averello/swift-mirror
1
0
Fork 0
mirror of https://github.com/apple/swift.git synced 2025-12-21 12:14:44 +01:00
Code Issues Packages Projects Releases Wiki Activity

Fix some LValue type checking issues exposed by key paths.

Browse Source 
We had an inconsistency in the handling of ConstraintKind::Equal in that
we would take
  $T1 Equal $T2
where $T2 was previously bound to a type, and bind the RValue type of
$T2's type to $T1.  That does not allow for us to later attempt to bind
the LValue type of that type to $T1 (as might happen in simplifying an
OptionalObject constraint).

Instead, if $T1 can be bound to an LValue and $T2 is not an LValue,
we'll defer simplifying the Equal constraint until after $T1 is bound
through some other type variable binding or constraint simplification.

Fixes rdar://problem/31724272.
This commit is contained in:
Mark Lacey
2017-05-08 17:28:55 -07:00
parent 03b38534a6
commit 15fb957f09
2 changed files with 36 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

41
lib/Sema/CSSimplify.cpp
View File

@@ -1418,7 +1418,6 @@ ConstraintSystem::matchTypes(Type type1, Type type2, ConstraintKind kind,
}
// Provide a fixed type for the type variable.
bool wantRvalue = kind == ConstraintKind::Equal;
if (typeVar1) {
// Simplify the right-hand type and perform the "occurs" check.
typeVar1 = getRepresentative(typeVar1);
@@ -1426,9 +1425,23 @@ ConstraintSystem::matchTypes(Type type1, Type type2, ConstraintKind kind,
if (typeVarOccursInType(typeVar1, type2))
return formUnsolvedResult();
// If we want an rvalue, get the rvalue.
if (wantRvalue)
type2 = type2->getRValueType();
// Equal constraints allow mixed LValue/RValue bindings.
if (kind == ConstraintKind::Equal) {
// If we could bind an LValue to the type variable, but the
// type that is already bound is not an LValue, defer
// simplifying the constraint since we may come along at a
// later time and attempt to bind the LValue type to this
// type variable.
if (typeVar1->getImpl().canBindToLValue()) {
if (!type2->isLValueType()) {
return formUnsolvedResult();
}
} else {
// If the type variable does not allow LValue bindings,
// get the RValue type.
type2 = type2->getRValueType();
}
}
// If the left-hand type variable cannot bind to an lvalue,
// but we still have an lvalue, fail.
@@ -1467,9 +1480,23 @@ ConstraintSystem::matchTypes(Type type1, Type type2, ConstraintKind kind,
if (typeVarOccursInType(typeVar2, type1))
return formUnsolvedResult();
// If we want an rvalue, get the rvalue.
if (wantRvalue)
type1 = type1->getRValueType();
// Equal constraints allow mixed LValue/RValue bindings.
if (kind == ConstraintKind::Equal) {
// If we could bind an LValue to the type variable, but the
// type that is already bound is not an LValue, defer
// simplifying the constraint since we may come along at a
// later time and attempt to bind the LValue type to this
// type variable.
if (typeVar2->getImpl().canBindToLValue()) {
if (!type1->isLValueType()) {
return formUnsolvedResult();
}
} else {
// If the type variable does not allow LValue bindings,
// get the RValue type.
type1 = type1->getRValueType();
}
}
if (!typeVar2->getImpl().canBindToLValue() &&
type1->isLValueType()) {