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Comment the restricted conversions with their formal

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reduction rules.

Swift SVN r14795
This commit is contained in:
John McCall
2014-03-07 21:57:35 +00:00
parent 8d9666f518
commit 3c1b765fa8
1 changed files with 16 additions and 0 deletions
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16
lib/Sema/CSSimplify.cpp
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@@ -1802,16 +1802,21 @@ ConstraintSystem::simplifyRestrictedConstraint(ConversionRestrictionKind restric
unsigned flags,
ConstraintLocatorBuilder locator) {
switch (restriction) {
// for $< in { <, <c, <oc }:
// T_i $< U_i ===> (T_i...) $< (U_i...)
case ConversionRestrictionKind::TupleToTuple:
return matchTupleTypes(type1->castTo<TupleType>(),
type2->castTo<TupleType>(),
matchKind, flags, locator);
// T <c U ===> T <c (U)
case ConversionRestrictionKind::ScalarToTuple:
return matchScalarToTupleTypes(type1,
type2->castTo<TupleType>(),
matchKind, flags, locator);
// for $< in { <, <c, <oc }:
// T $< U ===> (T) $< U
case ConversionRestrictionKind::TupleToScalar:
return matchTupleToScalarTypes(type1->castTo<TupleType>(),
type2,
@@ -1827,19 +1832,29 @@ ConstraintSystem::simplifyRestrictedConstraint(ConversionRestrictionKind restric
return matchTypes(type1->getRValueType(), type2,
matchKind, flags, locator);
// for $< in { <, <c, <oc }:
// T $< U, U : P_i ===> T $< protocol<P_i...>
case ConversionRestrictionKind::Existential:
return matchExistentialTypes(type1, type2,
matchKind, flags, locator);
// for $< in { <, <c, <oc }:
// T $< U ===> T $< U?
case ConversionRestrictionKind::ValueToOptional: {
assert(matchKind >= TypeMatchKind::Subtype);
auto generic2 = type2->castTo<BoundGenericType>();
assert(generic2->getDecl()->classifyAsOptionalType());
return matchTypes(type1, generic2->getGenericArgs()[0],
matchKind, flags, locator);
}
// for $< in { <, <c, <oc }:
// T $< U ===> T? $< U?
// T $< U ===> @unchecked T? $< @unchecked U?
// T $< U ===> @unchecked T? $< U?
case ConversionRestrictionKind::UncheckedOptionalToOptional:
case ConversionRestrictionKind::OptionalToOptional: {
assert(matchKind >= TypeMatchKind::Subtype);
auto generic1 = type1->castTo<BoundGenericType>();
auto generic2 = type2->castTo<BoundGenericType>();
assert(generic1->getDecl()->classifyAsOptionalType());
@@ -1849,6 +1864,7 @@ ConstraintSystem::simplifyRestrictedConstraint(ConversionRestrictionKind restric
matchKind, flags, locator);
}
// T' < U, hasMember(T, conversion, T -> T') ===> T <c U
case ConversionRestrictionKind::User:
assert(matchKind >= TypeMatchKind::Conversion);
return tryUserConversion(*this, type1,