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[Constraint solver] Make checked cast constraint generation lazy.

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Fixes rdar://problem/27148148.
This commit is contained in:
Doug Gregor
2016-10-21 16:34:14 -07:00
parent af4d44e013
commit d2cb83b4c7
3 changed files with 38 additions and 18 deletions
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53
lib/Sema/CSSimplify.cpp
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@@ -2144,8 +2144,7 @@ ConstraintSystem::simplifyConstructionConstraint(
Type valueType, FunctionType *fnType, TypeMatchOptions flags,
FunctionRefKind functionRefKind, ConstraintLocator *locator) {
// Desugar the value type.
auto desugarValueType = getFixedTypeRecursive(valueType, true)
->getDesugaredType();
auto desugarValueType = valueType->getDesugaredType();
Type argType = fnType->getInput();
Type resultType = fnType->getResult();
@@ -2370,7 +2369,23 @@ static CheckedCastKind getCheckedCastKind(ConstraintSystem *cs,
ConstraintSystem::SolutionKind
ConstraintSystem::simplifyCheckedCastConstraint(
Type fromType, Type toType,
TypeMatchOptions flags,
ConstraintLocatorBuilder locator) {
TypeMatchOptions subflags = getDefaultDecompositionOptions(flags);
/// Form an unresolved result.
auto formUnsolved = [&] {
if (flags.contains(TMF_GenerateConstraints)) {
addUnsolvedConstraint(
Constraint::create(*this, ConstraintKind::CheckedCast, fromType,
toType, DeclName(), FunctionRefKind::Compound,
getConstraintLocator(locator)));
return SolutionKind::Solved;
}
return SolutionKind::Unsolved;
};
do {
// Dig out the fixed type to which this type refers.
fromType = getFixedTypeRecursive(fromType, /*wantRValue=*/true);
@@ -2378,7 +2393,7 @@ ConstraintSystem::simplifyCheckedCastConstraint(
// If we hit a type variable without a fixed type, we can't
// solve this yet.
if (fromType->isTypeVariableOrMember())
return SolutionKind::Unsolved;
return formUnsolved();
// Dig out the fixed type to which this type refers.
toType = getFixedTypeRecursive(toType, /*wantRValue=*/true);
@@ -2386,7 +2401,7 @@ ConstraintSystem::simplifyCheckedCastConstraint(
// If we hit a type variable without a fixed type, we can't
// solve this yet.
if (toType->isTypeVariableOrMember())
return SolutionKind::Unsolved;
return formUnsolved();
Type origFromType = fromType;
Type origToType = toType;
@@ -2414,6 +2429,9 @@ ConstraintSystem::simplifyCheckedCastConstraint(
}
}
// We've decomposed the types further, so adopt the subflags.
flags = subflags;
// If nothing changed, we're done.
if (fromType.getPointer() == origFromType.getPointer() &&
toType.getPointer() == origToType.getPointer())
@@ -2435,14 +2453,12 @@ ConstraintSystem::simplifyCheckedCastConstraint(
toBaseType)) {
// The class we're bridging through must be a subtype of the type we're
// coming from.
addConstraint(ConstraintKind::Subtype, classType, fromBaseType,
getConstraintLocator(locator));
return SolutionKind::Solved;
return matchTypes(classType, fromBaseType, TypeMatchKind::Subtype,
subflags, locator);
}
addConstraint(ConstraintKind::Subtype, toBaseType, fromBaseType,
getConstraintLocator(locator));
return SolutionKind::Solved;
return matchTypes(toBaseType, fromBaseType, TypeMatchKind::Subtype,
subflags, locator);
}
case CheckedCastKind::DictionaryDowncast: {
Type fromKeyType, fromValueType;
@@ -2462,8 +2478,7 @@ ConstraintSystem::simplifyCheckedCastConstraint(
}
// Perform subtype check on the possibly-bridged-through key type.
TypeMatchOptions subflags = TMF_GenerateConstraints;
auto result = matchTypes(toKeyType, fromKeyType, TypeMatchKind::Subtype,
auto result = matchTypes(toKeyType, fromKeyType, TypeMatchKind::Subtype,
subflags, locator);
if (result == SolutionKind::Error)
return result;
@@ -2482,7 +2497,7 @@ ConstraintSystem::simplifyCheckedCastConstraint(
return result;
case SolutionKind::Unsolved:
return SolutionKind::Unsolved;
return SolutionKind::Solved;
case SolutionKind::Error:
return SolutionKind::Error;
@@ -2501,13 +2516,13 @@ ConstraintSystem::simplifyCheckedCastConstraint(
toBaseType)) {
// The class we're bridging through must be a subtype of the type we're
// coming from.
addConstraint(ConstraintKind::Subtype, classType, fromBaseType,
getConstraintLocator(locator));
addConstraint(ConstraintKind::Subtype, classType,
fromBaseType, locator);
return SolutionKind::Solved;
}
addConstraint(ConstraintKind::Subtype, toBaseType, fromBaseType,
getConstraintLocator(locator));
addConstraint(ConstraintKind::Subtype, toBaseType,
fromBaseType, locator);
return SolutionKind::Solved;
}
@@ -4144,6 +4159,9 @@ ConstraintSystem::addConstraintImpl(ConstraintKind kind, Type first,
return simplifyConformsToConstraint(first, second, kind, locator,
subflags);
case ConstraintKind::CheckedCast:
return simplifyCheckedCastConstraint(first, second, subflags, locator);
case ConstraintKind::Bind: // FIXME: This should go through matchTypes() above
default: {
@@ -4254,6 +4272,7 @@ ConstraintSystem::simplifyConstraint(const Constraint &constraint) {
case ConstraintKind::CheckedCast: {
auto result = simplifyCheckedCastConstraint(constraint.getFirstType(),
constraint.getSecondType(),
None,
constraint.getLocator());
// NOTE: simplifyCheckedCastConstraint() may return Unsolved, e.g. if the
// subexpression's type is unresolved. Don't record the fix until we