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AST: Fix failure to diagnose with redundant same-type constraints #21698

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Merged
merged 1 commit into from
Jan 8, 2019
Merged

AST: Fix failure to diagnose with redundant same-type constraints #21698

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2 changes: 1 addition & 1 deletion lib/AST/GenericSignatureBuilder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6838,7 +6838,7 @@ void GenericSignatureBuilder::checkSameTypeConstraints(
// Put invalid locations after valid ones.
if (locA.isInvalid() || locB.isInvalid()) {
if (locA.isInvalid() != locB.isInvalid())
return locA.isInvalid() ? 1 : -1;
return locA.isValid() ? 1 : -1;

return 0;
}
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11 changes: 11 additions & 0 deletions test/Constraints/same_types.swift
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Expand Up @@ -309,3 +309,14 @@ func testSameTypeCommutativity5<U, T: P1>(_ t: T, _ u: U)
func testSameTypeCommutativity6<U, T: P1>(_ t: T, _ u: U)
where U & P3 == T.Assoc { } // Equivalent to T.Assoc == U & P3
// expected-error@-1 2 {{non-protocol, non-class type 'U' cannot be used within a protocol-constrained type}}

// rdar;//problem/46848889
struct Foo<A: P1, B: P1, C: P1> where A.Assoc == B.Assoc, A.Assoc == C.Assoc {}

struct Bar<A: P1, B: P1> where A.Assoc == B.Assoc {
func f<C: P1>(with other: C) -> Foo<A, B, C> where A.Assoc == C.Assoc {
// expected-note@-1 {{previous same-type constraint 'B.Assoc' == 'C.Assoc' inferred from type here}}
// expected-warning@-2 {{redundant same-type constraint 'A.Assoc' == 'C.Assoc'}}
fatalError()
}
}