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Merge pull request #64192 from xedin/rdar-106364495

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[CSSimplify] Propagate contextual result type into result builder tra…
This commit is contained in:
Holly Borla
2023-03-08 09:53:38 -08:00
committed by GitHub
parent 56f8e5484b 3ff03469e7
commit df755d4f90
2 changed files with 41 additions and 4 deletions
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26
lib/Sema/CSSimplify.cpp
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@@ -3532,11 +3532,29 @@ ConstraintSystem::matchFunctionTypes(FunctionType *func1, FunctionType *func2,
}
}
auto resultMatchKind = subKind;
// Performance optimization: Propagate fully or partially resolved contextual
// type down into the body of result builder transformed closure by eagerly
// binding intermediate body result type to the contextual one. This helps to
// determine when closure body could be solved early.
//
// TODO: This could be extended to cover all multi-statement closures.
//
// See \c BindingSet::favoredOverConjunction for more details.
if (resultMatchKind >= ConstraintKind::Subtype &&
!func2->getResult()->isTypeVariableOrMember()) {
if (auto *closure = getAsExpr<ClosureExpr>(locator.trySimplifyToExpr())) {
if (!closure->hasExplicitResultType() &&
getAppliedResultBuilderTransform(closure)) {
resultMatchKind = ConstraintKind::Equal;
}
}
}
// Result type can be covariant (or equal).
return matchTypes(func1->getResult(), func2->getResult(), subKind,
subflags,
locator.withPathElement(
ConstraintLocator::FunctionResult));
return matchTypes(func1->getResult(), func2->getResult(), resultMatchKind,
subflags,
locator.withPathElement(ConstraintLocator::FunctionResult));
}
ConstraintSystem::TypeMatchResult