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Remove caching of return slot usage. (#4163)

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The caching isn't buying us much, and is adding complexity and
divergence between the codepaths for generic and non-generic functions.

This means we no longer suppress diagnostics for the second or
subsequent time we call a function with an incomplete return type. If we
want to add that back, it might be worth considering moving the
suppression to `TryToCompleteType` and only diagnosing that a type is
incomplete once, regardless of why we're requiring it to be complete.
This commit is contained in:
Richard Smith
2024-07-25 20:29:59 +00:00
committed by GitHub
parent bf1106fc34
commit a9e835f3dc
14 changed files with 183 additions and 192 deletions
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toolchain/check/function.cpp
+21 -41
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@@ -73,49 +73,29 @@ auto CheckFunctionTypeMatches(Context& context,
auto CheckFunctionReturnType(Context& context, SemIRLoc loc,
SemIR::Function& function,
SemIR::SpecificId specific_id)
-> SemIR::Function::ReturnSlot {
// If we have already checked the return type, we have nothing to do.
if (function.return_slot != SemIR::Function::ReturnSlot::NotComputed &&
!specific_id.is_valid()) {
return function.return_slot;
-> SemIR::ReturnInfo {
auto return_info = function.GetReturnInfo(context.sem_ir(), specific_id);
// If we couldn't determine the return information due to the return type
// being incomplete, try to complete it now.
if (return_info.return_slot == SemIR::ReturnSlot::Incomplete) {
auto diagnose_incomplete_return_type = [&] {
CARBON_DIAGNOSTIC(IncompleteTypeInFunctionReturnType, Error,
"Function returns incomplete type `{0}`.",
SemIR::TypeId);
return context.emitter().Build(loc, IncompleteTypeInFunctionReturnType,
return_info.type_id);
};
// TODO: Consider suppressing the diagnostic if we've already diagnosed a
// definition or call to this function.
if (context.TryToCompleteType(return_info.type_id,
diagnose_incomplete_return_type)) {
return_info = function.GetReturnInfo(context.sem_ir(), specific_id);
}
}
if (!function.return_storage_id.is_valid()) {
// Implicit `-> ()` has no return slot.
function.return_slot = SemIR::Function::ReturnSlot::Absent;
return function.return_slot;
}
auto return_type_id =
function.GetDeclaredReturnType(context.sem_ir(), specific_id);
CARBON_CHECK(return_type_id.is_valid())
<< "Have return storage but no return type.";
// Check the return type is complete. Only diagnose incompleteness if we've
// not already done so.
auto diagnose_incomplete_return_type = [&] {
CARBON_DIAGNOSTIC(IncompleteTypeInFunctionReturnType, Error,
"Function returns incomplete type `{0}`.", SemIR::TypeId);
return context.emitter().Build(loc, IncompleteTypeInFunctionReturnType,
return_type_id);
};
SemIR::Function::ReturnSlot result;
if (!context.TryToCompleteType(
return_type_id,
function.return_slot == SemIR::Function::ReturnSlot::Error
? std::nullopt
: std::optional(diagnose_incomplete_return_type))) {
result = SemIR::Function::ReturnSlot::Error;
} else if (SemIR::GetInitRepr(context.sem_ir(), return_type_id)
.has_return_slot()) {
result = SemIR::Function::ReturnSlot::Present;
} else {
result = SemIR::Function::ReturnSlot::Absent;
}
if (!specific_id.is_valid()) {
function.return_slot = result;
}
return result;
return return_info;
}
} // namespace Carbon::Check