND_MAP | |
| 8 | ||
| 9 | use IR.Values | |
| 10 | ||
| 11 | // An operator or index expression whose operand walks are held | |
| 12 | // under a speculation because an operand takes its type from | |
| 13 | // context and has none to offer resolution. `retried` records that | |
| 14 | // the resolved formal type has been pushed in and the operand | |
| 15 | // walked again, so that happens once however the second walk turns | |
| 16 | // out. | |
| 17 | class DEFERRED_OPERANDS(node: Trees.Node) is | |
| 18 | retried: bool public | |
| 19 | si | |
| 20 | ||
| 21 | // Compiles unary, binary and index expressions. Split out of | |
| 22 | // COMPILE_EXPRESSIONS, which delegates visit(unary), pre(binary), | |
| 23 | // visit(binary) and visit(index) here. The exception-handling | |
| 24 | // wrappers of visit(binary) / visit(index) stay on the visitor; | |
| 25 | // visit_binary / visit_index are the enclosed logic. | |
| 26 | class COMPILE_OPERATORS is | |
| 27 | _deferred_operands: Collections.LIST[DEFERRED_OPERANDS] field | |
| 28 | ||
| 29 | _logger: Logger | |
| 30 | _symbol_table: Semantic.SYMBOL_TABLE | |
| 31 | _innate_symbol_lookup: Semantic.Lookups.InnateSymbolLookup | |
| 32 | _overload_resolver: Semantic.OVERLOAD_RESOLVER | |
| 33 | _symbol_use_locations: Semantic.SYMBOL_USE_LOCATIONS | |
| 34 | _function_caller: Semantic.FUNCTION_CALLER | |
| 35 | _calls: COMPILE_CALLS | |
| 36 | _flow: NARROWING_FLOW | |
| 37 | _condition_analyzer: CONDITION_ANALYZER | |
| 38 | _visitor: COMPILE_EXPRESSIONS | |
| 39 | _value_boxer: IR.VALUE_BOXER | |
| 40 | _range_slice_resolver: Semantic.RANGE_SLICE_RESOLVER | |
| 41 | ||
| 42 | init( | |
| 43 | logger: Logger, | |
| 44 | symbol_table: Semantic.SYMBOL_TABLE, | |
| 45 | innate_symbol_lookup: Semantic.Lookups.InnateSymbolLookup, | |
| 46 | overload_resolver: Semantic.OVERLOAD_RESOLVER, | |
| 47 | symbol_use_locations: Semantic.SYMBOL_USE_LOCATIONS, | |
| 48 | function_caller: Semantic.FUNCTION_CALLER, | |
| 49 | calls: COMPILE_CALLS, | |
| 50 | flow: NARROWING_FLOW, | |
| 51 | condition_analyzer: CONDITION_ANALYZER, | |
| 52 | visitor: COMPILE_EXPRESSIONS | |
| 53 | ) is | |
| 54 | super.init() | |
| 55 | ||
| 56 | _logger = logger | |
| 57 | _symbol_table = symbol_table | |
| 58 | _innate_symbol_lookup = innate_symbol_lookup | |
| 59 | _overload_resolver = overload_resolver | |
| 60 | ||
| 61 | _range_slice_resolver = | |
| 62 | Semantic.RANGE_SLICE_RESOLVER( | |
| 63 | innate_symbol_lookup, | |
| 64 | overload_resolver, | |
| 65 | function_caller, | |
| 66 | logger) | |
| 67 | _symbol_use_locations = symbol_use_locations | |
| 68 | _function_caller = function_caller | |
| 69 | _calls = calls | |
| 70 | _flow = flow | |
| 71 | _condition_analyzer = condition_analyzer | |
| 72 | _visitor = visitor | |
| 73 | _value_boxer = IR.VALUE_BOXER(logger) | |
| 74 | _deferred_operands = Collections.LIST[DEFERRED_OPERANDS]() | |
| 75 | si | |
| 76 | ||
| 77 | visit_unary(unary: Trees.Expressions.UNARY) is | |
| 78 | unary.compile_expressions_state.value = null | |
| 79 | ||
| 80 | if unary.right.value? then | |
| 81 | // An operand with no type has nothing for overload | |
| 82 | // resolution to match against, and every consumer below | |
| 83 | // reads the type as though it were there. | |
| 84 | if !unary.right.value.type? then | |
| 85 | unary.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), unary.location) | |
| 86 | return | |
| 87 | fi | |
| 88 | ||
| 89 | let right_value = unary.right.value | |
| 90 | ||
| 91 | let function_group = | |
| 92 | _static_operator_candidates( | |
| 93 | unary.operation.location, | |
| 94 | unary.operation.name, | |
| 95 | Collections.LIST[Type]([right_value.type!]) | |
| 96 | ) | |
| 97 | ||
| 98 | if !function_group? then | |
| 99 | if | |
| 100 | _defer_on_unsettled_operand( | |
| 101 | unary, | |
| 102 | unary.operation.location, | |
| 103 | right_value.type, | |
| 104 | null | |
| 105 | ) | |
| 106 | then | |
| 107 | return | |
| 108 | fi | |
| 109 | ||
| 110 | _logger.error(unary.operation.location, "no unary operator {unary.operation} found") | |
| 111 | ||
| 112 | unary.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), unary.location) | |
| 113 | return | |
| 114 | fi | |
| 115 | ||
| 116 | // FIXME: this doesn't seem right | |
| 117 | let want_instance = right_value.is_consumable | |
| 118 | ||
| 119 | let argument_values = Collections.LIST[Value]([right_value]) | |
| 120 | let argument_types = Collections.LIST[Type]([right_value.type!]) | |
| 121 | let argument_expressions = Collections.LIST[Trees.Expressions.Expression]([unary.right]) | |
| 122 | ||
| 123 | let (overload_result, errors) = | |
| 124 | _resolve_with_retry( | |
| 125 | unary.location, | |
| 126 | function_group, | |
| 127 | argument_values, | |
| 128 | argument_types, | |
| 129 | argument_expressions, | |
| 130 | want_instance, | |
| 131 | unary | |
| 132 | ) | |
| 133 | ||
| 134 | if overload_result == null then | |
| 135 | if | |
| 136 | _defer_on_unsettled_operand( | |
| 137 | unary, | |
| 138 | unary.operation.location, | |
| 139 | right_value.type, | |
| 140 | null | |
| 141 | ) | |
| 142 | then | |
| 143 | return | |
| 144 | fi | |
| 145 | ||
| 146 | if errors? /\ errors.count > 0 then | |
| 147 | _logger.merge(errors) | |
| 148 | fi | |
| 149 | ||
| 150 | unary.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), unary.location) | |
| 151 | return | |
| 152 | fi | |
| 153 | ||
| 154 | let function = overload_result.function | |
| 155 | ||
| 156 | if function.is_unsafe_constraints then | |
| 157 | _logger.warn(unary.location, "unchecked-constraints", "call to {function} has unchecked constraints") | |
| 158 | fi | |
| 159 | ||
| 160 | _symbol_use_locations.add_symbol_use(unary.operation.location, function) | |
| 161 | ||
| 162 | let value = function.call(unary.location, null, argument_values, null, _function_caller) | |
| 163 | ||
| 164 | unary.compile_expressions_state.value = value | |
| 165 | fi | |
| 166 | si | |
| 167 | ||
| 168 | // Resolve an operator overload with the same constraint-push | |
| 169 | // retry sequence visit_call uses: initial type-based resolve, | |
| 170 | // then on null or PARTIAL re-walk function-literal operands | |
| 171 | // with the chosen formal pushed as expected_type so a lambda | |
| 172 | // whose parameter type was unknown on the first walk can | |
| 173 | // infer it from the operator's signature. | |
| 174 | // | |
| 175 | // Operates inside its own speculation snapshot: the retry's | |
| 176 | // re-walks update operand `.value` fields in place but the | |
| 177 | // logger diagnostics from speculation are scrubbed when the | |
| 178 | // snapshot backtracks, matching the visit_call pattern. | |
| 179 | _resolve_with_retry( | |
| 180 | location: Source.LOCATION, | |
| 181 | function_group: Semantic.Symbols.FUNCTION_GROUP, | |
| 182 | argument_values: Collections.LIST[Value], | |
| 183 | argument_types: Collections.LIST[Type], | |
| 184 | argument_expressions: Collections.List[Trees.Expressions.Expression], | |
| 185 | want_instance: bool, | |
| 186 | cache_key: Trees.Node | |
| 187 | ) -> (Semantic.OVERLOAD_RESOLVE_RESULT?, Logging.DIAGNOSTICS_STATE?) is | |
| 188 | RETRY_SITE_STATS.note("operators.resolve_with_retry") | |
| 189 | let use logger_snapshot = _logger.speculate_then_backtrack() | |
| 190 | ||
| 191 | // Operator operands walk during ordinary tree descent, so | |
| 192 | // the baseline captured here is the env after that walk; a | |
| 193 | // retry re-walk resets to it through `_flow.restore()`, and | |
| 194 | // the whole attempt rolls the env back on exit — the operand | |
| 195 | // values are already set, only the diagnostics matter. | |
| 196 | let use flow_speculation = _flow.speculate_then_roll_back() | |
| 197 | ||
| 198 | let overload_result mut = | |
| 199 | _overload_resolver.resolve( | |
| 200 | location, | |
| 201 | function_group, | |
| 202 | argument_types, | |
| 203 | false, | |
| 204 | want_instance, | |
| 205 | false | |
| 206 | ) | |
| 207 | ||
| 208 | if !overload_result? then | |
| 209 | let retry = _calls.try_overload_after_null( | |
| 210 | function_group, | |
| 211 | argument_values, | |
| 212 | argument_types, | |
| 213 | want_instance, | |
| 214 | null, | |
| 215 | argument_expressions, | |
| 216 | location, | |
| 217 | cache_key | |
| 218 | ) | |
| 219 | ||
| 220 | if retry? then | |
| 221 | overload_result = retry | |
| 222 | fi | |
| 223 | fi | |
| 224 | ||
| 225 | if overload_result? /\ overload_result.needs_retry then | |
| 226 | let retry = _calls.try_overload_on_partial( | |
| 227 | overload_result, | |
| 228 | function_group, | |
| 229 | argument_values, | |
| 230 | argument_types, | |
| 231 | want_instance, | |
| 232 | null, | |
| 233 | argument_expressions, | |
| 234 | location, | |
| 235 | cache_key | |
| 236 | ) | |
| 237 | ||
| 238 | if retry? then | |
| 239 | overload_result = retry | |
| 240 | fi | |
| 241 | fi | |
| 242 | ||
| 243 | let errors = logger_snapshot.backtrack() | |
| 244 | ||
| 245 | return (overload_result, errors) | |
| 246 | si | |
| 247 | ||
| 248 | pre_binary(binary: Trees.Expressions.BINARY) -> bool is | |
| 249 | // For `/\` / `\/`, walk the operands with the narrowing | |
| 250 | // environment threaded so within-condition narrowing | |
| 251 | // applies as the right operand compiles: in | |
| 252 | // `isa T(x) /\ x.foo`, `x.foo` sees `x` as `T`. The | |
| 253 | // `/\` right walks under the left's true edge, the `\/` | |
| 254 | // right under its false edge. The BINARY as a whole | |
| 255 | // leaves the ambient environment unchanged — the | |
| 256 | // enclosing IF derives the overall narrowing from | |
| 257 | // analyze_condition once the condition is fully walked. | |
| 258 | let op = binary.operation.name | |
| 259 | ||
| 260 | // A null-comparison leaf forms a presence fact from its | |
| 261 | // non-null operand; stamp the log position the test is | |
| 262 | // walked at, so facts formed from it skip the calls that | |
| 263 | // ran before it. Both surface forms walk through a node | |
| 264 | // whose operation name is `==`. | |
| 265 | if op =~ "==" then | |
| 266 | if isa Trees.Expressions.NULL(binary.left) \/ isa Trees.Expressions.NULL(binary.right) then | |
| 267 | _flow.note_test_site(binary) | |
| 268 | fi | |
| 269 | fi | |
| 270 | ||
| 271 | if op =~ "/\\" \/ op =~ "\\/" then | |
| 272 | let saved = _flow.current_env.copy() | |
| 273 | let epoch = _flow.heap_epoch | |
| 274 | let mark = _flow.crossing_mark | |
| 275 | ||
| 276 | binary.left.walk(_visitor) | |
| 277 | ||
| 278 | let left_facts = _condition_analyzer.analyze_condition_facts_only(binary.left, saved) | |
| 279 | ||
| 280 | let right_env = | |
| 281 | if op =~ "/\\" then left_facts.then_env else left_facts.else_env fi | |
| 282 | ||
| 283 | // The right operand's environment derives from the | |
| 284 | // pre-left snapshot; a store during the left's own | |
| 285 | // walk means its heap facts cannot be trusted while | |
| 286 | // the right compiles, and its calls attach as | |
| 287 | // crossings. | |
| 288 | if _flow.heap_killed_since(epoch) then | |
| 289 | right_env.drop_heap_facts() | |
| 290 | else | |
| 291 | _flow.adopt_crossings_since(right_env, mark) | |
| 292 | fi | |
| 293 | ||
| 294 | _flow.set_env(right_env) | |
| 295 | ||
| 296 | binary.right.walk(_visitor) | |
| 297 | ||
| 298 | // Same for the ambient environment restored after | |
| 299 | // the operator: it predates both operand walks. | |
| 300 | if _flow.heap_killed_since(epoch) then | |
| 301 | saved.drop_heap_facts() | |
| 302 | else | |
| 303 | _flow.adopt_crossings_since(saved, mark) | |
| 304 | fi | |
| 305 | ||
| 306 | _flow.set_env(saved) | |
| 307 | ||
| 308 | return true | |
| 309 | fi | |
| 310 | ||
| 311 | // An operand that takes its type from context has none to | |
| 312 | // offer resolution, and reports so as it walks. Open a | |
| 313 | // speculation over the operand walks, the way visit_call | |
| 314 | // does over its argument walks, so that error can be rolled | |
| 315 | // back once resolution has settled on a formal type to push | |
| 316 | // in. The operands still walk in their ordinary order and | |
| 317 | // through the ordinary walker — only the diagnostics are | |
| 318 | // held. | |
| 319 | if binary.left.awaits_context_type \/ binary.right.awaits_context_type then | |
| 320 | _deferred_operands.add(DEFERRED_OPERANDS(binary)) | |
| 321 | ||
| 322 | RETRY_SITE_STATS.note("operators.pre_binary_deferred") | |
| 323 | _logger.speculate() | |
| 324 | _flow.speculate() | |
| 325 | fi | |
| 326 | ||
| 327 | return false | |
| 328 | si | |
| 329 | ||
| 330 | // The operand walks of a binary carrying a context-typed | |
| 331 | // operand run inside a speculation opened by pre_binary; close | |
| 332 | // it here, whichever way the resolution below went. | |
| 333 | visit_binary(binary: Trees.Expressions.BINARY) is | |
| 334 | if !_deferred_for(binary)? then | |
| 335 | _visit_binary(binary) | |
| 336 | ||
| 337 | return | |
| 338 | fi | |
| 339 | ||
| 340 | try | |
| 341 | _visit_binary(binary) | |
| 342 | finally | |
| 343 | _deferred_operands.remove_at(_deferred_operands.count - 1) | |
| 344 | ||
| 345 | _flow.commit() | |
| 346 | _logger.commit() | |
| 347 | yrt | |
| 348 | si | |
| 349 | ||
| 350 | // The innermost binary currently deferring an operand, when it | |
| 351 | // is this one. Nested binaries push in walk order, so only the | |
| 352 | // top of the stack can be the node being visited. | |
| 353 | _deferred_for(node: Trees.Node) -> DEFERRED_OPERANDS? is | |
| 354 | if _deferred_operands.count == 0 then | |
| 355 | return null | |
| 356 | fi | |
| 357 | ||
| 358 | let top = _deferred_operands[_deferred_operands.count - 1] | |
| 359 | ||
| 360 | return if top.node == node then top else null fi | |
| 361 | si | |
| 362 | ||
| 363 | // Once resolution has settled on a single `function`, push its | |
| 364 | // formal type into an operand that was still waiting for one | |
| 365 | // and walk that operand again — the same step visit_call takes | |
| 366 | // for a waiting argument, and for the same reason: nothing | |
| 367 | // could type the operand until the callee was known. Resolution | |
| 368 | // reaches a function at all because an untyped operand carries | |
| 369 | // the ERROR type, which matches any formal, so the operator's | |
| 370 | // own declaration decides the target type rather than anything | |
| 371 | // being assumed about how operators are declared. | |
| 372 | // | |
| 373 | // True when an operand was re-walked, which invalidates every | |
| 374 | // type resolution just read off the operands; the caller starts | |
| 375 | // over against the settled ones. `retried` keeps that to a | |
| 376 | // single attempt, so an operand left error-typed by its second | |
| 377 | // walk does not drive another. | |
| 378 | _resolve_deferred_operands( | |
| 379 | binary: Trees.Expressions.BINARY, | |
| 380 | function: Semantic.Symbols.Function | |
| 381 | ) -> bool is | |
| 382 | let deferred = _deferred_for(binary) | |
| 383 | ||
| 384 | if !deferred? \/ deferred.retried then | |
| 385 | return false | |
| 386 | fi | |
| 387 | ||
| 388 | // An instance operator takes the left operand as its | |
| 389 | // receiver, so only the right is one of its arguments. A | |
| 390 | // waiting left operand cannot reach that path at all: its | |
| 391 | // ERROR type has no members, so no operator is found on it. | |
| 392 | let left_formal = | |
| 393 | if function.is_instance then null else _formal_type(function, 0) fi | |
| 394 | ||
| 395 | let right_formal = | |
| 396 | _formal_type(function, if function.is_instance then 0 else 1 fi) | |
| 397 | ||
| 398 | let left_type = if binary.left.awaits_context_type then left_formal else null fi | |
| 399 | let right_type = if binary.right.awaits_context_type then right_formal else null fi | |
| 400 | ||
| 401 | if !left_type? /\ !right_type? then | |
| 402 | return false | |
| 403 | fi | |
| 404 | ||
| 405 | deferred.retried = true | |
| 406 | ||
| 407 | let use retry_site = RETRY_SITE_STATS.enter("operators.resolve_deferred_operands", RetrySiteKind.REWALK_WITH_INFORMATION) | |
| 408 | _logger.roll_back() | |
| 409 | _logger.speculate() | |
| 410 | _flow.restore() | |
| 411 | ||
| 412 | if left_type? then | |
| 413 | binary.left.set_expected_type(left_type, "") | |
| 414 | fi | |
| 415 | ||
| 416 | if right_type? then | |
| 417 | binary.right.set_expected_type(right_type, "") | |
| 418 | fi | |
| 419 | ||
| 420 | _visitor.rewalk(binary.left) | |
| 421 | _visitor.rewalk(binary.right) | |
| 422 | ||
| 423 | return true | |
| 424 | si | |
| 425 | ||
| 426 | // An index by a `System.Range` that reached no indexer takes a | |
| 427 | // slice of the source instead. Only where no indexer matched, so | |
| 428 | // a type declaring its own `[System.Range]` indexer still wins, and | |
| 429 | // only for a read: there is no slice to assign through. | |
| 430 | _try_range_slice( | |
| 431 | index: Trees.Expressions.INDEX, | |
| 432 | source: Value, | |
| 433 | range: Value, | |
| 434 | index_type: Semantic.Types.Type | |
| 435 | ) -> bool is | |
| 436 | let resolved = _range_slice_resolver.try_resolve(index.location, source, index_type) | |
| 437 | ||
| 438 | if !resolved? then | |
| 439 | return false | |
| 440 | fi | |
| 441 | ||
| 442 | _symbol_use_locations.add_symbol_use(index.location, resolved.function) | |
| 443 | ||
| 444 | index.compile_expressions_state.value = | |
| 445 | _range_slice_resolver.call(index.location, resolved, source, range) | |
| 446 | ||
| 447 | return true | |
| 448 | si | |
| 449 | ||
| 450 | // The index counterpart of _resolve_deferred_operands: the | |
| 451 | // resolved indexer's first formal is the index argument's type. | |
| 452 | // Both accessors take the index there, so `get_Item` and | |
| 453 | // `set_Item` need no distinguishing. | |
| 454 | _resolve_deferred_index( | |
| 455 | index: Trees.Expressions.INDEX, | |
| 456 | function: Semantic.Symbols.Function | |
| 457 | ) -> bool is | |
| 458 | let deferred = _deferred_for(index) | |
| 459 | ||
| 460 | if !deferred? \/ deferred.retried then | |
| 461 | return false | |
| 462 | fi | |
| 463 | ||
| 464 | let formal = _formal_type(function, 0) | |
| 465 | ||
| 466 | if !formal? \/ !index.index.awaits_context_type then | |
| 467 | return false | |
| 468 | fi | |
| 469 | ||
| 470 | deferred.retried = true | |
| 471 | ||
| 472 | let use retry_site = RETRY_SITE_STATS.enter("operators.resolve_deferred_index", RetrySiteKind.REWALK_WITH_INFORMATION) | |
| 473 | _logger.roll_back() | |
| 474 | _logger.speculate() | |
| 475 | _flow.restore() | |
| 476 | ||
| 477 | index.index.set_expected_type(formal, "") | |
| 478 | _visitor.rewalk(index.index) | |
| 479 | ||
| 480 | return true | |
| 481 | si | |
| 482 | ||
| 483 | // The formal at `index`, or null when the function has no such | |
| 484 | // argument or the one it has is wild — a type variable free | |
| 485 | // only in the waiting operand's own slot pins nothing, and the | |
| 486 | // operand is left to report that it still has no type. | |
| 487 | _formal_type(function: Semantic.Symbols.Function, index: int) -> Type? is | |
| 488 | if index >= function.arguments.count then | |
| 489 | return null | |
| 490 | fi | |
| 491 | ||
| 492 | let formal = function.arguments[index] | |
| 493 | ||
| 494 | return if formal.is_wild then null else formal fi | |
| 495 | si | |
| 496 | ||
| 497 | _visit_binary(binary: Trees.Expressions.BINARY) is | |
| 498 | binary.compile_expressions_state.value = null | |
| 499 | ||
| 500 | // An operand with no type - a reference to a local variable | |
| 501 | // that is not defined yet, whose type is never inferred - has | |
| 502 | // nothing for overload resolution to match against, and every | |
| 503 | // consumer below reads the type as though it were there. | |
| 504 | if | |
| 505 | !binary.left.value? \/ !binary.right.value? \/ | |
| 506 | !binary.left.value.type? \/ !binary.right.value.type? | |
| 507 | then | |
| 508 | binary.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), binary.location) | |
| 509 | return | |
| 510 | fi | |
| 511 | ||
| 512 | // `??` does not go through overload resolution: the | |
| 513 | // "chain closer" vs "stays optional" distinction is | |
| 514 | // determined by the right operand's own nullability, | |
| 515 | // which a single typing rule expresses directly. Going | |
| 516 | // through the user-operator path would force this | |
| 517 | // distinction into two ambiguous prelude overloads. | |
| 518 | if binary.operation.name =~ "??" then | |
| 519 | _visit_null_coalesce(binary) | |
| 520 | return | |
| 521 | fi | |
| 522 | ||
| 523 | let left_value = binary.left.value | |
| 524 | let right_value = binary.right.value | |
| 525 | let left_is_consumable = left_value.check_is_consumable(_logger, binary.left.location) | |
| 526 | let right_is_consumable = right_value.check_is_consumable(_logger, binary.right.location) | |
| 527 | ||
| 528 | // Neither operand settled: an operand whose type is a | |
| 529 | // placeholder offers no candidates of its own, so with | |
| 530 | // both of them waiting nothing says which candidate is | |
| 531 | // meant, and resolving anyway pushes the formal of | |
| 532 | // whichever one was found onto both placeholders as a | |
| 533 | // bound. One settled operand is a different case - it is | |
| 534 | // what picks the candidate, and the candidate is then | |
| 535 | // entitled to say what the other operand must be - so | |
| 536 | // this waits only for the pair. | |
| 537 | if | |
| 538 | (left_value.type?.is_inferred ?? false) /\ | |
| 539 | (right_value.type?.is_inferred ?? false) /\ | |
| 540 | _defer_on_unsettled_operand( | |
| 541 | binary, | |
| 542 | binary.operation.location, | |
| 543 | left_value.type, | |
| 544 | right_value.type | |
| 545 | ) | |
| 546 | then | |
| 547 | return | |
| 548 | fi | |
| 549 | ||
| 550 | // `=~` over an optional operand gets its null checks | |
| 551 | // written around the call. This runs ahead of resolution | |
| 552 | // rather than as a fallback: only an optional *argument* | |
| 553 | // fails to resolve, while an optional *receiver* resolves | |
| 554 | // to an ordinary member call and dereferences null. | |
| 555 | let null_safe = _try_null_safe_equality(binary, left_value, right_value) | |
| 556 | ||
| 557 | if null_safe? then | |
| 558 | binary.compile_expressions_state.value = null_safe | |
| 559 | return | |
| 560 | fi | |
| 561 | ||
| 562 | // Two separate value/type/expression lists. The free-function | |
| 563 | // path takes both operands as arguments; the member-call path | |
| 564 | // takes only the right operand (left is the receiver). The | |
| 565 | // retry helper updates the lists in place when it re-walks, | |
| 566 | // so the two paths can't share storage. | |
| 567 | let binary_argument_values = Collections.LIST[Value]([left_value, right_value]) | |
| 568 | let binary_argument_types = Collections.LIST[Type]([left_value.type!, right_value.type!]) | |
| 569 | let binary_argument_expressions = Collections.LIST[Trees.Expressions.Expression]([binary.left, binary.right]) | |
| 570 | ||
| 571 | let member_argument_values = Collections.LIST[Value]([right_value]) | |
| 572 | let member_argument_types = Collections.LIST[Type]([right_value.type!]) | |
| 573 | let member_argument_expressions = Collections.LIST[Trees.Expressions.Expression]([binary.right]) | |
| 574 | ||
| 575 | let binary_function_group: Semantic.Symbols.FUNCTION_GROUP mut | |
| 576 | let binary_overload_result: Semantic.OVERLOAD_RESOLVE_RESULT? mut = null | |
| 577 | let binary_errors: Logging.DIAGNOSTICS_STATE? mut = null | |
| 578 | ||
| 579 | let binary_candidates = | |
| 580 | _static_operator_candidates( | |
| 581 | binary.operation.location, | |
| 582 | binary.operation.name, | |
| 583 | binary_argument_types | |
| 584 | ) | |
| 585 | ||
| 586 | if binary_candidates? then | |
| 587 | binary_function_group = binary_candidates | |
| 588 | ||
| 589 | (binary_overload_result, binary_errors) = | |
| 590 | _resolve_with_retry( | |
| 591 | binary.location, | |
| 592 | binary_function_group, | |
| 593 | binary_argument_values, | |
| 594 | binary_argument_types, | |
| 595 | binary_argument_expressions, | |
| 596 | _symbol_table.current_instance_context?, | |
| 597 | binary | |
| 598 | ) | |
| 599 | fi | |
| 600 | ||
| 601 | let member_overload_result: Semantic.OVERLOAD_RESOLVE_RESULT? mut = null | |
| 602 | let member_function_group: Semantic.Symbols.FUNCTION_GROUP mut | |
| 603 | let member_errors: Logging.DIAGNOSTICS_STATE? mut = null | |
| 604 | ||
| 605 | // An instance operator's left operand is `self`, which is | |
| 606 | // never absent, so no member candidate can accept a left | |
| 607 | // operand that may hold no value - the same rejection any | |
| 608 | // other non-optional formal makes of an optional actual. An | |
| 609 | // author who wants to answer for an absent left operand | |
| 610 | // declares a global operator taking `T?`, where the operand | |
| 611 | // really is an argument. `=~` and `!~` never reach here over | |
| 612 | // an optional operand: the null-safe path above answers them. | |
| 613 | // | |
| 614 | // The candidate is resolved against the arguments before it | |
| 615 | // is declined, so this is set only where the absent receiver | |
| 616 | // is the sole reason it did not apply. A candidate the | |
| 617 | // arguments would have rejected anyway keeps its own | |
| 618 | // diagnostic, which says what is actually wrong. | |
| 619 | let declined_absent_receiver mut = false | |
| 620 | ||
| 621 | if let binary.left.value?, value.type? then | |
| 622 | let member_candidates = | |
| 623 | _instance_operator_candidates( | |
| 624 | binary.operation.location, | |
| 625 | binary.operation.name, | |
| 626 | type.find_member(binary.operation.name) | |
| 627 | ) | |
| 628 | ||
| 629 | if member_candidates? then | |
| 630 | member_function_group = member_candidates | |
| 631 | ||
| 632 | (member_overload_result, member_errors) = | |
| 633 | _resolve_with_retry( | |
| 634 | binary.location, | |
| 635 | cast Semantic.Symbols.FUNCTION_GROUP(member_function_group), | |
| 636 | member_argument_values, | |
| 637 | member_argument_types, | |
| 638 | member_argument_expressions, | |
| 639 | value.is_consumable, | |
| 640 | binary | |
| 641 | ) | |
| 642 | ||
| 643 | // Discard a hidden member whether resolution | |
| 644 | // succeeded or failed. Keeping the diagnostics of a | |
| 645 | // failed one would report a candidate operator | |
| 646 | // resolution can never select, ahead of the real | |
| 647 | // error from the innate. | |
| 648 | if | |
| 649 | HIDDEN_OPERATOR_MEMBERS.is_hidden(member_function_group) \/ | |
| 650 | (member_overload_result? /\ member_overload_result.function.is_hidden_from_operator_resolution) | |
| 651 | then | |
| 652 | member_overload_result = null | |
| 653 | member_errors = null | |
| 654 | fi | |
| 655 | ||
| 656 | if member_overload_result? /\ _visitor.receiver_may_be_absent(binary.left) then | |
| 657 | declined_absent_receiver = true | |
| 658 | ||
| 659 | member_overload_result = null | |
| 660 | member_errors = null | |
| 661 | fi | |
| 662 | fi | |
| 663 | fi | |
| 664 | ||
| 665 | let function: Semantic.Symbols.Function? mut = null | |
| 666 | ||
| 667 | if member_overload_result? /\ binary_overload_result? then | |
| 668 | if cast int(member_overload_result.score) <= cast int(binary_overload_result.score) then | |
| 669 | function = member_overload_result.function | |
| 670 | else | |
| 671 | function = binary_overload_result.function | |
| 672 | fi | |
| 673 | elif member_overload_result? then | |
| 674 | function = member_overload_result.function | |
| 675 | elif binary_overload_result? then | |
| 676 | function = binary_overload_result.function | |
| 677 | fi | |
| 678 | ||
| 679 | if function? then | |
| 680 | // An operand that was waiting for a type now has the | |
| 681 | // resolved formal to take one from. Everything read off | |
| 682 | // the operands above is stale once it has been walked | |
| 683 | // again, so resolve the whole operator afresh. | |
| 684 | if _resolve_deferred_operands(binary, function) then | |
| 685 | _visit_binary(binary) | |
| 686 | ||
| 687 | return | |
| 688 | fi | |
| 689 | ||
| 690 | _symbol_use_locations.add_symbol_use(binary.operation.location, function) | |
| 691 | ||
| 692 | // Mirror the inferred-T constraint check in compile_calls: an | |
| 693 | // operator function resolved via overload resolution has its | |
| 694 | // type arguments bound by inference (the operator is never | |
| 695 | // explicitly specialized), so the declared kind / type-bound | |
| 696 | // constraints have not been checked yet. | |
| 697 | if | |
| 698 | function.is_generic /\ | |
| 699 | function.generic_arguments.count == function.generic_argument_names.count | |
| 700 | then | |
| 701 | Semantic.Symbols.GENERIC_CONSTRAINT_CHECKER().check_arguments( | |
| 702 | binary.location, | |
| 703 | _logger, | |
| 704 | function, | |
| 705 | function.generic_argument_names, | |
| 706 | function.generic_arguments | |
| 707 | ) | |
| 708 | fi | |
| 709 | ||
| 710 | let is_relational_rewrite = | |
| 711 | RELATIONAL_REWRITE.is_relational_rewrite(binary.operation.name, binary.actual_operation) | |
| 712 | ||
| 713 | let force_type: Type? mut = _ | |
| 714 | let want_not mut = false | |
| 715 | ||
| 716 | // A property of the operator's declaration, so it holds | |
| 717 | // however the call was spelled - the relational tokens | |
| 718 | // all rewrite to `<>`, and a directly written `<>` is | |
| 719 | // the same member with the same requirement. | |
| 720 | if | |
| 721 | binary.operation.name =~ "<>" /\ | |
| 722 | !function.return_type!.matches(_innate_symbol_lookup.get_int_type()) | |
| 723 | then | |
| 724 | // FIXME: do this check on the definition: | |
| 725 | _logger.error(binary.location, "<> order operator must return int") | |
| 726 | fi | |
| 727 | ||
| 728 | if is_relational_rewrite then | |
| 729 | force_type = _innate_symbol_lookup.get_bool_type() | |
| 730 | elif binary.operation.name =~ "==" then | |
| 731 | let left_type = binary.left.value?.type | |
| 732 | let right_type = binary.right.value?.type | |
| 733 | ||
| 734 | if | |
| 735 | left_is_consumable /\ right_is_consumable /\ | |
| 736 | left_type? /\ right_type? /\ | |
| 737 | cast int(left_type.compare(right_type)) > cast int(Semantic.Types.MATCH.ASSIGNABLE) /\ | |
| 738 | cast int(right_type.compare(left_type)) > cast int(Semantic.Types.MATCH.ASSIGNABLE) | |
| 739 | then | |
| 740 | if binary.actual_operation =~ "==" then | |
| 741 | _logger.error(binary.location, "== cannot be applied to values of non-assignable types") | |
| 742 | else | |
| 743 | _logger.error(binary.location, "!= cannot be applied to values of non-assignable types") | |
| 744 | fi | |
| 745 | elif | |
| 746 | isa Semantic.Symbols.InnateFunction(function) /\ | |
| 747 | function.innate_name =~ "compare.value" /\ | |
| 748 | left_type? /\ | |
| 749 | !VALUE_EQUALITY_OPERANDS.can_compare(left_type) | |
| 750 | then | |
| 751 | // compare.value lowers to a bare ceq, which for | |
| 752 | // struct operands the runtime either refuses at | |
| 753 | // JIT time or runs as a shallow bitwise | |
| 754 | // comparison rather than value equality. | |
| 755 | // Rejected here, where the operand type is known | |
| 756 | // and the location is useful. | |
| 757 | if binary.actual_operation =~ "==" then | |
| 758 | _logger.error(binary.location, "== cannot be applied to values of type {left_type}", binary.location, "help: use =~ to compare by value") | |
| 759 | else | |
| 760 | _logger.error(binary.location, "!= cannot be applied to values of type {left_type}", binary.location, "help: use !~ to compare by value") | |
| 761 | fi | |
| 762 | fi | |
| 763 | elif !function.is_innate /\ binary.actual_operation =~ "!~" then | |
| 764 | want_not = true | |
| 765 | fi | |
| 766 | ||
| 767 | let value: Value mut | |
| 768 | ||
| 769 | if function.is_unsafe_constraints then | |
| 770 | _logger.warn(binary.location, "unchecked-constraints", "call to {function} has unchecked constraints") | |
| 771 | fi | |
| 772 | ||
| 773 | // Pass the path-specific argument-value list so the | |
| 774 | // values used for the call reflect the retry's re-walks | |
| 775 | // for whichever group was selected — without this, a | |
| 776 | // member-path retry that re-walked the right operand | |
| 777 | // would overwrite values the binary-path retry already | |
| 778 | // committed to its own list (and vice versa). | |
| 779 | if function.is_instance then | |
| 780 | value = function.call(binary.location, left_value, member_argument_values, force_type, _function_caller) | |
| 781 | else | |
| 782 | // A pack-marked declared return type re-presents the | |
| 783 | // call's value as the N-ary function of the bound | |
| 784 | // tuple - the same presentation the named-call path | |
| 785 | // applies. Instance operators cannot carry the | |
| 786 | // marker: their left operand is a receiver, not an | |
| 787 | // argument the pack could spread. | |
| 788 | _calls.present_pack_arguments(binary, [binary.left, binary.right], function, binary_argument_values) | |
| 789 | ||
| 790 | _calls.feed_pack_from_expected(function, binary.expected_type) | |
| 791 | ||
| 792 | let wrapped = _calls.wrap_return_pack(binary, function, binary.location, null, binary_argument_values) | |
| 793 | ||
| 794 | if wrapped? then | |
| 795 | binary.compile_expressions_state.value = wrapped | |
| 796 | ||
| 797 | return | |
| 798 | fi | |
| 799 | ||
| 800 | value = function.call(binary.location, null, binary_argument_values, force_type, _function_caller) | |
| 801 | ||
| 802 | if isa Call.INNATE(value) then | |
| 803 | let innate_value = value | |
| 804 | ||
| 805 | innate_value.actual_operation = binary.actual_operation | |
| 806 | ||
| 807 | value = innate_value.lower() | |
| 808 | fi | |
| 809 | fi | |
| 810 | ||
| 811 | if !function.is_innate /\ is_relational_rewrite then | |
| 812 | value = COMPARE_ORDER_TO_ZERO(value, binary.actual_operation, _innate_symbol_lookup.get_bool_type()) | |
| 813 | fi | |
| 814 | ||
| 815 | if want_not then | |
| 816 | value = NOT(value) | |
| 817 | fi | |
| 818 | ||
| 819 | binary.compile_expressions_state.value = value | |
| 820 | else | |
| 821 | // `a =~ b` where no operator resolved but the operands | |
| 822 | // still compare: a bare type parameter or a tuple through | |
| 823 | // the runtime's comparer, two sequences element by | |
| 824 | // element, or a `<>` read against zero. | |
| 825 | let comparison = _try_lowered_equality(binary, left_value, right_value) | |
| 826 | ||
| 827 | if comparison? then | |
| 828 | let value = if binary.actual_operation =~ "!~" then NOT(comparison) else comparison fi | |
| 829 | ||
| 830 | binary.compile_expressions_state.value = value | |
| 831 | ||
| 832 | return | |
| 833 | fi | |
| 834 | ||
| 835 | // No operator can resolve against an operand whose type | |
| 836 | // is still an inference placeholder, and the walk that | |
| 837 | // settles it has not happened yet. Record an obligation | |
| 838 | // and leave the site for the next walk rather than | |
| 839 | // reporting an operator the user may well have: what the | |
| 840 | // message would name is `***`, and the type it is waiting | |
| 841 | // for arrives by ordinary inference. | |
| 842 | if | |
| 843 | _defer_on_unsettled_operand( | |
| 844 | binary, | |
| 845 | binary.operation.location, | |
| 846 | binary.left.value?.type, | |
| 847 | binary.right.value?.type | |
| 848 | ) | |
| 849 | then | |
| 850 | return | |
| 851 | fi | |
| 852 | ||
| 853 | // The type declares this operator but its left operand | |
| 854 | // may hold no value, so the member candidate was never | |
| 855 | // in the running. Reported here rather than left to the | |
| 856 | // global-path failure below, which would list the innate | |
| 857 | // overloads and never mention the operator the user | |
| 858 | // actually wrote. | |
| 859 | if declined_absent_receiver then | |
| 860 | let left_type = binary.left.value?.type | |
| 861 | let right_type = binary.right.value?.type | |
| 862 | ||
| 863 | // An error-typed operand already drew its own | |
| 864 | // diagnostic, and the member candidate only matched | |
| 865 | // because an error type is assignable to anything, so | |
| 866 | // reporting the operator here would render the error | |
| 867 | // type back at the user as if it were what they wrote. | |
| 868 | if | |
| 869 | !(left_type? /\ left_type.is_error) /\ | |
| 870 | !(right_type? /\ right_type.is_error) | |
| 871 | then | |
| 872 | _logger.error( | |
| 873 | binary.operation.location, | |
| 874 | "operator {left_type} {binary.operation} {right_type} not found", | |
| 875 | binary.operation.location, | |
| 876 | "help: an operator declared on a type takes a left operand that always holds a value; narrow the left operand first") | |
| 877 | fi | |
| 878 | ||
| 879 | binary.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), binary.location) | |
| 880 | ||
| 881 | return | |
| 882 | fi | |
| 883 | ||
| 884 | if binary_errors? /\ binary_errors.count > 0 then | |
| 885 | _logger.merge(binary_errors) | |
| 886 | fi | |
| 887 | ||
| 888 | if member_errors? /\ member_errors.count > 0 then | |
| 889 | _logger.merge(member_errors) | |
| 890 | fi | |
| 891 | ||
| 892 | // A compound-statement left operand got here through a | |
| 893 | // parenthesised group's expression reading; with no | |
| 894 | // operator resolving, the intended reading may have been | |
| 895 | // the block one, which needs a `;` after the statement. | |
| 896 | if isa Trees.Expressions.STATEMENT(binary.left) then | |
| 897 | _logger.info(binary.operation.location, "the compound statement reads as the left operand of this operator; end it with ; to read what follows as a separate statement") | |
| 898 | fi | |
| 899 | ||
| 900 | let left_type = binary.left.value?.type | |
| 901 | let right_type = binary.right.value?.type | |
| 902 | ||
| 903 | // An error-typed operand already drew its own diagnostic, | |
| 904 | // and no operator can resolve against it, so reporting the | |
| 905 | // operator as missing renders the error type back at the | |
| 906 | // user as if it were what they wrote. | |
| 907 | if | |
| 908 | (!binary_errors? \/ binary_errors.count == 0) /\ | |
| 909 | (!member_errors? \/ member_errors.count == 0) /\ | |
| 910 | !(left_type? /\ left_type.is_error) /\ | |
| 911 | !(right_type? /\ right_type.is_error) | |
| 912 | then | |
| 913 | _logger.error(binary.operation.location, "operator {left_type} {binary.operation} {right_type} not found") | |
| 914 | fi | |
| 915 | ||
| 916 | // FIXME QQ should probably do this | |
| 917 | binary.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), binary.location) | |
| 918 | fi | |
| 919 | si | |
| 920 | ||
| 921 | // No operator resolves against an operand whose type is still an | |
| 922 | // inference placeholder, and the walk that settles it has not | |
| 923 | // happened yet. Record an obligation and leave the site waiting | |
| 924 | // rather than reporting an operator the user may well have: the | |
| 925 | // message would name `***`, and the type it waits for arrives by | |
| 926 | // ordinary inference. The result waits with it, so a consumer | |
| 927 | // reads a placeholder rather than an ERROR that no later walk | |
| 928 | // displaces. | |
| 929 | _defer_on_unsettled_operand( | |
| 930 | node: Trees.Expressions.Expression, | |
| 931 | operator_location: Source.LOCATION, | |
| 932 | left_type: Semantic.Types.Type?, | |
| 933 | right_type: Semantic.Types.Type? | |
| 934 | ) -> bool is | |
| 935 | let unsettled = Semantic.OPERAND_WAIT.for_operands(left_type, right_type) | |
| 936 | ||
| 937 | if !unsettled? then | |
| 938 | return false | |
| 939 | fi | |
| 940 | ||
| 941 | Semantic.OBLIGATIONS.defer("operator", unsettled, operator_location) | |
| 942 | ||
| 943 | node.compile_expressions_state.value = | |
| 944 | DUMMY(Semantic.Types.INFERRED_JOIN_TYPE(unsettled), node.location) | |
| 945 | ||
| 946 | return true | |
| 947 | si | |
| 948 | ||
| 949 | // `a =~ b` where no operator resolved: the operands may still | |
| 950 | // compare through a lowering that is not an operator at all - | |
| 951 | // the runtime's comparer for a tuple or a bare type parameter, | |
| 952 | // element by element for two sequences, or a `<>` read against | |
| 953 | // zero. Identity is not offered here: two references of a class | |
| 954 | // declaring neither operator stay an error when written out, | |
| 955 | // and only compare by identity as a member of something that | |
| 956 | // synthesizes its own. Checked after resolution so a bound | |
| 957 | // declaring `=~` still resolves its own operator. | |
| 958 | _try_lowered_equality( | |
| 959 | binary: Trees.Expressions.BINARY, | |
| 960 | left_value: Value, | |
| 961 | right_value: Value | |
| 962 | ) -> Value? is | |
| 963 | if !(binary.operation.name =~ "=~") then | |
| 964 | return null | |
| 965 | fi | |
| 966 | ||
| 967 | let left_type = left_value.type | |
| 968 | let right_type = right_value.type | |
| 969 | ||
| 970 | if !left_type? \/ !right_type? then | |
| 971 | return null | |
| 972 | fi | |
| 973 | ||
| 974 | let lowering = _choose_equality(left_type, right_type, binary.location) | |
| 975 | ||
| 976 | if !lowering? \/ isa EqualityLowering.OPERATOR(lowering) \/ isa EqualityLowering.IDENTITY(lowering) then | |
| 977 | return null | |
| 978 | fi | |
| 979 | ||
| 980 | return _build_equality(lowering, left_value, right_value, binary.location) | |
| 981 | si | |
| 982 | ||
| 983 | ||
| 984 | // A reflected tuple type answers is_value_tuple; the | |
| 985 | // source-path type is Types.TUPLE directly. | |
| 986 | _is_tuple(type: Semantic.Types.Type) -> bool => | |
| 987 | type.is_value_tuple \/ isa Semantic.Types.TUPLE(type) | |
| 988 | ||
| 989 | // The types that cannot declare a `=~` of their own and so are | |
| 990 | // compared through the runtime's comparer instead. | |
| 991 | _compares_through_comparer(type: Semantic.Types.Type) -> bool => | |
| 992 | type.is_type_variable \/ _is_tuple(type) | |
| 993 | ||
| 994 | // Which comparison two present values of the given static types | |
| 995 | // get, decided once here for every place an equality is built. | |
| 996 | // | |
| 997 | // In order: an operator the left type declares or inherits, or | |
| 998 | // the innate or global one a scalar, string or enum carries; a | |
| 999 | // `<>` the type declares, read against zero; the runtime's | |
| 1000 | // comparer, for a tuple or a bare type parameter that can | |
| 1001 | // declare nothing; a sequence, element by element at the | |
| 1002 | // element's own static type; and reference identity for a class | |
| 1003 | // that declares neither operator. Null when nothing compares | |
| 1004 | // them - a struct declaring neither, or a sequence of one, where | |
| 1005 | // the bitwise or identity answer .NET would give is wrong rather | |
| 1006 | // than merely weak. | |
| 1007 | _choose_equality( | |
| 1008 | left_type: Type, | |
| 1009 | right_type: Type, | |
| 1010 | location: Source.LOCATION | |
| 1011 | ) -> EqualityLowering? => | |
| 1012 | _choose_equality(left_type, right_type, location, Collections.LIST[Type]()) | |
| 1013 | ||
| 1014 | // `resolving` holds the element types of the sequences being | |
| 1015 | // lowered further out. A type that is a sequence of itself - a | |
| 1016 | // class implementing `List` at itself, or two that implement | |
| 1017 | // `List` at each other - would otherwise be its own element | |
| 1018 | // for ever; the sequence rule declines for such an element and | |
| 1019 | // the class rules answer for it instead. | |
| 1020 | _choose_equality( | |
| 1021 | left_type: Type, | |
| 1022 | right_type: Type, | |
| 1023 | location: Source.LOCATION, | |
| 1024 | resolving: Collections.LIST[Type] | |
| 1025 | ) -> EqualityLowering? is | |
| 1026 | if left_type.is_error \/ right_type.is_error then | |
| 1027 | return null | |
| 1028 | fi | |
| 1029 | ||
| 1030 | let member = _find_member_equals_operator(left_type, right_type, location) | |
| 1031 | ||
| 1032 | if member? then | |
| 1033 | return EqualityLowering.OPERATOR(member) | |
| 1034 | fi | |
| 1035 | ||
| 1036 | let global_function = _find_global_equals_operator(left_type, right_type, location) | |
| 1037 | ||
| 1038 | if | |
| 1039 | global_function? /\ | |
| 1040 | NULL_SAFE_EQUALITY_GATE.accepts_global_operator( | |
| 1041 | global_function, | |
| 1042 | _innate_symbol_lookup.get_bool_type()) | |
| 1043 | then | |
| 1044 | return EqualityLowering.OPERATOR(global_function) | |
| 1045 | fi | |
| 1046 | ||
| 1047 | let order = _find_order_operator(left_type, right_type, location) | |
| 1048 | ||
| 1049 | if order? then | |
| 1050 | return EqualityLowering.ORDER(order) | |
| 1051 | fi | |
| 1052 | ||
| 1053 | if _compares_through_comparer(left_type) /\ left_type.matches(right_type) then | |
| 1054 | let comparer_type = _innate_symbol_lookup.get_equality_comparer_type(left_type) | |
| 1055 | ||
| 1056 | if comparer_type? then | |
| 1057 | return EqualityLowering.COMPARER(comparer_type) | |
| 1058 | fi | |
| 1059 | fi | |
| 1060 | ||
| 1061 | let left_element = _sequence_element_type(left_type) | |
| 1062 | let right_element = _sequence_element_type(right_type) | |
| 1063 | ||
| 1064 | if | |
| 1065 | left_element? /\ right_element? /\ | |
| 1066 | left_element.matches(right_element) /\ | |
| 1067 | !_is_resolving(left_element, resolving) | |
| 1068 | then | |
| 1069 | resolving.add(left_element) | |
| 1070 | ||
| 1071 | let element = _choose_equality(left_element, right_element, location, resolving) | |
| 1072 | ||
| 1073 | resolving.remove_at(resolving.count - 1) | |
| 1074 | ||
| 1075 | if element? then | |
| 1076 | return EqualityLowering.SEQUENCE(left_element, element) | |
| 1077 | fi | |
| 1078 | ||
| 1079 | return null | |
| 1080 | fi | |
| 1081 | ||
| 1082 | if | |
| 1083 | !isa Semantic.Types.NAMED(left_type) \/ | |
| 1084 | left_type.is_value_type \/ | |
| 1085 | !left_type.matches(right_type) | |
| 1086 | then | |
| 1087 | return null | |
| 1088 | fi | |
| 1089 | ||
| 1090 | // A class declaring neither operator. One declared in ghūl | |
| 1091 | // source with no `equals` of its own compares by reference, | |
| 1092 | // which is what the runtime comparer would answer for it | |
| 1093 | // too. Anything else keeps the comparer: an imported class | |
| 1094 | // overriding `Equals` without `IEquatable`, or a source | |
| 1095 | // class writing `equals` out, answers through that override | |
| 1096 | // and a bare reference test would not. | |
| 1097 | if | |
| 1098 | isa Semantic.Symbols.Classy(left_type.symbol) /\ | |
| 1099 | !left_type.symbol.is_reflected /\ | |
| 1100 | _equals_is_objects_own(left_type) | |
| 1101 | then | |
| 1102 | return EqualityLowering.IDENTITY | |
| 1103 | fi | |
| 1104 | ||
| 1105 | let comparer_type = _innate_symbol_lookup.get_equality_comparer_type(left_type) | |
| 1106 | ||
| 1107 | if comparer_type? then | |
| 1108 | return EqualityLowering.COMPARER(comparer_type) | |
| 1109 | fi | |
| 1110 | ||
| 1111 | return null | |
| 1112 | si | |
| 1113 | ||
| 1114 | // A `=~` the left type declares or inherits that takes the right | |
| 1115 | // type, reached with the left operand as its receiver. Hidden | |
| 1116 | // members - string's static op_Equality - are left to the global | |
| 1117 | // operator that stands in for them. | |
| 1118 | _find_member_equals_operator( | |
| 1119 | left_type: Type, | |
| 1120 | right_type: Type, | |
| 1121 | location: Source.LOCATION | |
| 1122 | ) -> Semantic.Symbols.Function? is | |
| 1123 | let member_symbol = left_type.find_member("=~") | |
| 1124 | ||
| 1125 | if !member_symbol? \/ !isa Semantic.Symbols.FUNCTION_GROUP(member_symbol) then | |
| 1126 | return null | |
| 1127 | fi | |
| 1128 | ||
| 1129 | let group = cast Semantic.Symbols.FUNCTION_GROUP(member_symbol) | |
| 1130 | ||
| 1131 | if HIDDEN_OPERATOR_MEMBERS.is_hidden(group) then | |
| 1132 | return null | |
| 1133 | fi | |
| 1134 | ||
| 1135 | let overload_result = | |
| 1136 | _resolve_silently(location, group, Collections.LIST[Type]([right_type]), true) | |
| 1137 | ||
| 1138 | if !overload_result? then | |
| 1139 | return null | |
| 1140 | fi | |
| 1141 | ||
| 1142 | let function = overload_result.function | |
| 1143 | ||
| 1144 | if | |
| 1145 | !NULL_SAFE_EQUALITY_GATE.accepts_operator( | |
| 1146 | function, | |
| 1147 | _innate_symbol_lookup.get_bool_type()) | |
| 1148 | then | |
| 1149 | return null | |
| 1150 | fi | |
| 1151 | ||
| 1152 | return function | |
| 1153 | si | |
| 1154 | ||
| 1155 | // A `<>` the left type declares or inherits that takes the right | |
| 1156 | // type and answers int, so it can be read against zero. | |
| 1157 | _find_order_operator( | |
| 1158 | left_type: Type, | |
| 1159 | right_type: Type, | |
| 1160 | location: Source.LOCATION | |
| 1161 | ) -> Semantic.Symbols.Function? is | |
| 1162 | let member_symbol = left_type.find_member("<>") | |
| 1163 | ||
| 1164 | if !member_symbol? \/ !isa Semantic.Symbols.FUNCTION_GROUP(member_symbol) then | |
| 1165 | return null | |
| 1166 | fi | |
| 1167 | ||
| 1168 | let group = cast Semantic.Symbols.FUNCTION_GROUP(member_symbol) | |
| 1169 | ||
| 1170 | if HIDDEN_OPERATOR_MEMBERS.is_hidden(group) then | |
| 1171 | return null | |
| 1172 | fi | |
| 1173 | ||
| 1174 | let overload_result = | |
| 1175 | _resolve_silently(location, group, Collections.LIST[Type]([right_type]), true) | |
| 1176 | ||
| 1177 | if !overload_result? then | |
| 1178 | return null | |
| 1179 | fi | |
| 1180 | ||
| 1181 | let function = overload_result.function | |
| 1182 | ||
| 1183 | if | |
| 1184 | !(function.is_instance \/ isa Semantic.Symbols.INNATE_METHOD(function)) \/ | |
| 1185 | function.is_hidden_from_operator_resolution \/ | |
| 1186 | function.arguments.count != 1 | |
| 1187 | then | |
| 1188 | return null | |
| 1189 | fi | |
| 1190 | ||
| 1191 | let return_type = function.return_type | |
| 1192 | ||
| 1193 | if !return_type? \/ !return_type.matches(_innate_symbol_lookup.get_int_type()) then | |
| 1194 | return null | |
| 1195 | fi | |
| 1196 | ||
| 1197 | return function | |
| 1198 | si | |
| 1199 | ||
| 1200 | _is_resolving(type: Type, resolving: Collections.LIST[Type]) -> bool is | |
| 1201 | for t in resolving do | |
| 1202 | if t.matches(type) then | |
| 1203 | return true | |
| 1204 | fi | |
| 1205 | od | |
| 1206 | ||
| 1207 | return false | |
| 1208 | si | |
| 1209 | ||
| 1210 | // Whether the only `equals` a type has is the one every object | |
| 1211 | // inherits: nothing along its ancestry overrides it, so a | |
| 1212 | // reference test and the runtime comparer answer alike. | |
| 1213 | _equals_is_objects_own(type: Type) -> bool is | |
| 1214 | let member = type.find_member("equals") | |
| 1215 | ||
| 1216 | if !member? then | |
| 1217 | return true | |
| 1218 | fi | |
| 1219 | ||
| 1220 | if !isa Semantic.Symbols.FUNCTION_GROUP(member) then | |
| 1221 | return false | |
| 1222 | fi | |
| 1223 | ||
| 1224 | let object_symbol = _innate_symbol_lookup.get_object_type().symbol.unspecialized_symbol | |
| 1225 | ||
| 1226 | for function in cast Semantic.Symbols.FUNCTION_GROUP(member).functions do | |
| 1227 | let owner = function.owner | |
| 1228 | ||
| 1229 | if !owner? \/ owner.unspecialized_symbol != object_symbol then | |
| 1230 | return false | |
| 1231 | fi | |
| 1232 | od | |
| 1233 | ||
| 1234 | return true | |
| 1235 | si | |
| 1236 | ||
| 1237 | // The element type of an array or list, and null for anything | |
| 1238 | // that is neither. A string is not one: it satisfies neither | |
| 1239 | // `List[char]` nor an array, and it has its own operator anyway. | |
| 1240 | _sequence_element_type(type: Type) -> Type? is | |
| 1241 | if let array: Semantic.Types.ARRAY = type then | |
| 1242 | return array.arguments[0] | |
| 1243 | fi | |
| 1244 | ||
| 1245 | let list = _innate_symbol_lookup.get_unspecialized_list_type() | |
| 1246 | ||
| 1247 | return Semantic.Symbols.TYPE_ARGUMENT_EXTRACTOR.extract(type, list) | |
| 1248 | si | |
| 1249 | ||
| 1250 | // The comparison a lowering describes, over two present values. | |
| 1251 | _build_equality( | |
| 1252 | lowering: EqualityLowering, | |
| 1253 | left_value: Value, | |
| 1254 | right_value: Value, | |
| 1255 | location: Source.LOCATION | |
| 1256 | ) -> Value is | |
| 1257 | let bool_type = _innate_symbol_lookup.get_bool_type() | |
| 1258 | ||
| 1259 | case lowering | |
| 1260 | when operator: EqualityLowering.OPERATOR then | |
| 1261 | return _build_operator_call(operator.function, "=~", left_value, right_value, location) | |
| 1262 | when order: EqualityLowering.ORDER then | |
| 1263 | let call = _build_operator_call(order.function, "<>", left_value, right_value, location) | |
| 1264 | ||
| 1265 | return COMPARE_ORDER_TO_ZERO(call, "==", bool_type) | |
| 1266 | when comparer: EqualityLowering.COMPARER then | |
| 1267 | return EQUALITY_COMPARISON(left_value, right_value, comparer.comparer_type, bool_type) | |
| 1268 | when sequence: EqualityLowering.SEQUENCE then | |
| 1269 | return _build_sequence_equality(sequence, left_value, right_value, location) | |
| 1270 | else | |
| 1271 | return REFERENCE_EQUALITY(left_value, right_value, bool_type) | |
| 1272 | esac | |
| 1273 | si | |
| 1274 | ||
| 1275 | // A call of an operator over two present operands. A declared | |
| 1276 | // operator takes the left operand as its receiver; an innate or | |
| 1277 | // a global one takes both as arguments. An innate lowers to an | |
| 1278 | // opcode and has to be told which spelling it stands in for - | |
| 1279 | // the positive one always, since `!~` negates the whole result. | |
| 1280 | _build_operator_call( | |
| 1281 | function: Semantic.Symbols.Function, | |
| 1282 | spelling: string, | |
| 1283 | left_value: Value, | |
| 1284 | right_value: Value, | |
| 1285 | location: Source.LOCATION | |
| 1286 | ) -> Value is | |
| 1287 | _symbol_use_locations.add_symbol_use(location, function) | |
| 1288 | ||
| 1289 | let value = | |
| 1290 | if function.is_instance then | |
| 1291 | function.call( | |
| 1292 | location, | |
| 1293 | left_value, | |
| 1294 | Collections.LIST[Value]([right_value]), | |
| 1295 | null, | |
| 1296 | _function_caller | |
| 1297 | ) | |
| 1298 | else | |
| 1299 | function.call( | |
| 1300 | location, | |
| 1301 | null, | |
| 1302 | Collections.LIST[Value]([left_value, right_value]), | |
| 1303 | null, | |
| 1304 | _function_caller | |
| 1305 | ) | |
| 1306 | fi | |
| 1307 | ||
| 1308 | if isa Call.INNATE(value) then | |
| 1309 | let innate_value = value | |
| 1310 | ||
| 1311 | innate_value.actual_operation = spelling | |
| 1312 | ||
| 1313 | return innate_value.lower() | |
| 1314 | fi | |
| 1315 | ||
| 1316 | return value | |
| 1317 | si | |
| 1318 | ||
| 1319 | // Two sequences compared by count and then element by element. | |
| 1320 | // Each operand is read once per element and its count twice, so | |
| 1321 | // both are spilled; the element comparison is built against a | |
| 1322 | // load of the index local the loop node declares, at the element | |
| 1323 | // lowering already chosen. | |
| 1324 | _build_sequence_equality( | |
| 1325 | sequence: EqualityLowering.SEQUENCE, | |
| 1326 | left_value: Value, | |
| 1327 | right_value: Value, | |
| 1328 | location: Source.LOCATION | |
| 1329 | ) -> Value is | |
| 1330 | let bool_type = _innate_symbol_lookup.get_bool_type() | |
| 1331 | let int_type = _innate_symbol_lookup.get_int_type() | |
| 1332 | ||
| 1333 | let block = IR.Values.BLOCK(bool_type) | |
| 1334 | ||
| 1335 | let load_left = left_value.get_temp_copier(block, "sequence_left") | |
| 1336 | let load_right = right_value.get_temp_copier(block, "sequence_right") | |
| 1337 | ||
| 1338 | let left_count = _load_property(load_left(), "count", location) | |
| 1339 | let right_count = _load_property(load_right(), "count", location) | |
| 1340 | ||
| 1341 | if !left_count? \/ !right_count? then | |
| 1342 | _logger.error(location, "cannot compare {left_value.type} element-wise: it has no count") | |
| 1343 | ||
| 1344 | return DUMMY(Semantic.Types.ERROR(), location) | |
| 1345 | fi | |
| 1346 | ||
| 1347 | let left_count_temp = IR.TEMP(block, "sequence_left_count", left_count) | |
| 1348 | let right_count_temp = IR.TEMP(block, "sequence_right_count", right_count) | |
| 1349 | ||
| 1350 | let index_name = ".sequence_index.{IR.TEMP.get_next_id()}" | |
| 1351 | ||
| 1352 | let left_element = _index_element(load_left(), IR.Values.Load.TEMP(index_name, int_type), location) | |
| 1353 | let right_element = _index_element(load_right(), IR.Values.Load.TEMP(index_name, int_type), location) | |
| 1354 | ||
| 1355 | if !left_element? \/ !right_element? then | |
| 1356 | _logger.error(location, "cannot compare {left_value.type} element-wise: it has no indexer") | |
| 1357 | ||
| 1358 | return DUMMY(Semantic.Types.ERROR(), location) | |
| 1359 | fi | |
| 1360 | ||
| 1361 | let element_equals = _build_equality(sequence.element, left_element, right_element, location) | |
| 1362 | ||
| 1363 | block.add( | |
| 1364 | SEQUENCE_EQUALITY( | |
| 1365 | left_count_temp.load(), | |
| 1366 | right_count_temp.load(), | |
| 1367 | index_name, | |
| 1368 | int_type, | |
| 1369 | element_equals, | |
| 1370 | bool_type)) | |
| 1371 | ||
| 1372 | block.close() | |
| 1373 | ||
| 1374 | return block | |
| 1375 | si | |
| 1376 | ||
| 1377 | // A read of a named property on a receiver, or null when the | |
| 1378 | // receiver's type has no property of that name. | |
| 1379 | _load_property(receiver: Value, name: string, location: Source.LOCATION) -> Value? is | |
| 1380 | let type = receiver.type | |
| 1381 | ||
| 1382 | if !type? then | |
| 1383 | return null | |
| 1384 | fi | |
| 1385 | ||
| 1386 | let symbol = type.find_member(name) | |
| 1387 | ||
| 1388 | if let property: Semantic.Symbols.Property = symbol then | |
| 1389 | return property.load(location, receiver, IoC.CONTAINER.instance.symbol_loader) | |
| 1390 | fi | |
| 1391 | ||
| 1392 | return null | |
| 1393 | si | |
| 1394 | ||
| 1395 | // `receiver[index]` through the receiver type's read indexer, or | |
| 1396 | // null when none takes the index. | |
| 1397 | _index_element(receiver: Value, index: Value, location: Source.LOCATION) -> Value? is | |
| 1398 | let type = receiver.type | |
| 1399 | ||
| 1400 | if !type? \/ !index.type? then | |
| 1401 | return null | |
| 1402 | fi | |
| 1403 | ||
| 1404 | let symbol = type.find_member(Semantic.Symbols.INDEXER_NAMES.read) | |
| 1405 | ||
| 1406 | if !symbol? \/ !isa Semantic.Symbols.FUNCTION_GROUP(symbol) then | |
| 1407 | return null | |
| 1408 | fi | |
| 1409 | ||
| 1410 | let overload_result = | |
| 1411 | _resolve_silently( | |
| 1412 | location, | |
| 1413 | cast Semantic.Symbols.FUNCTION_GROUP(symbol), | |
| 1414 | Collections.LIST[Type]([index.type!]), | |
| 1415 | true) | |
| 1416 | ||
| 1417 | if !overload_result? then | |
| 1418 | return null | |
| 1419 | fi | |
| 1420 | ||
| 1421 | let function = overload_result.function | |
| 1422 | ||
| 1423 | _symbol_use_locations.add_symbol_use(location, function) | |
| 1424 | ||
| 1425 | return function.call(location, receiver, Collections.LIST[Value]([index]), null, _function_caller) | |
| 1426 | si | |
| 1427 | ||
| 1428 | ||
| 1429 | // A field comparison in a synthesized union `=~`. The operands | |
| 1430 | // are plain member loads compiled by the ordinary walk; what is | |
| 1431 | // decided here is which comparison they run, which depends on | |
| 1432 | // the field's static type and so was not knowable when the body | |
| 1433 | // was built. | |
| 1434 | // The whole body of a synthesized `=~`, emitted here rather | |
| 1435 | // than built as a tree where the members were named. What the | |
| 1436 | // comparison does depends on the owner's kind, on what its | |
| 1437 | // ancestors contribute and on each member's static type, none | |
| 1438 | // of which exist where a body would have to be written. | |
| 1439 | // | |
| 1440 | // Three guards, one per kind of owner. A struct has no other | |
| 1441 | // runtime type to be confused with, so it needs none. A union | |
| 1442 | // variant tests `isa` against itself: its parameter is the | |
| 1443 | // union, and no other variant can pass. A class compares | |
| 1444 | // runtime types, because a subclass value passes an `isa` for | |
| 1445 | // its base and the two must not compare equal. | |
| 1446 | visit_memberwise_equals(memberwise: Trees.Expressions.MEMBERWISE_EQUALS) is | |
| 1447 | memberwise.compile_expressions_state.value = null | |
| 1448 | ||
| 1449 | let bool_type = _innate_symbol_lookup.get_bool_type() | |
| 1450 | let location = memberwise.location | |
| 1451 | ||
| 1452 | let owner = _visitor.current_instance_context | |
| 1453 | ||
| 1454 | if !owner? \/ !isa Semantic.Symbols.Classy(owner) then | |
| 1455 | memberwise.compile_expressions_state.value = | |
| 1456 | DUMMY(Semantic.Types.ERROR(), location) | |
| 1457 | ||
| 1458 | return | |
| 1459 | fi | |
| 1460 | ||
| 1461 | let owner_classy = cast Semantic.Symbols.Classy(owner) | |
| 1462 | ||
| 1463 | let self_value = _load_self(owner_classy, location) | |
| 1464 | let other_value = _load_other(location) | |
| 1465 | ||
| 1466 | if !self_value? \/ !other_value? then | |
| 1467 | memberwise.compile_expressions_state.value = | |
| 1468 | DUMMY(Semantic.Types.ERROR(), location) | |
| 1469 | ||
| 1470 | return | |
| 1471 | fi | |
| 1472 | ||
| 1473 | let inherited = _inherited_memberwise_equals(owner_classy) | |
| 1474 | ||
| 1475 | let operands = Collections.LIST[Value]() | |
| 1476 | ||
| 1477 | let guard = _memberwise_guard(owner_classy, self_value, other_value, location) | |
| 1478 | ||
| 1479 | if guard? then | |
| 1480 | operands.add(guard) | |
| 1481 | fi | |
| 1482 | ||
| 1483 | // Read through the owner's own type: a class parameter is | |
| 1484 | // the type the whole chain overrides at, which is a base | |
| 1485 | // of this one wherever this class is not the root. | |
| 1486 | let other_as_owner = _narrow_to_owner(other_value, owner_classy, location) | |
| 1487 | ||
| 1488 | for i in 0..memberwise.members.count do | |
| 1489 | let member = memberwise.members[i] | |
| 1490 | ||
| 1491 | // The member's own declaration, so that a report about | |
| 1492 | // how it compares lands where it was written. | |
| 1493 | let member_location = memberwise.member_locations[i] | |
| 1494 | ||
| 1495 | let left = _load_member(self_value, owner_classy, member, member_location) | |
| 1496 | let right = _load_member(other_as_owner, owner_classy, member, member_location) | |
| 1497 | ||
| 1498 | if !left? \/ !right? then | |
| 1499 | continue | |
| 1500 | fi | |
| 1501 | ||
| 1502 | operands.add( | |
| 1503 | _compile_field_equals( | |
| 1504 | left, | |
| 1505 | right, | |
| 1506 | member_location, | |
| 1507 | memberwise.reports_fallback | |
| 1508 | ) | |
| 1509 | ) | |
| 1510 | ||
| 1511 | _note_memberwise_callees( | |
| 1512 | memberwise.called_functions, | |
| 1513 | left.type, | |
| 1514 | right.type, | |
| 1515 | member_location | |
| 1516 | ) | |
| 1517 | od | |
| 1518 | ||
| 1519 | // Whatever the base holds is compared by the base's own | |
| 1520 | // operator, reached non-virtually so that it answers for | |
| 1521 | // its own members rather than dispatching back to this | |
| 1522 | // one. A base that compares nothing is not called at all: | |
| 1523 | // its operator is reference identity, which would answer | |
| 1524 | // false for two distinct values this class holds equal. | |
| 1525 | if inherited? then | |
| 1526 | memberwise.called_functions.add(inherited) | |
| 1527 | ||
| 1528 | operands.add( | |
| 1529 | IR.Values.Call.INSTANCE( | |
| 1530 | IR.Values.Load.SUPER(owner_classy), | |
| 1531 | inherited, | |
| 1532 | Collections.LIST[Value]([other_value]), | |
| 1533 | bool_type | |
| 1534 | ) | |
| 1535 | ) | |
| 1536 | fi | |
| 1537 | ||
| 1538 | memberwise.compile_expressions_state.value = ALL_OF(operands, bool_type) | |
| 1539 | si | |
| 1540 | ||
| 1541 | // `self`, at the owner's own type. A value type is loaded by | |
| 1542 | // address, as it is anywhere else it is read from. | |
| 1543 | _load_self(owner: Semantic.Symbols.Classy, location: Source.LOCATION) -> Value? is | |
| 1544 | let type = _own_instance_type(owner, location) | |
| 1545 | ||
| 1546 | if owner.is_value_type then | |
| 1547 | return IR.Values.Load.VALUE_SELF(owner, type) | |
| 1548 | fi | |
| 1549 | ||
| 1550 | return IR.Values.Load.REFERENCE_SELF(owner, type) | |
| 1551 | si | |
| 1552 | ||
| 1553 | // The type a value of the owner has inside its own body. A | |
| 1554 | // generic owner is its own instantiation at its own parameters, | |
| 1555 | // as reading `self` builds it: the unspecialized symbol's type | |
| 1556 | // would name the open form, and a field read through that is | |
| 1557 | // not a field of any type that exists. | |
| 1558 | _own_instance_type( | |
| 1559 | owner: Semantic.Symbols.Classy, | |
| 1560 | location: Source.LOCATION | |
| 1561 | ) -> Semantic.Types.Type? is | |
| 1562 | if owner.argument_names.count == 0 then | |
| 1563 | return owner.type | |
| 1564 | fi | |
| 1565 | ||
| 1566 | let arguments = Collections.LIST[Type]() | |
| 1567 | ||
| 1568 | for name in owner.argument_names do | |
| 1569 | let argument = owner.find_member(name) | |
| 1570 | let argument_type = if argument? then argument.type else null fi | |
| 1571 | ||
| 1572 | if argument? /\ argument.is_type_variable /\ argument_type? then | |
| 1573 | arguments.add(argument_type) | |
| 1574 | fi | |
| 1575 | od | |
| 1576 | ||
| 1577 | if arguments.count != owner.argument_names.count then | |
| 1578 | return owner.type | |
| 1579 | fi | |
| 1580 | ||
| 1581 | return Semantic.Types.GENERIC(location, owner, arguments) | |
| 1582 | si | |
| 1583 | ||
| 1584 | // The operator's own parameter, found by the name the | |
| 1585 | // synthesis gave it. | |
| 1586 | _load_other(location: Source.LOCATION) -> Value? is | |
| 1587 | let symbol = _visitor.try_find(Trees.Identifiers.Identifier(location, "other")) | |
| 1588 | ||
| 1589 | if !symbol? then | |
| 1590 | return null | |
| 1591 | fi | |
| 1592 | ||
| 1593 | return IR.Values.Load.LOCAL_ARGUMENT(symbol) | |
| 1594 | si | |
| 1595 | ||
| 1596 | // What the comparison tests before it reads a member. A struct | |
| 1597 | // has no other runtime type to be handed, so it needs nothing. | |
| 1598 | // A variant's parameter is its union, and testing `isa` against | |
| 1599 | // itself turns away every other variant. A class needs the | |
| 1600 | // runtime types to agree: a subclass value passes an `isa` for | |
| 1601 | // its base, and a base and a subclass must not compare equal. | |
| 1602 | _memberwise_guard( | |
| 1603 | owner: Semantic.Symbols.Classy, | |
| 1604 | self_value: Value, | |
| 1605 | other_value: Value, | |
| 1606 | location: Source.LOCATION | |
| 1607 | ) -> Value? is | |
| 1608 | let bool_type = _innate_symbol_lookup.get_bool_type() | |
| 1609 | ||
| 1610 | if owner.is_value_type then | |
| 1611 | return null | |
| 1612 | fi | |
| 1613 | ||
| 1614 | if owner.is_variant then | |
| 1615 | return IR.Values.ISA(bool_type, _own_instance_type(owner, location)!, other_value) | |
| 1616 | fi | |
| 1617 | ||
| 1618 | let self_type = _load_runtime_type(self_value, location) | |
| 1619 | let other_type = _load_runtime_type(other_value, location) | |
| 1620 | ||
| 1621 | if !self_type? \/ !other_type? then | |
| 1622 | return null | |
| 1623 | fi | |
| 1624 | ||
| 1625 | return REFERENCE_EQUALITY(self_type, other_type, bool_type) | |
| 1626 | si | |
| 1627 | ||
| 1628 | // `value.get_type()`, the runtime type of a value. | |
| 1629 | _load_runtime_type(value: Value, location: Source.LOCATION) -> Value? is | |
| 1630 | let object_type = _innate_symbol_lookup.get_object_type() | |
| 1631 | let group = object_type.find_member("get_type") | |
| 1632 | ||
| 1633 | if !group? \/ !isa Semantic.Symbols.FUNCTION_GROUP(group) then | |
| 1634 | return null | |
| 1635 | fi | |
| 1636 | ||
| 1637 | let functions = (cast Semantic.Symbols.FUNCTION_GROUP(group)).functions | |
| 1638 | ||
| 1639 | for function in functions do | |
| 1640 | if function.arguments.count == 0 then | |
| 1641 | return IR.Values.Call.INSTANCE( | |
| 1642 | value, | |
| 1643 | function, | |
| 1644 | Collections.LIST[Value](), | |
| 1645 | function.return_type | |
| 1646 | ) | |
| 1647 | fi | |
| 1648 | od | |
| 1649 | ||
| 1650 | return null | |
| 1651 | si | |
| 1652 | ||
| 1653 | // The parameter read as the owner. Where the owner is a class | |
| 1654 | // below the one the chain overrides at, or a variant of a | |
| 1655 | // union, the parameter is that wider type and the members | |
| 1656 | // declared here are reached through a cast the guard has | |
| 1657 | // already made safe. | |
| 1658 | _narrow_to_owner( | |
| 1659 | other_value: Value, | |
| 1660 | owner: Semantic.Symbols.Classy, | |
| 1661 | location: Source.LOCATION | |
| 1662 | ) -> Value is | |
| 1663 | let owner_type = _own_instance_type(owner, location) | |
| 1664 | ||
| 1665 | if !owner_type? then | |
| 1666 | return other_value | |
| 1667 | fi | |
| 1668 | ||
| 1669 | let value_type = other_value.type | |
| 1670 | ||
| 1671 | if value_type? /\ value_type.matches(owner_type) then | |
| 1672 | return other_value | |
| 1673 | fi | |
| 1674 | ||
| 1675 | // The guard has already established the runtime type, so | |
| 1676 | // the cast cannot fail where it is reached. | |
| 1677 | return IR.Values.CAST(owner_type, other_value, false) | |
| 1678 | si | |
| 1679 | ||
| 1680 | // One member, read off a value of the owner. The name is the | |
| 1681 | // one a value is read by rather than the one it was declared | |
| 1682 | // under, so an auto-property arrives here as its backing field. | |
| 1683 | _load_member( | |
| 1684 | receiver: Value, | |
| 1685 | owner: Semantic.Symbols.Classy, | |
| 1686 | name: string, | |
| 1687 | location: Source.LOCATION | |
| 1688 | ) -> Value? is | |
| 1689 | let symbol = owner.find_member(name) | |
| 1690 | ||
| 1691 | if !symbol? then | |
| 1692 | return null | |
| 1693 | fi | |
| 1694 | ||
| 1695 | if symbol.is_field then | |
| 1696 | return IR.Values.Load.INSTANCE_FIELD(receiver, symbol) | |
| 1697 | fi | |
| 1698 | ||
| 1699 | // A variant reads the fields it takes from its union's | |
| 1700 | // header through the union's own properties: the storage | |
| 1701 | // is the union's, and nothing on the variant names it. | |
| 1702 | if let property: Semantic.Symbols.Property = symbol then | |
| 1703 | return property.load(location, receiver, IoC.CONTAINER.instance.symbol_loader) | |
| 1704 | fi | |
| 1705 | ||
| 1706 | return null | |
| 1707 | si | |
| 1708 | ||
| 1709 | // The base's own operator, where calling it is what compares | |
| 1710 | // the members this class does not declare. Null when there is | |
| 1711 | // nothing to delegate: a struct or a variant has no base to | |
| 1712 | // ask, and a base whose chain holds no members compares by | |
| 1713 | // reference, which would answer false for two distinct values | |
| 1714 | // this class holds equal. | |
| 1715 | _inherited_memberwise_equals( | |
| 1716 | owner: Semantic.Symbols.Classy | |
| 1717 | ) -> Semantic.Symbols.Function? is | |
| 1718 | if owner.is_value_type \/ owner.is_variant then | |
| 1719 | return null | |
| 1720 | fi | |
| 1721 | ||
| 1722 | let base = _base_classy(owner) | |
| 1723 | ||
| 1724 | if !base? \/ !_holds_members(base, 0) then | |
| 1725 | return null | |
| 1726 | fi | |
| 1727 | ||
| 1728 | let group = base.find_member("=~") | |
| 1729 | ||
| 1730 | if !group? \/ !isa Semantic.Symbols.FUNCTION_GROUP(group) then | |
| 1731 | return null | |
| 1732 | fi | |
| 1733 | ||
| 1734 | for function in (cast Semantic.Symbols.FUNCTION_GROUP(group)).functions do | |
| 1735 | if function.arguments.count == 1 /\ !function.is_abstract then | |
| 1736 | return function | |
| 1737 | fi | |
| 1738 | od | |
| 1739 | ||
| 1740 | return null | |
| 1741 | si | |
| 1742 | ||
| 1743 | _base_classy(owner: Semantic.Symbols.Classy) -> Semantic.Symbols.Classy? is | |
| 1744 | for ancestor in owner.ancestors do | |
| 1745 | if !ancestor.is_class then | |
| 1746 | continue | |
| 1747 | fi | |
| 1748 | ||
| 1749 | let symbol = ancestor.symbol | |
| 1750 | ||
| 1751 | if isa Semantic.Symbols.Classy(symbol) then | |
| 1752 | return cast Semantic.Symbols.Classy(symbol) | |
| 1753 | fi | |
| 1754 | od | |
| 1755 | ||
| 1756 | return null | |
| 1757 | si | |
| 1758 | ||
| 1759 | // Whether a type, or anything it extends, holds state a | |
| 1760 | // comparison could read. | |
| 1761 | _holds_members(owner: Semantic.Symbols.Classy, depth: int) -> bool is | |
| 1762 | if depth > 64 then | |
| 1763 | return false | |
| 1764 | fi | |
| 1765 | ||
| 1766 | for member in owner.symbols do | |
| 1767 | if member.is_field /\ member.is_instance then | |
| 1768 | return true | |
| 1769 | fi | |
| 1770 | od | |
| 1771 | ||
| 1772 | let base = _base_classy(owner) | |
| 1773 | ||
| 1774 | return base? /\ _holds_members(base, depth + 1) | |
| 1775 | si | |
| 1776 | ||
| 1777 | // Every function a member's comparison can reach, taken from | |
| 1778 | // the same chooser that decides the comparison. A synthesized | |
| 1779 | // body stores nothing itself, so these are exactly what it can | |
| 1780 | // do, and the effects solve is handed them rather than left to | |
| 1781 | // read them back out of emitted values. | |
| 1782 | // | |
| 1783 | // Asking the chooser a second time costs a resolution and | |
| 1784 | // keeps the answer a total match over a closed union, which | |
| 1785 | // reading the built value back would not be: a value kind | |
| 1786 | // nobody thought of would contribute nothing and the body | |
| 1787 | // would look purer than it is. | |
| 1788 | _note_memberwise_callees( | |
| 1789 | into: Collections.LIST[Semantic.Symbols.Function], | |
| 1790 | left_type: Type?, | |
| 1791 | right_type: Type?, | |
| 1792 | location: Source.LOCATION | |
| 1793 | ) is | |
| 1794 | if !left_type? \/ !right_type? then | |
| 1795 | return | |
| 1796 | fi | |
| 1797 | ||
| 1798 | let left_inner = _non_optional(left_type) ?? left_type | |
| 1799 | let right_inner = _non_optional(right_type) ?? right_type | |
| 1800 | ||
| 1801 | let lowering = _choose_equality(left_inner, right_inner, location) | |
| 1802 | ||
| 1803 | if !lowering? then | |
| 1804 | return | |
| 1805 | fi | |
| 1806 | ||
| 1807 | _note_lowering_callees(into, lowering) | |
| 1808 | si | |
| 1809 | ||
| 1810 | _note_lowering_callees( | |
| 1811 | into: Collections.LIST[Semantic.Symbols.Function], | |
| 1812 | lowering: EqualityLowering | |
| 1813 | ) is | |
| 1814 | case lowering | |
| 1815 | when operator: EqualityLowering.OPERATOR then | |
| 1816 | into.add(operator.function) | |
| 1817 | when order: EqualityLowering.ORDER then | |
| 1818 | into.add(order.function) | |
| 1819 | when sequence: EqualityLowering.SEQUENCE then | |
| 1820 | _note_lowering_callees(into, sequence.element) | |
| 1821 | when _: EqualityLowering.COMPARER then | |
| 1822 | // The runtime's comparer reaches whatever the type | |
| 1823 | // argument implements, which is not knowable here and | |
| 1824 | // is not a function this body names. | |
| 1825 | else | |
| 1826 | esac | |
| 1827 | si | |
| 1828 | ||
| 1829 | // The whole body of a synthesized `get_hash_code`, hashing the | |
| 1830 | // members its `=~` compares and folding them together. What | |
| 1831 | // each member contributes is decided by the same rule the | |
| 1832 | // comparison is: a member compared element by element hashes | |
| 1833 | // by its count, and one compared more finely than its own hash | |
| 1834 | // answers for contributes nothing. | |
| 1835 | visit_memberwise_hash(memberwise: Trees.Expressions.MEMBERWISE_HASH) is | |
| 1836 | memberwise.compile_expressions_state.value = null | |
| 1837 | ||
| 1838 | let int_type = _innate_symbol_lookup.get_int_type() | |
| 1839 | let location = memberwise.location | |
| 1840 | ||
| 1841 | let owner = _visitor.current_instance_context | |
| 1842 | ||
| 1843 | if !owner? \/ !isa Semantic.Symbols.Classy(owner) then | |
| 1844 | memberwise.compile_expressions_state.value = | |
| 1845 | DUMMY(Semantic.Types.ERROR(), location) | |
| 1846 | ||
| 1847 | return | |
| 1848 | fi | |
| 1849 | ||
| 1850 | let owner_classy = cast Semantic.Symbols.Classy(owner) | |
| 1851 | ||
| 1852 | let self_value = _load_self(owner_classy, location) | |
| 1853 | let get_hash_code = _object_get_hash_code() | |
| 1854 | ||
| 1855 | if !self_value? \/ !get_hash_code? then | |
| 1856 | memberwise.compile_expressions_state.value = | |
| 1857 | DUMMY(Semantic.Types.ERROR(), location) | |
| 1858 | ||
| 1859 | return | |
| 1860 | fi | |
| 1861 | ||
| 1862 | let operands = Collections.LIST[Value]() | |
| 1863 | ||
| 1864 | for i in 0..memberwise.members.count do | |
| 1865 | let member = memberwise.members[i] | |
| 1866 | let member_location = memberwise.member_locations[i] | |
| 1867 | ||
| 1868 | let load = _load_member(self_value, owner_classy, member, member_location) | |
| 1869 | ||
| 1870 | if !load? then | |
| 1871 | continue | |
| 1872 | fi | |
| 1873 | ||
| 1874 | let operand = _compile_hash_operand(load, member_location) | |
| 1875 | ||
| 1876 | // Boxed unconditionally where the member is a value | |
| 1877 | // type: the hash is read through `object`, so an int | |
| 1878 | // field reaches it as a box rather than as a bare | |
| 1879 | // value the call would treat as a reference. | |
| 1880 | operands.add( | |
| 1881 | if operand.is_value_type then | |
| 1882 | IR.Values.BOX(operand) | |
| 1883 | else | |
| 1884 | operand | |
| 1885 | fi | |
| 1886 | ) | |
| 1887 | ||
| 1888 | _note_memberwise_callees( | |
| 1889 | memberwise.called_functions, | |
| 1890 | load.type, | |
| 1891 | load.type, | |
| 1892 | member_location | |
| 1893 | ) | |
| 1894 | od | |
| 1895 | ||
| 1896 | let inherited = _inherited_memberwise_hash(owner_classy) | |
| 1897 | ||
| 1898 | let seed = | |
| 1899 | if let f = inherited then | |
| 1900 | memberwise.called_functions.add(f) | |
| 1901 | ||
| 1902 | IR.Values.Call.INSTANCE( | |
| 1903 | IR.Values.Load.SUPER(owner_classy), | |
| 1904 | f, | |
| 1905 | Collections.LIST[Value](), | |
| 1906 | int_type | |
| 1907 | ) | |
| 1908 | else | |
| 1909 | null | |
| 1910 | fi | |
| 1911 | ||
| 1912 | memberwise.compile_expressions_state.value = | |
| 1913 | IR.Values.HASH_COMBINE(operands, get_hash_code, seed, int_type) | |
| 1914 | si | |
| 1915 | ||
| 1916 | _object_get_hash_code() -> Semantic.Symbols.Function? is | |
| 1917 | let group = _innate_symbol_lookup.get_object_type().find_member("get_hash_code") | |
| 1918 | ||
| 1919 | if !group? \/ !isa Semantic.Symbols.FUNCTION_GROUP(group) then | |
| 1920 | return null | |
| 1921 | fi | |
| 1922 | ||
| 1923 | for function in (cast Semantic.Symbols.FUNCTION_GROUP(group)).functions do | |
| 1924 | if function.arguments.count == 0 then | |
| 1925 | return function | |
| 1926 | fi | |
| 1927 | od | |
| 1928 | ||
| 1929 | return null | |
| 1930 | si | |
| 1931 | ||
| 1932 | // The base's own hash, where the base holds members this type | |
| 1933 | // does not declare - the partner of the comparison delegating | |
| 1934 | // to the base's operator. | |
| 1935 | _inherited_memberwise_hash( | |
| 1936 | owner: Semantic.Symbols.Classy | |
| 1937 | ) -> Semantic.Symbols.Function? is | |
| 1938 | if owner.is_value_type \/ owner.is_variant then | |
| 1939 | return null | |
| 1940 | fi | |
| 1941 | ||
| 1942 | let base = _base_classy(owner) | |
| 1943 | ||
| 1944 | if !base? \/ !_holds_members(base, 0) then | |
| 1945 | return null | |
| 1946 | fi | |
| 1947 | ||
| 1948 | let group = base.find_member("get_hash_code") | |
| 1949 | ||
| 1950 | if !group? \/ !isa Semantic.Symbols.FUNCTION_GROUP(group) then | |
| 1951 | return null | |
| 1952 | fi | |
| 1953 | ||
| 1954 | for function in (cast Semantic.Symbols.FUNCTION_GROUP(group)).functions do | |
| 1955 | if function.arguments.count == 0 /\ !function.is_abstract then | |
| 1956 | return function | |
| 1957 | fi | |
| 1958 | od | |
| 1959 | ||
| 1960 | return null | |
| 1961 | si | |
| 1962 | ||
| 1963 | visit_field_equals(field_equals: Trees.Expressions.FIELD_EQUALS) is | |
| 1964 | field_equals.compile_expressions_state.value = null | |
| 1965 | ||
| 1966 | let left_value = field_equals.left.value | |
| 1967 | let right_value = field_equals.right.value | |
| 1968 | ||
| 1969 | if !left_value? \/ !right_value? then | |
| 1970 | field_equals.compile_expressions_state.value = | |
| 1971 | DUMMY(Semantic.Types.ERROR(), field_equals.location) | |
| 1972 | ||
| 1973 | return | |
| 1974 | fi | |
| 1975 | ||
| 1976 | field_equals.compile_expressions_state.value = | |
| 1977 | _compile_field_equals( | |
| 1978 | left_value, | |
| 1979 | right_value, | |
| 1980 | field_equals.location, | |
| 1981 | field_equals.reports_fallback) | |
| 1982 | si | |
| 1983 | ||
| 1984 | ||
| 1985 | // The value one member of a synthesized `get_hash_code` is | |
| 1986 | // hashed by. .NET requires two values that compare equal to | |
| 1987 | // hash equal, and the member's own `get_hash_code` only keeps | |
| 1988 | // that promise when it answers for the same distinctions the | |
| 1989 | // member's comparison does. | |
| 1990 | // | |
| 1991 | // Three answers. A member compared element-wise is hashed by | |
| 1992 | // its count: two equal sequences agree on that, where the | |
| 1993 | // reference each would hash by does not. A member whose | |
| 1994 | // comparison is finer than its own hash - a type ordered by | |
| 1995 | // `<>` alone, or one declaring `=~` without the | |
| 1996 | // `get_hash_code` that pairs with it - contributes a constant, | |
| 1997 | // since no hash of it would be sound; a hash may ignore what | |
| 1998 | // equality reads, but never the reverse. Everything else is | |
| 1999 | // hashed as it stands. | |
| 2000 | visit_hash_operand(hash_operand: Trees.Expressions.HASH_OPERAND) is | |
| 2001 | hash_operand.compile_expressions_state.value = null | |
| 2002 | ||
| 2003 | let operand = hash_operand.left.value | |
| 2004 | ||
| 2005 | if !operand? then | |
| 2006 | hash_operand.compile_expressions_state.value = | |
| 2007 | DUMMY(Semantic.Types.ERROR(), hash_operand.location) | |
| 2008 | ||
| 2009 | return | |
| 2010 | fi | |
| 2011 | ||
| 2012 | hash_operand.compile_expressions_state.value = | |
| 2013 | _compile_hash_operand(operand, hash_operand.location) | |
| 2014 | si | |
| 2015 | ||
| 2016 | _compile_hash_operand(operand: Value, location: Source.LOCATION) -> Value is | |
| 2017 | let type = operand.type | |
| 2018 | ||
| 2019 | if !type? then | |
| 2020 | return operand | |
| 2021 | fi | |
| 2022 | ||
| 2023 | let inner = _non_optional(type) ?? type | |
| 2024 | let lowering = _choose_equality(inner, inner, location) | |
| 2025 | ||
| 2026 | if !lowering? then | |
| 2027 | return operand | |
| 2028 | fi | |
| 2029 | ||
| 2030 | case lowering | |
| 2031 | when _: EqualityLowering.SEQUENCE then | |
| 2032 | // An absent sequence has no count to read, and a | |
| 2033 | // presence test here would answer a question the | |
| 2034 | // surrounding read already asks, so an optional one | |
| 2035 | // contributes nothing instead. | |
| 2036 | if type.is_optional then | |
| 2037 | return _zero(location) | |
| 2038 | fi | |
| 2039 | ||
| 2040 | let count = _load_property(operand, "count", location) | |
| 2041 | ||
| 2042 | return count ?? _zero(location) | |
| 2043 | when _: EqualityLowering.OPERATOR then | |
| 2044 | return _hashable_or_zero(operand, inner, location) | |
| 2045 | when _: EqualityLowering.ORDER then | |
| 2046 | return _hashable_or_zero(operand, inner, location) | |
| 2047 | else | |
| 2048 | return operand | |
| 2049 | esac | |
| 2050 | si | |
| 2051 | ||
| 2052 | _hashable_or_zero(operand: Value, type: Type, location: Source.LOCATION) -> Value => | |
| 2053 | if _declares_hash_code(type) then | |
| 2054 | operand | |
| 2055 | else | |
| 2056 | _zero(location) | |
| 2057 | fi | |
| 2058 | ||
| 2059 | // Whether the type answers `get_hash_code` for itself rather | |
| 2060 | // than inheriting `object`'s, which hashes by identity and so | |
| 2061 | // says nothing about the values an operator compares. | |
| 2062 | _declares_hash_code(type: Type) -> bool is | |
| 2063 | let member = type.find_member("get_hash_code") | |
| 2064 | ||
| 2065 | if !member? \/ !isa Semantic.Symbols.FUNCTION_GROUP(member) then | |
| 2066 | return false | |
| 2067 | fi | |
| 2068 | ||
| 2069 | let object_symbol = _innate_symbol_lookup.get_object_type().symbol.unspecialized_symbol | |
| 2070 | ||
| 2071 | for function in cast Semantic.Symbols.FUNCTION_GROUP(member).functions do | |
| 2072 | let owner = function.owner | |
| 2073 | ||
| 2074 | if owner? /\ owner.unspecialized_symbol != object_symbol then | |
| 2075 | return true | |
| 2076 | fi | |
| 2077 | od | |
| 2078 | ||
| 2079 | return false | |
| 2080 | si | |
| 2081 | ||
| 2082 | _zero(location: Source.LOCATION) -> Value => | |
| 2083 | IR.Values.Literal.NUMBER(0, _innate_symbol_lookup.get_int_type()) | |
| 2084 | ||
| 2085 | // The comparison a synthesized `=~` runs for one field: the | |
| 2086 | // lowering the field's static type gets anywhere else, with the | |
| 2087 | // null checks written around it where the field is optional. | |
| 2088 | // | |
| 2089 | // Where nothing compares the type, the runtime's comparer is the | |
| 2090 | // only answer left, and a type declared in ghūl source is told | |
| 2091 | // so at the field: it could declare `=~` and does not. Imported | |
| 2092 | // types cannot, so for those the fallback stays silent. | |
| 2093 | _compile_field_equals( | |
| 2094 | left_value: Value, | |
| 2095 | right_value: Value, | |
| 2096 | location: Source.LOCATION, | |
| 2097 | reports_fallback: bool | |
| 2098 | ) -> Value is | |
| 2099 | let left_type = left_value.type | |
| 2100 | let right_type = right_value.type | |
| 2101 | ||
| 2102 | if !left_type? \/ !right_type? then | |
| 2103 | return DUMMY(Semantic.Types.ERROR(), location) | |
| 2104 | fi | |
| 2105 | ||
| 2106 | if left_type.is_optional \/ right_type.is_optional then | |
| 2107 | // The global innates declare their own optional | |
| 2108 | // parameters, so an optional string field is answered | |
| 2109 | // by the operator itself, exactly as a written | |
| 2110 | // `a =~ b` over the same operands would be. | |
| 2111 | let global_value = _try_global_equals_operator(left_value, right_value, location) | |
| 2112 | ||
| 2113 | if global_value? then | |
| 2114 | return global_value | |
| 2115 | fi | |
| 2116 | ||
| 2117 | let null_safe = _build_null_safe_equality(left_value, right_value, location) | |
| 2118 | ||
| 2119 | if null_safe? then | |
| 2120 | return null_safe | |
| 2121 | fi | |
| 2122 | else | |
| 2123 | let lowering = _choose_equality(left_type, right_type, location) | |
| 2124 | ||
| 2125 | if lowering? then | |
| 2126 | if reports_fallback /\ isa EqualityLowering.IDENTITY(lowering) then | |
| 2127 | _warn_equality_fallback(left_type, location, "by reference") | |
| 2128 | elif reports_fallback /\ isa EqualityLowering.COMPARER(lowering) then | |
| 2129 | _warn_equality_fallback(left_type, location, "with the default equality comparer") | |
| 2130 | fi | |
| 2131 | ||
| 2132 | return _build_equality(lowering, left_value, right_value, location) | |
| 2133 | fi | |
| 2134 | fi | |
| 2135 | ||
| 2136 | let comparer_type = _innate_symbol_lookup.get_equality_comparer_type(left_type) | |
| 2137 | ||
| 2138 | if !comparer_type? then | |
| 2139 | _logger.error(location, "cannot compare values of type {left_type}") | |
| 2140 | ||
| 2141 | return DUMMY(Semantic.Types.ERROR(), location) | |
| 2142 | fi | |
| 2143 | ||
| 2144 | if reports_fallback then | |
| 2145 | _warn_equality_fallback(left_type, location, "with the default equality comparer") | |
| 2146 | fi | |
| 2147 | ||
| 2148 | return EQUALITY_COMPARISON( | |
| 2149 | left_value, | |
| 2150 | right_value, | |
| 2151 | comparer_type, | |
| 2152 | _innate_symbol_lookup.get_bool_type()) | |
| 2153 | si | |
| 2154 | ||
| 2155 | // Reported only where the author could act: a type declared in | |
| 2156 | // ghūl source could declare `=~` and does not. Imported types, | |
| 2157 | // tuples, arrays, collection instantiations and function types | |
| 2158 | // cannot declare one, so for those the fallback is the only | |
| 2159 | // semantics available and a report would have no remedy to | |
| 2160 | // point at. | |
| 2161 | _warn_equality_fallback(type: Type, location: Source.LOCATION, how: string) is | |
| 2162 | let inner = _non_optional(type) ?? type | |
| 2163 | ||
| 2164 | if | |
| 2165 | isa Semantic.Symbols.Classy(inner.symbol) /\ | |
| 2166 | !inner.symbol.is_reflected | |
| 2167 | then | |
| 2168 | _logger.warn( | |
| 2169 | location, | |
| 2170 | "synthesized-equality-fallback", | |
| 2171 | "{type} defines no =~, so this field compares {how}") | |
| 2172 | fi | |
| 2173 | si | |
| 2174 | ||
| 2175 | ||
| 2176 | // A `=~` operator in scope as a global — the scalar and string | |
| 2177 | // innates. Returns null when nothing in scope answers for these | |
| 2178 | // operand types. | |
| 2179 | // The global `=~` that would be called for two operands of the | |
| 2180 | // given types, if any. Resolution only - nothing is recorded | |
| 2181 | // and no call is built, so a caller can ask the question and | |
| 2182 | // then decline. | |
| 2183 | _find_global_equals_operator( | |
| 2184 | left_type: Type, | |
| 2185 | right_type: Type, | |
| 2186 | location: Source.LOCATION | |
| 2187 | ) -> Semantic.Symbols.Function? is | |
| 2188 | let global_symbol = _visitor.find(Trees.Identifiers.Identifier(location, "=~")) | |
| 2189 | ||
| 2190 | if !global_symbol? \/ !isa Semantic.Symbols.FUNCTION_GROUP(global_symbol) then | |
| 2191 | return null | |
| 2192 | fi | |
| 2193 | ||
| 2194 | let overload_result = | |
| 2195 | _resolve_silently( | |
| 2196 | location, | |
| 2197 | cast Semantic.Symbols.FUNCTION_GROUP(global_symbol), | |
| 2198 | Collections.LIST[Type]([left_type, right_type]), | |
| 2199 | false) | |
| 2200 | ||
| 2201 | if !overload_result? then | |
| 2202 | return null | |
| 2203 | fi | |
| 2204 | ||
| 2205 | return overload_result.function | |
| 2206 | si | |
| 2207 | ||
| 2208 | _try_global_equals_operator( | |
| 2209 | left_value: Value, | |
| 2210 | right_value: Value, | |
| 2211 | location: Source.LOCATION | |
| 2212 | ) -> Value? is | |
| 2213 | let function = | |
| 2214 | _find_global_equals_operator(left_value.type!, right_value.type!, location) | |
| 2215 | ||
| 2216 | if !function? then | |
| 2217 | return null | |
| 2218 | fi | |
| 2219 | ||
| 2220 | _symbol_use_locations.add_symbol_use(location, function) | |
| 2221 | ||
| 2222 | let value = | |
| 2223 | function.call( | |
| 2224 | location, | |
| 2225 | null, | |
| 2226 | Collections.LIST[Value]([left_value, right_value]), | |
| 2227 | null, | |
| 2228 | _function_caller) | |
| 2229 | ||
| 2230 | if isa Call.INNATE(value) then | |
| 2231 | let innate_value = value | |
| 2232 | ||
| 2233 | innate_value.actual_operation = "=~" | |
| 2234 | ||
| 2235 | return innate_value.lower() | |
| 2236 | fi | |
| 2237 | ||
| 2238 | return value | |
| 2239 | si | |
| 2240 | ||
| 2241 | // `a =~ b` where an operand is optional. Resolve against the | |
| 2242 | // operands' non-optional types and write the null checks | |
| 2243 | // around the call. | |
| 2244 | // | |
| 2245 | // An absent left operand is always answered here: there is no | |
| 2246 | // receiver to dispatch on. An absent right operand is answered | |
| 2247 | // here only when the operator declares its parameter | |
| 2248 | // non-optional and so could never have been handed one. | |
| 2249 | // | |
| 2250 | // Answers null for anything else, leaving the operands to | |
| 2251 | // resolve however they did before. | |
| 2252 | // `a =~ b` where an operand is optional. Delegates the null-safe | |
| 2253 | // building to _build_null_safe_equality (shared with `case`'s | |
| 2254 | // value-equality tests) and applies the `!~` negation the AST | |
| 2255 | // spelling carries. Only `=~` is null-safe here; the binary | |
| 2256 | // visitor's main body handles the non-optional path with its | |
| 2257 | // full diagnostics and retry, so this returns null unless an | |
| 2258 | // operand is optional. | |
| 2259 | _try_null_safe_equality( | |
| 2260 | binary: Trees.Expressions.BINARY, | |
| 2261 | left_value: Value, | |
| 2262 | right_value: Value | |
| 2263 | ) -> Value? is | |
| 2264 | if !(binary.operation.name =~ "=~") then | |
| 2265 | return null | |
| 2266 | fi | |
| 2267 | ||
| 2268 | let left_type = left_value.type | |
| 2269 | let right_type = right_value.type | |
| 2270 | ||
| 2271 | if | |
| 2272 | (!left_type? \/ !left_type.is_optional) /\ | |
| 2273 | (!right_type? \/ !right_type.is_optional) | |
| 2274 | then | |
| 2275 | return null | |
| 2276 | fi | |
| 2277 | ||
| 2278 | let result = _build_null_safe_equality(left_value, right_value, binary.location) | |
| 2279 | ||
| 2280 | if !result? then | |
| 2281 | return null | |
| 2282 | fi | |
| 2283 | ||
| 2284 | if binary.actual_operation =~ "!~" then | |
| 2285 | let negated = IR.Values.BLOCK(_innate_symbol_lookup.get_bool_type()) | |
| 2286 | negated.add(NOT(result)) | |
| 2287 | negated.close() | |
| 2288 | return negated | |
| 2289 | fi | |
| 2290 | ||
| 2291 | return result | |
| 2292 | si | |
| 2293 | ||
| 2294 | // Build a null-safe `=~` test for two operands, at least one of | |
| 2295 | // which is optional. Resolves the left type's `=~` against the | |
| 2296 | // operands' non-optional inner types and writes the null checks | |
| 2297 | // around the call: an absent left operand is always answered | |
| 2298 | // here (no receiver to dispatch on), an absent right operand is | |
| 2299 | // answered here unless the operator declares its parameter | |
| 2300 | // optional and so could be handed one. Returns null when the | |
| 2301 | // gate rejects the operands or operator, or no `=~` resolves. | |
| 2302 | // | |
| 2303 | // Extracted from _try_null_safe_equality so `case` value-equality | |
| 2304 | // (see _try_equality_test) reuses the same lowering rather than | |
| 2305 | // duplicating it. | |
| 2306 | _build_null_safe_equality( | |
| 2307 | left_value: Value, | |
| 2308 | right_value: Value, | |
| 2309 | location: Source.LOCATION | |
| 2310 | ) -> Value? is | |
| 2311 | let left_type = left_value.type | |
| 2312 | let right_type = right_value.type | |
| 2313 | ||
| 2314 | if !NULL_SAFE_EQUALITY_GATE.accepts_operands(left_type, right_type) then | |
| 2315 | return null | |
| 2316 | fi | |
| 2317 | ||
| 2318 | let left_inner = _non_optional(left_type!) | |
| 2319 | let right_inner = _non_optional(right_type!) | |
| 2320 | ||
| 2321 | if !left_inner? \/ !right_inner? then | |
| 2322 | return null | |
| 2323 | fi | |
| 2324 | ||
| 2325 | let comparison = | |
| 2326 | _null_safe_comparison(left_type, right_type, left_inner, right_inner, location) | |
| 2327 | ||
| 2328 | if !comparison? then | |
| 2329 | return null | |
| 2330 | fi | |
| 2331 | ||
| 2332 | let guards_argument = | |
| 2333 | if let operator: EqualityLowering.OPERATOR = comparison then | |
| 2334 | NULL_SAFE_EQUALITY_GATE.guards_argument(operator.function) | |
| 2335 | elif let order: EqualityLowering.ORDER = comparison then | |
| 2336 | NULL_SAFE_EQUALITY_GATE.guards_argument(order.function) | |
| 2337 | else | |
| 2338 | // The comparer, a sequence and identity all take | |
| 2339 | // two present values, so an absent one has to be | |
| 2340 | // answered out here. | |
| 2341 | true | |
| 2342 | fi | |
| 2343 | ||
| 2344 | // With an operator that answers for an absent argument | |
| 2345 | // itself, a present left operand needs nothing doing: the | |
| 2346 | // call already resolves and already reaches the body. | |
| 2347 | // | |
| 2348 | // Except for a value-shape argument, which is answered here | |
| 2349 | // whatever the operator declares. Declining on the strength | |
| 2350 | // of the left operand alone would make that turn on | |
| 2351 | // something unrelated to it, so the same comparison would | |
| 2352 | // answer differently for an optional left and a present | |
| 2353 | // one. | |
| 2354 | if | |
| 2355 | !left_type.is_optional /\ | |
| 2356 | !guards_argument /\ | |
| 2357 | !(right_type.is_optional /\ right_type.is_value_type) | |
| 2358 | then | |
| 2359 | return null | |
| 2360 | fi | |
| 2361 | ||
| 2362 | let bool_type = _innate_symbol_lookup.get_bool_type() | |
| 2363 | let block = IR.Values.BLOCK(bool_type) | |
| 2364 | ||
| 2365 | // Each operand is read up to three times - by its own | |
| 2366 | // presence test, and by the call - so spill anything that | |
| 2367 | // is not already a repeatable load. A value-shape optional | |
| 2368 | // additionally needs its address, which a spilled temp has | |
| 2369 | // and an expression does not. | |
| 2370 | let load_left = left_value.get_temp_copier(block, "equality_left") | |
| 2371 | let load_right = right_value.get_temp_copier(block, "equality_right") | |
| 2372 | ||
| 2373 | let operand = | |
| 2374 | OPTIONAL_OPERAND(IoC.CONTAINER.instance.symbol_loader, bool_type) | |
| 2375 | ||
| 2376 | if | |
| 2377 | !operand.can_split(location, load_left()) \/ | |
| 2378 | !operand.can_split(location, load_right()) | |
| 2379 | then | |
| 2380 | return null | |
| 2381 | fi | |
| 2382 | ||
| 2383 | // A value-shape argument is guarded whatever the operator | |
| 2384 | // declares: its parameter is a bare `T` at IL, so there is | |
| 2385 | // no absent value to hand a body in the first place. | |
| 2386 | let guards = guards_argument \/ OPTIONAL_OPERAND.must_be_guarded(load_right()) | |
| 2387 | ||
| 2388 | let left_payload = operand.payload(location, load_left()) | |
| 2389 | let right_payload = operand.payload(location, load_right()) | |
| 2390 | ||
| 2391 | if !left_payload? \/ !right_payload? then | |
| 2392 | return null | |
| 2393 | fi | |
| 2394 | ||
| 2395 | let call = _build_equality(comparison, left_payload, right_payload, location) | |
| 2396 | ||
| 2397 | let result = | |
| 2398 | IR.Values.NULL_SAFE_EQUALITY( | |
| 2399 | operand.presence(location, load_left()), | |
| 2400 | operand.presence(location, load_right()), | |
| 2401 | call, | |
| 2402 | guards, | |
| 2403 | bool_type | |
| 2404 | ) | |
| 2405 | ||
| 2406 | block.add(result) | |
| 2407 | block.close() | |
| 2408 | ||
| 2409 | return block | |
| 2410 | si | |
| 2411 | ||
| 2412 | // Which comparison a null-safe `=~` wraps: the one two present | |
| 2413 | // values of the inner types get. | |
| 2414 | // | |
| 2415 | // An operator that accepts the operands as they stand is left | |
| 2416 | // alone: declaring an optional parameter is how one says it | |
| 2417 | // answers for an absent operand itself, and wrapping it would | |
| 2418 | // take that decision away. Null for that, and for operands | |
| 2419 | // nothing compares, leaving the comparison to resolve as it | |
| 2420 | // did. | |
| 2421 | _null_safe_comparison( | |
| 2422 | left_type: Type, | |
| 2423 | right_type: Type, | |
| 2424 | left_inner: Type, | |
| 2425 | right_inner: Type, | |
| 2426 | location: Source.LOCATION | |
| 2427 | ) -> EqualityLowering? is | |
| 2428 | if _find_global_equals_operator(left_type, right_type, location)? then | |
| 2429 | return null | |
| 2430 | fi | |
| 2431 | ||
| 2432 | let lowering = _choose_equality(left_inner, right_inner, location) | |
| 2433 | ||
| 2434 | // A reference of a class declaring neither operator is not | |
| 2435 | // compared by identity from a written `=~`, null-safe or | |
| 2436 | // not; a synthesized member reaches identity through the | |
| 2437 | // field path instead. | |
| 2438 | if lowering? /\ isa EqualityLowering.IDENTITY(lowering) then | |
| 2439 | return null | |
| 2440 | fi | |
| 2441 | ||
| 2442 | return lowering | |
| 2443 | si | |
| 2444 | ||
| 2445 | ||
| 2446 | _try_equality_test( | |
| 2447 | left_value: Value, | |
| 2448 | right_value: Value, | |
| 2449 | op_name: string, | |
| 2450 | location: Source.LOCATION | |
| 2451 | ) -> Value? is | |
| 2452 | let left_type = left_value.type | |
| 2453 | let right_type = right_value.type | |
| 2454 | ||
| 2455 | if !left_type? \/ !right_type? then | |
| 2456 | return null | |
| 2457 | fi | |
| 2458 | ||
| 2459 | let optional = left_type.is_optional \/ right_type.is_optional | |
| 2460 | ||
| 2461 | if op_name =~ "=~" then | |
| 2462 | if optional then | |
| 2463 | let null_safe = _build_null_safe_equality(left_value, right_value, location) | |
| 2464 | ||
| 2465 | if null_safe? then | |
| 2466 | return null_safe | |
| 2467 | fi | |
| 2468 | ||
| 2469 | // An instance `=~` the gate declined (a static | |
| 2470 | // operator like string's op_Equality, or one hidden | |
| 2471 | // from operator resolution) reaches the free-function | |
| 2472 | // `Ghul.=~`, which is null-safe over optionals - the | |
| 2473 | // same call the `=~` expression makes for these types. | |
| 2474 | return _try_global_equals_operator(left_value, right_value, location) | |
| 2475 | fi | |
| 2476 | ||
| 2477 | let lowering = _choose_equality(left_type, right_type, location) | |
| 2478 | ||
| 2479 | if !lowering? \/ isa EqualityLowering.IDENTITY(lowering) then | |
| 2480 | return null | |
| 2481 | fi | |
| 2482 | ||
| 2483 | return _build_equality(lowering, left_value, right_value, location) | |
| 2484 | fi | |
| 2485 | ||
| 2486 | if op_name =~ "<>" then | |
| 2487 | if optional then | |
| 2488 | return null | |
| 2489 | fi | |
| 2490 | ||
| 2491 | let order = _find_order_operator(left_type, right_type, location) | |
| 2492 | ||
| 2493 | if !order? then | |
| 2494 | return null | |
| 2495 | fi | |
| 2496 | ||
| 2497 | return _build_equality(EqualityLowering.ORDER(order), left_value, right_value, location) | |
| 2498 | fi | |
| 2499 | ||
| 2500 | return null | |
| 2501 | si | |
| 2502 | ||
| 2503 | ||
| 2504 | _non_optional(type: Type) -> Type? => | |
| 2505 | if type.is_optional then | |
| 2506 | type.optional_inner_type | |
| 2507 | else | |
| 2508 | type | |
| 2509 | fi | |
| 2510 | ||
| 2511 | // Whether an operator takes the left operand as its receiver: an | |
| 2512 | // instance member, or an innate declared with one, such as an | |
| 2513 | // enum's `=~`. | |
| 2514 | _takes_receiver(function: Semantic.Symbols.Function) -> bool => | |
| 2515 | function.is_instance \/ isa Semantic.Symbols.INNATE_METHOD(function) | |
| 2516 | ||
| 2517 | // The instance operators in a type's group under the operator's | |
| 2518 | // name, which take the left operand as their receiver. A static | |
| 2519 | // operator in the same group takes both operands as arguments | |
| 2520 | // and is a candidate on the other route, so it is left out here | |
| 2521 | // - a unary static would otherwise match the right operand alone. | |
| 2522 | _instance_operator_candidates( | |
| 2523 | location: Source.LOCATION, | |
| 2524 | name: string, | |
| 2525 | member: Semantic.Symbols.Symbol? | |
| 2526 | ) -> Semantic.Symbols.FUNCTION_GROUP? is | |
| 2527 | let group = cast Semantic.Symbols.FUNCTION_GROUP?(member) | |
| 2528 | ||
| 2529 | if !group? then | |
| 2530 | return null | |
| 2531 | fi | |
| 2532 | ||
| 2533 | if group.functions |> Ghul.Pipes.all(f => _takes_receiver(f)) then | |
| 2534 | return group | |
| 2535 | fi | |
| 2536 | ||
| 2537 | let result = Semantic.Symbols.FUNCTION_GROUP(location, _symbol_table.current_scope, name) | |
| 2538 | ||
| 2539 | for function in group.functions do | |
| 2540 | if _takes_receiver(function) then | |
| 2541 | result.add(function) | |
| 2542 | fi | |
| 2543 | od | |
| 2544 | ||
| 2545 | return if result.is_empty then null else result fi | |
| 2546 | si | |
| 2547 | ||
| 2548 | // The candidates for an operator taking its operands as | |
| 2549 | // arguments: whatever is in scope under the operator's name - | |
| 2550 | // global operators, and members brought in by `use` - plus the | |
| 2551 | // static operators each operand's own type declares, so a type | |
| 2552 | // that declares `+` for itself supplies it wherever one of its | |
| 2553 | // values is an operand. Instance operators are the left | |
| 2554 | // operand's to resolve as a receiver and are left out here. Null | |
| 2555 | // when nothing answers to the name at all. | |
| 2556 | // | |
| 2557 | // The scope group is handed back as it stands when the operand | |
| 2558 | // types add nothing, so a group that is copied is always one | |
| 2559 | // that needed combining. | |
| 2560 | _static_operator_candidates( | |
| 2561 | location: Source.LOCATION, | |
| 2562 | name: string, | |
| 2563 | operand_types: Collections.List[Type] | |
| 2564 | ) -> Semantic.Symbols.FUNCTION_GROUP? is | |
| 2565 | let scope_group = cast Semantic.Symbols.FUNCTION_GROUP?(_visitor.find(name)) | |
| 2566 | let result: Semantic.Symbols.FUNCTION_GROUP? mut = scope_group | |
| 2567 | let seen = Collections.LIST[Semantic.Symbols.FUNCTION_GROUP]() | |
| 2568 | ||
| 2569 | for operand_type in operand_types do | |
| 2570 | let inner = _non_optional(operand_type) ?? operand_type | |
| 2571 | ||
| 2572 | // A type parameter reaches its bounds' operators through | |
| 2573 | // every bound that inherits them, and a static one is only | |
| 2574 | // resolvable once brought into scope by name. | |
| 2575 | if inner.is_type_variable then | |
| 2576 | continue | |
| 2577 | fi | |
| 2578 | ||
| 2579 | let group = cast Semantic.Symbols.FUNCTION_GROUP?(inner.find_member(name)) | |
| 2580 | ||
| 2581 | if !group? \/ seen.contains(group) then | |
| 2582 | continue | |
| 2583 | fi | |
| 2584 | ||
| 2585 | seen.add(group) | |
| 2586 | ||
| 2587 | for function in group.functions do | |
| 2588 | if _takes_receiver(function) \/ function.is_hidden_from_operator_resolution then | |
| 2589 | continue | |
| 2590 | fi | |
| 2591 | ||
| 2592 | if !result? \/ result == scope_group then | |
| 2593 | let combined = Semantic.Symbols.FUNCTION_GROUP(location, _symbol_table.current_scope, name) | |
| 2594 | ||
| 2595 | if scope_group? then | |
| 2596 | combined.add(scope_group) | |
| 2597 | fi | |
| 2598 | ||
| 2599 | result = combined | |
| 2600 | fi | |
| 2601 | ||
| 2602 | if !(result.functions |> Ghul.Pipes.any(f => f == function)) then | |
| 2603 | result.add(function) | |
| 2604 | fi | |
| 2605 | od | |
| 2606 | od | |
| 2607 | ||
| 2608 | return result | |
| 2609 | si | |
| 2610 | ||
| 2611 | // Resolve an operator overload under speculation, so a failed | |
| 2612 | // resolution (no matching overload) leaves no diagnostics: the | |
| 2613 | // `case` path treats "no operator" as "fall back to a raw | |
| 2614 | // compare", not an error. Mirrors the speculation | |
| 2615 | // _resolve_with_retry gives the `=~` expression. | |
| 2616 | _resolve_silently( | |
| 2617 | location: Source.LOCATION, | |
| 2618 | group: Semantic.Symbols.FUNCTION_GROUP, | |
| 2619 | argument_types: Collections.LIST[Type], | |
| 2620 | want_instance: bool | |
| 2621 | ) -> Semantic.OVERLOAD_RESOLVE_RESULT? is | |
| 2622 | RETRY_SITE_STATS.note("operators.resolve_silently") | |
| 2623 | let use snapshot = _logger.speculate_then_backtrack() | |
| 2624 | ||
| 2625 | let result = | |
| 2626 | _overload_resolver.resolve(location, group, argument_types, false, want_instance, false) | |
| 2627 | ||
| 2628 | snapshot.backtrack() | |
| 2629 | ||
| 2630 | return result | |
| 2631 | si | |
| 2632 | ||
| 2633 | // `a ?? b` — short-circuit null-coalesce. Result type is the | |
| 2634 | // LUB of the left's underlying type and the right's type, with | |
| 2635 | // `?` re-applied iff the right is itself optional. Right is | |
| 2636 | // evaluated only when left is null. | |
| 2637 | _visit_null_coalesce(binary: Trees.Expressions.BINARY) is | |
| 2638 | let left_value = binary.left.value! | |
| 2639 | let right_value = binary.right.value! | |
| 2640 | ||
| 2641 | ||
| 2642 | left_value.check_is_consumable(_logger, binary.left.location) | |
| 2643 | right_value.check_is_consumable(_logger, binary.right.location) | |
| 2644 | ||
| 2645 | let left_type = left_value.type | |
| 2646 | let right_type = right_value.type | |
| 2647 | ||
| 2648 | if !left_type? \/ left_type.is_error \/ !right_type? \/ right_type.is_error then | |
| 2649 | binary.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), binary.location) | |
| 2650 | return | |
| 2651 | fi | |
| 2652 | ||
| 2653 | // A left operand whose type is still a placeholder may yet | |
| 2654 | // settle optional, so it cannot stand in for the whole | |
| 2655 | // expression the way a non-optional operand does: the | |
| 2656 | // coalesce waits for a later walk, and nothing learns the | |
| 2657 | // placeholder's type from the expression meanwhile. | |
| 2658 | if left_type.is_inferred then | |
| 2659 | // A local that has held `null` and falls back to a value | |
| 2660 | // here holds that value's type when present. | |
| 2661 | if | |
| 2662 | let placeholder: Semantic.Types.INFERRED_VARIABLE_TYPE = left_type /\ | |
| 2663 | placeholder.origin.has_seen_null /\ | |
| 2664 | right_type.is_settled /\ | |
| 2665 | !right_type.is_null | |
| 2666 | then | |
| 2667 | let fallback = right_type.optional_inner_type ?? right_type | |
| 2668 | ||
| 2669 | if Semantic.INFERENCE_TRACE.add_lower_bound("operators.null_coalesce_fallback", placeholder.origin, fallback) then | |
| 2670 | _logger.mark_consumed_any() | |
| 2671 | fi | |
| 2672 | fi | |
| 2673 | ||
| 2674 | binary.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), binary.location) | |
| 2675 | return | |
| 2676 | fi | |
| 2677 | ||
| 2678 | // Flow analysis routinely narrows a declared `T?` to `T` | |
| 2679 | // after a non-null assignment. Treating that as an error | |
| 2680 | // would reject defensive `present ?? fallback` patterns | |
| 2681 | // — degrade to just emitting `left` instead, matching how | |
| 2682 | // `?.` falls back to `.` when the receiver is non-optional. | |
| 2683 | if !left_type.is_optional then | |
| 2684 | binary.compile_expressions_state.value = left_value | |
| 2685 | return | |
| 2686 | fi | |
| 2687 | ||
| 2688 | let left_inner = left_type.optional_inner_type | |
| 2689 | ||
| 2690 | if !left_inner? then | |
| 2691 | binary.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), binary.location) | |
| 2692 | return | |
| 2693 | fi | |
| 2694 | ||
| 2695 | let right_is_optional = right_type.is_optional | |
| 2696 | ||
| 2697 | let right_inner = | |
| 2698 | if right_is_optional then | |
| 2699 | right_type.optional_inner_type | |
| 2700 | else | |
| 2701 | right_type | |
| 2702 | fi | |
| 2703 | ||
| 2704 | let lub = LEAST_UPPER_BOUND_MAP() | |
| 2705 | ||
| 2706 | lub.add(left_inner) | |
| 2707 | ||
| 2708 | if right_inner? then | |
| 2709 | lub.add(right_inner) | |
| 2710 | fi | |
| 2711 | ||
| 2712 | let result_inner = lub.get_result() | |
| 2713 | ||
| 2714 | if !result_inner? then | |
| 2715 | _logger.error(binary.location, "no common type for ?? operands {left_type} and {right_type}") | |
| 2716 | binary.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), binary.location) | |
| 2717 | return | |
| 2718 | fi | |
| 2719 | ||
| 2720 | // The result's optional kind derives from the LUB of the | |
| 2721 | // inner types, not from either operand: reference inner → | |
| 2722 | // flagged reference optional, value inner → NULLABLE, and | |
| 2723 | // a type-variable inner keeps the left's MAYBE carrier — | |
| 2724 | // the only lowering an unconstrained T? has. The operands | |
| 2725 | // may each be a different kind of optional; each arm | |
| 2726 | // coerces to the canonical result. | |
| 2727 | let result_type = | |
| 2728 | if !right_is_optional then | |
| 2729 | result_inner | |
| 2730 | elif result_inner.is_type_variable then | |
| 2731 | left_type | |
| 2732 | else | |
| 2733 | COMPILE_ACCESS.build_optional_type(result_inner, _innate_symbol_lookup) | |
| 2734 | fi | |
| 2735 | ||
| 2736 | let absent_arm = _coerce_coalesce_arm(right_value, result_type) | |
| 2737 | ||
| 2738 | if !left_type.is_value_type then | |
| 2739 | binary.compile_expressions_state.value = NULL_COALESCE(left_value, absent_arm, result_type) | |
| 2740 | return | |
| 2741 | fi | |
| 2742 | ||
| 2743 | // Value-shape left — NULLABLE[T] or MAYBE[T]: spill the | |
| 2744 | // receiver to a local and drive the presence test and | |
| 2745 | // payload extract through its address, mirroring the | |
| 2746 | // `?.` lowering. | |
| 2747 | let has_value_member = left_type.find_member("has_value") | |
| 2748 | let value_member = left_type.find_member("value") | |
| 2749 | ||
| 2750 | if !has_value_member? \/ !value_member? then | |
| 2751 | _logger.poison(binary.location, "?? left operand {left_type} missing has_value or value member") | |
| 2752 | binary.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), binary.location) | |
| 2753 | return | |
| 2754 | fi | |
| 2755 | ||
| 2756 | let address_stand_in = IR.Values.STACK_TOP_ADDRESS(left_type) | |
| 2757 | let symbol_loader = IoC.CONTAINER.instance.symbol_loader | |
| 2758 | ||
| 2759 | let presence_test = has_value_member.load(binary.left.location, address_stand_in, symbol_loader) | |
| 2760 | let value_extract = value_member.load(binary.left.location, address_stand_in, symbol_loader) | |
| 2761 | ||
| 2762 | let present_arm = _coerce_coalesce_arm(IR.Values.STACK_TOP(left_inner), result_type) | |
| 2763 | ||
| 2764 | binary.compile_expressions_state.value = | |
| 2765 | IR.Values.NULL_COALESCE_VALUE( | |
| 2766 | left_value, | |
| 2767 | presence_test, | |
| 2768 | value_extract, | |
| 2769 | present_arm, | |
| 2770 | absent_arm, | |
| 2771 | result_type | |
| 2772 | ) | |
| 2773 | si | |
| 2774 | ||
| 2775 | // Bring one arm of `??` to the result type: T → T? wrapping | |
| 2776 | // (Nullable / MAYBE construction), MAYBE → reference-optional | |
| 2777 | // payload load, NULLABLE ↔ MAYBE pass through unchanged (the | |
| 2778 | // layouts are identical), and a value-typed arm boxes when | |
| 2779 | // the LUB widened the result to a reference type. | |
| 2780 | _coerce_coalesce_arm(value: IR.Values.Value, result_type: Semantic.Types.Type) -> IR.Values.Value is | |
| 2781 | let coerced = _value_boxer.wrap_if_needed(value, result_type)! | |
| 2782 | ||
| 2783 | if !result_type.is_value_type /\ coerced.type? /\ coerced.type.is_value_type then | |
| 2784 | return IR.Values.BOX(coerced) | |
| 2785 | fi | |
| 2786 | ||
| 2787 | return coerced | |
| 2788 | si | |
| 2789 | ||
| 2790 | // An index argument takes its type from the indexer resolution | |
| 2791 | // settles on, so it walks under a speculation for the same | |
| 2792 | // reason an operator operand does. The receiver is not a | |
| 2793 | // candidate: an untyped one has no members for the indexer to | |
| 2794 | // be found on, so there is nothing to resolve against. | |
| 2795 | pre_index(index: Trees.Expressions.INDEX) -> bool is | |
| 2796 | if index.index.awaits_context_type then | |
| 2797 | _deferred_operands.add(DEFERRED_OPERANDS(index)) | |
| 2798 | ||
| 2799 | RETRY_SITE_STATS.note("operators.pre_index_deferred") | |
| 2800 | _logger.speculate() | |
| 2801 | _flow.speculate() | |
| 2802 | fi | |
| 2803 | ||
| 2804 | return false | |
| 2805 | si | |
| 2806 | ||
| 2807 | visit_index(index: Trees.Expressions.INDEX) is | |
| 2808 | if !_deferred_for(index)? then | |
| 2809 | _visit_index(index) | |
| 2810 | ||
| 2811 | return | |
| 2812 | fi | |
| 2813 | ||
| 2814 | try | |
| 2815 | _visit_index(index) | |
| 2816 | finally | |
| 2817 | _deferred_operands.remove_at(_deferred_operands.count - 1) | |
| 2818 | ||
| 2819 | _flow.commit() | |
| 2820 | _logger.commit() | |
| 2821 | yrt | |
| 2822 | si | |
| 2823 | ||
| 2824 | _visit_index(index: Trees.Expressions.INDEX) is | |
| 2825 | let existing_value = index.value | |
| 2826 | let need_store = existing_value? /\ existing_value.is_need_store | |
| 2827 | ||
| 2828 | if index.left.value? /\ index.index.value? then | |
| 2829 | let left_value = index.left.value | |
| 2830 | let type = left_value.type | |
| 2831 | ||
| 2832 | if type == null \/ type.is_error then | |
| 2833 | _logger.poison(index.left.location, "index left has no type") | |
| 2834 | ||
| 2835 | index.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), index.location) | |
| 2836 | return | |
| 2837 | fi | |
| 2838 | ||
| 2839 | // Indexable inference: an `INFERRED_VARIABLE_TYPE` | |
| 2840 | // receiver records an INDEX_CONSTRAINT carrying the | |
| 2841 | // index expression's type, so the body-retry loop | |
| 2842 | // can filter candidates to indexable types. Skip | |
| 2843 | // the "cannot index" hard error path on placeholder | |
| 2844 | // — the existing speculate/roll-back would discard | |
| 2845 | // it on retry but emitting it is noise; soft-error | |
| 2846 | // out to DUMMY(ERROR) instead. | |
| 2847 | let index_type = index.index?.value?.type | |
| 2848 | ||
| 2849 | if | |
| 2850 | isa Semantic.Types.INFERRED_VARIABLE_TYPE(type) /\ | |
| 2851 | index_type? | |
| 2852 | then | |
| 2853 | let placeholder = type | |
| 2854 | ||
| 2855 | // An index whose own type is not settled yet says | |
| 2856 | // only that the receiver is indexed by something | |
| 2857 | // unknown, and a constraint is never withdrawn - so | |
| 2858 | // recording it here judges every candidate the | |
| 2859 | // receiver later settles on against an index type | |
| 2860 | // that no longer describes the index. Wait for it | |
| 2861 | // instead: what the index resolves to is the | |
| 2862 | // deduction this constraint is meant to carry. | |
| 2863 | if index_type.is_settled then | |
| 2864 | let constraint = Semantic.INDEX_CONSTRAINT(index_type) | |
| 2865 | ||
| 2866 | _logger.mark_consumed_any_if(Semantic.INFERENCE_TRACE.add_constraint("operators.index", placeholder.origin, constraint)) | |
| 2867 | else | |
| 2868 | Semantic.OBLIGATIONS.defer("index", index_type, index.location) | |
| 2869 | fi | |
| 2870 | ||
| 2871 | index.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), index.location) | |
| 2872 | return | |
| 2873 | fi | |
| 2874 | ||
| 2875 | if !isa Semantic.Types.NAMED(type) then | |
| 2876 | _logger.error(index.left.location, "cannot index {type}") | |
| 2877 | ||
| 2878 | index.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), index.location) | |
| 2879 | return | |
| 2880 | fi | |
| 2881 | ||
| 2882 | let named_type = type | |
| 2883 | ||
| 2884 | let function_name: string mut | |
| 2885 | let arguments: Collections.LIST[Value] mut | |
| 2886 | let argument_types: Collections.LIST[Type] mut | |
| 2887 | ||
| 2888 | let index_value = index.index.value! | |
| 2889 | ||
| 2890 | // An index with no type has nothing for the indexer's | |
| 2891 | // overload resolution to match against. | |
| 2892 | if !index_value.type? then | |
| 2893 | index.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), index.location) | |
| 2894 | return | |
| 2895 | fi | |
| 2896 | ||
| 2897 | if need_store then | |
| 2898 | function_name = Semantic.Symbols.INDEXER_NAMES.assign | |
| 2899 | ||
| 2900 | let need_store_value = cast Need.STORE?(index.value)!.value | |
| 2901 | ||
| 2902 | // The value being stored has no type when its own | |
| 2903 | // expression failed to resolve, which is reported | |
| 2904 | // where it is written. | |
| 2905 | if !need_store_value.type? then | |
| 2906 | index.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), index.location) | |
| 2907 | return | |
| 2908 | fi | |
| 2909 | ||
| 2910 | arguments = Collections.LIST[Value]([index_value, need_store_value]) | |
| 2911 | argument_types = Collections.LIST[Type]([index_value.type!, need_store_value.type!]) | |
| 2912 | else | |
| 2913 | function_name = Semantic.Symbols.INDEXER_NAMES.read | |
| 2914 | arguments = Collections.LIST[Value]([index_value]) | |
| 2915 | argument_types = Collections.LIST[Type]([index_value.type!]) | |
| 2916 | fi | |
| 2917 | ||
| 2918 | let symbol = named_type.find_member(function_name) | |
| 2919 | ||
| 2920 | if symbol == null then | |
| 2921 | if need_store then | |
| 2922 | if named_type.find_member(Semantic.Symbols.INDEXER_NAMES.read)? then | |
| 2923 | _logger.error(index.location, "indexer is read-only in {type}") | |
| 2924 | else | |
| 2925 | _logger.error(index.location, "no indexer found in {type}") | |
| 2926 | fi | |
| 2927 | else | |
| 2928 | _logger.error(index.location, "no indexer found in {type}") | |
| 2929 | fi | |
| 2930 | ||
| 2931 | index.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), index.location) | |
| 2932 | return | |
| 2933 | fi | |
| 2934 | ||
| 2935 | if !isa Semantic.Symbols.FUNCTION_GROUP(symbol) then | |
| 2936 | _logger.poison(index.index.location, "indexer is not a function group: {symbol}") | |
| 2937 | fi | |
| 2938 | ||
| 2939 | let overload_result: Semantic.OVERLOAD_RESOLVE_RESULT? mut | |
| 2940 | ||
| 2941 | RETRY_SITE_STATS.note("operators.index_resolve") | |
| 2942 | let use logger_snapshot = _logger.speculate_then_backtrack() | |
| 2943 | ||
| 2944 | overload_result = | |
| 2945 | _overload_resolver.resolve( | |
| 2946 | index.location, | |
| 2947 | cast Semantic.Symbols.FUNCTION_GROUP?(symbol)!, | |
| 2948 | argument_types, | |
| 2949 | false, | |
| 2950 | true, | |
| 2951 | false | |
| 2952 | ) | |
| 2953 | ||
| 2954 | logger_snapshot.backtrack() | |
| 2955 | ||
| 2956 | if overload_result == null then | |
| 2957 | if !need_store /\ _try_range_slice(index, left_value, index_value, argument_types[0]) then | |
| 2958 | return | |
| 2959 | fi | |
| 2960 | ||
| 2961 | // An argument that is already an error has been | |
| 2962 | // reported where it was written. | |
| 2963 | if argument_types[0].is_error \/ (need_store /\ argument_types[1].is_error) then | |
| 2964 | index.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), index.location) | |
| 2965 | return | |
| 2966 | fi | |
| 2967 | ||
| 2968 | if need_store then | |
| 2969 | _logger.error(index.location, "indexer [{argument_types[0]}] = {argument_types[1]} not found in {type}") | |
| 2970 | else | |
| 2971 | _logger.error(index.location, "indexer [{argument_types[0]}] not found in {type}") | |
| 2972 | fi | |
| 2973 | ||
| 2974 | index.compile_expressions_state.value = DUMMY(Semantic.Types.ERROR(), index.location) | |
| 2975 | return | |
| 2976 | fi | |
| 2977 | ||
| 2978 | let function = overload_result.function | |
| 2979 | ||
| 2980 | if _resolve_deferred_index(index, function) then | |
| 2981 | _visit_index(index) | |
| 2982 | ||
| 2983 | return | |
| 2984 | fi | |
| 2985 | ||
| 2986 | // Record the indexer-accessor use over the `[...]` | |
| 2987 | // bracket span — from the column after the LHS (the | |
| 2988 | // `[`) to the end of the INDEX expression (the `]`). | |
| 2989 | // find_hover_use prefers shorter matches, so any | |
| 2990 | // inner identifier or variable use nested inside the | |
| 2991 | // brackets still wins on hover; the strict- | |
| 2992 | // containment filter in the semantic-tokens handler | |
| 2993 | // drops this outer span when an inner use is | |
| 2994 | // present, keeping the index expression coloured as | |
| 2995 | // itself. | |
| 2996 | _symbol_use_locations.add_symbol_use( | |
| 2997 | LOCATION( | |
| 2998 | index.left.location.file_name, | |
| 2999 | index.left.location.end_line, | |
| 3000 | index.left.location.end_column + 1, | |
| 3001 | index.location.end_line, | |
| 3002 | index.location.end_column | |
| 3003 | ), function) | |
| 3004 | ||
| 3005 | if function.is_unsafe_constraints then | |
| 3006 | _logger.warn(index.location, "unchecked-constraints", "call to {function} has unchecked constraints") | |
| 3007 | fi | |
| 3008 | ||
| 3009 | if need_store then | |
| 3010 | index.compile_expressions_state.value = | |
| 3011 | TYPE_WRAPPER( | |
| 3012 | function.arguments[1], | |
| 3013 | function.call(index.location, left_value, arguments, null, _function_caller)) | |
| 3014 | else | |
| 3015 | index.compile_expressions_state.value = function.call(index.location, left_value, arguments, null, _function_caller) | |
| 3016 | fi | |
| 3017 | fi | |
| 3018 | si | |
| 3019 | si | |
| 3020 | si |