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Reconcile function default values between decl and def (#7665)

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Updates the pattern matching code to support unspecified default values.
Adds logic to decl and def merge code to diagnose mismatches in defaults
if specified in both places, or if let entirely unspecified.

Per https://github.com/carbon-language/carbon-lang/pull/7521.
This commit is contained in:
Lucile Rose Nihlen
2026-09-08 20:41:58 +00:00
committed by GitHub
parent 5a07a14fe9
commit ca9e985fa8
30 changed files with 4624 additions and 3875 deletions
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toolchain/check/handle_function.cpp
+41 -38
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@@ -518,6 +518,7 @@ static auto CheckUnusedBindingsInPattern(Context& context,
SemIR::InstId pattern_id) -> void {
llvm::SmallVector<SemIR::InstId> work_list;
work_list.push_back(pattern_id);
while (!work_list.empty()) {
auto current_id = work_list.pop_back_val();
auto inst = context.insts().Get(current_id);
@@ -611,7 +612,7 @@ static auto DiagnoseOutOfOrderDefaults(Context& context,
// True if the current pattern being processed has a default value
// specified.
bool pattern_has_default = false;
bool current_pattern_has_default = false;
// The current pattern we are processing, stored separately since it's been
// popped from the `pattern_work_list` and already processed, just may need
@@ -622,38 +623,40 @@ static auto DiagnoseOutOfOrderDefaults(Context& context,
llvm::SmallVector<SemIR::InstId> pattern_work_list;
// A list of subpatterns missing required defaults, to coalesce error
// reporting into a single diagnostic and limit diagnostic spam.
// reporting into a single diagnostic.
llvm::SmallVector<SemIR::InstId> patterns_missing_defaults;
};
llvm::SmallVector<PatternLevelState> level_state_stack;
level_state_stack.push_back({});
for (auto subpattern_id :
llvm::reverse(context.inst_blocks().Get(function.param_patterns_id))) {
level_state_stack.back().subpattern_ids.push_back(subpattern_id);
}
llvm::append_range(
level_state_stack.back().subpattern_ids,
llvm::reverse(context.inst_blocks().Get(function.param_patterns_id)));
while (!level_state_stack.empty()) {
auto& state = level_state_stack.back();
while (!state.subpattern_ids.empty() || !state.pattern_work_list.empty() ||
state.current_id.has_value()) {
if (!state.current_id.has_value()) {
state.pattern_work_list.push_back(state.subpattern_ids.pop_back_val());
state.pattern_has_default = false;
PatternLevelState* state = &level_state_stack.back();
while (!state->subpattern_ids.empty() ||
!state->pattern_work_list.empty() || state->current_id.has_value()) {
// If we're not resuming processing a pattern from a nested state, start
// processing the next subpattern.
if (!state->current_id.has_value()) {
state->pattern_work_list.push_back(
state->subpattern_ids.pop_back_val());
state->current_pattern_has_default = false;
}
while (!state.pattern_work_list.empty()) {
state.current_id = state.pattern_work_list.pop_back_val();
auto inst = context.insts().Get(state.current_id);
while (!state->pattern_work_list.empty()) {
state->current_id = state->pattern_work_list.pop_back_val();
auto inst = context.insts().Get(state->current_id);
CARBON_KIND_SWITCH(inst) {
case CARBON_KIND(SemIR::DefaultValuePattern default_value_pattern): {
state.pattern_has_default = true;
state.pattern_work_list.push_back(
state->current_pattern_has_default = true;
state->pattern_work_list.push_back(
default_value_pattern.subpattern_id);
break;
}
case CARBON_KIND(
SemIR::WrapperBindingPattern wrapper_binding_pattern): {
state.pattern_work_list.push_back(
state->pattern_work_list.push_back(
wrapper_binding_pattern.subpattern_id);
break;
}
@@ -663,30 +666,31 @@ static auto DiagnoseOutOfOrderDefaults(Context& context,
if (!elements.empty()) {
// Start a new state for the nested tuple pattern elements.
level_state_stack.push_back({});
state = level_state_stack.back();
for (auto element_id : llvm::reverse(elements)) {
state.subpattern_ids.push_back(element_id);
}
state = &level_state_stack.back();
llvm::append_range(state->subpattern_ids,
llvm::reverse(elements));
}
break;
}
default:
// We only process patterns containing subpatterns, so this is an
// intentional no-op.
break;
}
}
// Finished processing this subpattern, detect a missing default if
// required.
if (state.pattern_has_default &&
!state.first_pattern_with_default.has_value()) {
state.first_pattern_with_default = state.current_id;
} else if (!state.pattern_has_default &&
state.first_pattern_with_default.has_value()) {
state.patterns_missing_defaults.push_back(state.current_id);
if (state->current_pattern_has_default &&
!state->first_pattern_with_default.has_value()) {
state->first_pattern_with_default = state->current_id;
} else if (!state->current_pattern_has_default &&
state->first_pattern_with_default.has_value()) {
state->patterns_missing_defaults.push_back(state->current_id);
}
state.current_id = SemIR::InstId::None;
state->current_id = SemIR::InstId::None;
}
// Finished processing this tuple-pattern, emit diagnostics if any.
if (!state.patterns_missing_defaults.empty()) {
if (!state->patterns_missing_defaults.empty()) {
CARBON_DIAGNOSTIC(RequiredPatternDefaultValueMissing, Error,
"this pattern is missing a required default value.");
CARBON_DIAGNOSTIC(RequiredPatternDefaultValueFirstDefault, Note,
@@ -695,16 +699,15 @@ static auto DiagnoseOutOfOrderDefaults(Context& context,
CARBON_DIAGNOSTIC(
RequiredPatternDefaultValueMissingAdditional, Note,
"this pattern is also missing a required default value.");
auto inst_ref =
llvm::ArrayRef<SemIR::InstId>(state.patterns_missing_defaults);
auto diag = context.emitter().Build(inst_ref.consume_front(),
RequiredPatternDefaultValueMissing);
diag.Note(state.first_pattern_with_default,
RequiredPatternDefaultValueFirstDefault);
auto inst_ref = llvm::ArrayRef(state->patterns_missing_defaults);
auto builder = context.emitter().Build(
inst_ref.consume_front(), RequiredPatternDefaultValueMissing);
for (auto inst_id : inst_ref) {
diag.Note(inst_id, RequiredPatternDefaultValueMissingAdditional);
builder.Note(inst_id, RequiredPatternDefaultValueMissingAdditional);
}
diag.Emit();
builder.Note(state->first_pattern_with_default,
RequiredPatternDefaultValueFirstDefault);
builder.Emit();
}
level_state_stack.pop_back();
}