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[Type checker] Allow bridging conversions to more-optional types.

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The prior formulation of bridging conversions allowed conversion to
more-optional types, e.g., converting an "NSDate" to "Date?", which
was broken by my recent refactoring in this area. Allow bridging
conversions to more-optional types by introducing extra optional
injections at the end.

Fixes rdar://problem/29780527.
This commit is contained in:
Doug Gregor
2016-12-22 10:02:41 -08:00
parent 2fffbb1365
commit f7b5d9d69e
5 changed files with 67 additions and 17 deletions
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25
lib/Sema/CSSimplify.cpp
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@@ -3328,10 +3328,19 @@ ConstraintSystem::simplifyBridgingConstraint(Type type1,
return SolutionKind::Error;
}
// Local function to count the optional injections that will be performed
// after the bridging conversion.
auto countOptionalInjections = [&] {
if (numToOptionals > numFromOptionals)
increaseScore(SK_ValueToOptional, numToOptionals - numFromOptionals);
};
// Anything can be explicitly converted to AnyObject using the universal
// bridging conversion. We allow this so long as we have at least as many
// optionals in the source as in the destination.
if (unwrappedToType->isAnyObject() && numFromOptionals >= numToOptionals) {
// bridging conversion. This allows both extraneous optionals in the source
// (because optionals themselves can be boxed for AnyObject) and in the
// destination (we'll perform the extra injections at the end).
if (unwrappedToType->isAnyObject()) {
countOptionalInjections();
return SolutionKind::Solved;
}
@@ -3346,8 +3355,9 @@ ConstraintSystem::simplifyBridgingConstraint(Type type1,
}
}
// # of optionals must match for bridging conversions.
if (numToOptionals != numFromOptionals) {
// The source cannot be more optional than the destination, because bridging
// conversions don't allow us to implicitly check for a value in the optional.
if (numFromOptionals > numToOptionals) {
return SolutionKind::Error;
}
@@ -3357,6 +3367,7 @@ ConstraintSystem::simplifyBridgingConstraint(Type type1,
!= TC.Context.getImplicitlyUnwrappedOptionalDecl() &&
!flags.contains(TMF_ApplyingOperatorParameter) &&
unwrappedToType->isBridgeableObjectType()) {
countOptionalInjections();
if (Type classType = TC.Context.getBridgedToObjC(DC, unwrappedFromType)) {
return matchTypes(classType, unwrappedToType, ConstraintKind::Subtype, subflags,
locator);
@@ -3427,6 +3438,7 @@ ConstraintSystem::simplifyBridgingConstraint(Type type1,
== ConstraintSystem::SolutionKind::Error)
return SolutionKind::Error;
countOptionalInjections();
return matchTypes(unwrappedFromType, objcClass, ConstraintKind::Subtype,
subflags, locator);
}
@@ -3435,6 +3447,7 @@ ConstraintSystem::simplifyBridgingConstraint(Type type1,
// Bridging the elements of an array.
if (auto fromElement = isArrayType(unwrappedFromType)) {
if (auto toElement = isArrayType(unwrappedToType)) {
countOptionalInjections();
return simplifyBridgingConstraint(
*fromElement, *toElement, subflags,
locator.withPathElement(
@@ -3453,6 +3466,7 @@ ConstraintSystem::simplifyBridgingConstraint(Type type1,
/*allowFixes=*/false,
locator.withPathElement(
LocatorPathElt::getGenericArgument(0)));
countOptionalInjections();
return SolutionKind::Solved;
}
}
@@ -3460,6 +3474,7 @@ ConstraintSystem::simplifyBridgingConstraint(Type type1,
// Bridging the elements of a set.
if (auto fromElement = isSetType(unwrappedFromType)) {
if (auto toElement = isSetType(unwrappedToType)) {
countOptionalInjections();
return simplifyBridgingConstraint(
*fromElement, *toElement, subflags,
locator.withPathElement(