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Merge pull request #38199 from xedin/rdar-65667992

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[ConstraintSystem] Bind missing member in pattern match to a hole early
This commit is contained in:
Pavel Yaskevich
2021-07-02 12:40:13 -07:00
committed by GitHub
parent e41656d2ea c1d0036b09
commit 6aa0ea552a
2 changed files with 50 additions and 4 deletions
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25
lib/Sema/CSSimplify.cpp
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@@ -4887,14 +4887,24 @@ bool ConstraintSystem::repairFailures(
}
case ConstraintLocator::PatternMatch: {
auto *pattern = elt.castTo<LocatorPathElt::PatternMatch>().getPattern();
bool isMemberMatch =
lhs->is<FunctionType>() && isa<EnumElementPattern>(pattern);
// If member reference couldn't be resolved, let's allow pattern
// to have holes.
if (rhs->isPlaceholder() && isMemberMatch) {
recordAnyTypeVarAsPotentialHole(lhs);
return true;
}
// If either type is a placeholder, consider this fixed.
if (lhs->isPlaceholder() || rhs->isPlaceholder())
return true;
// If the left-hand side is a function type and the pattern is an enum
// element pattern, call it a contextual mismatch.
auto pattern = elt.castTo<LocatorPathElt::PatternMatch>().getPattern();
if (lhs->is<FunctionType>() && isa<EnumElementPattern>(pattern)) {
// If member reference didn't match expected pattern,
// let's consider that a contextual mismatch.
if (isMemberMatch) {
recordAnyTypeVarAsPotentialHole(lhs);
recordAnyTypeVarAsPotentialHole(rhs);
@@ -8207,6 +8217,13 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyMemberConstraint(
// `key path` constraint can't be retired until all components
// are simplified.
addTypeVariableConstraintsToWorkList(memberTypeVar);
} else if (locator->isLastElement<LocatorPathElt::PatternMatch>()) {
// Let's handle member patterns specifically because they use
// equality instead of argument application constraint, so allowing
// them to bind member could mean missing valid hole positions in
// the pattern.
assignFixedType(memberTypeVar,
PlaceholderType::get(getASTContext(), memberTypeVar));
} else {
recordPotentialHole(memberTypeVar);
}