Sema: don't consider opaque types distinct for overloading purposes. #24166
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slavapestov
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Apr 19, 2019
lib/AST/Decl.cpp
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| // Replace an opaque archetype with a common dummy type. Functions and | ||
| // subscripts cannot overload differing only in opaque return types. | ||
| if (type->getAs<OpaqueTypeArchetypeType>()) { | ||
| type = BuiltinIntegerType::get(0x12345678u, ctx); |
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Would erasing to the existential type be better? I'm worried this might leak through in diagnostics
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Maybe. That would mean that you couldn't overload:
func foo() -> any P
func foo() -> some P
I was also trying to prevent:
func foo() -> some P
func foo() -> some Q
since there would still be no way to disambiguate these.
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Couldn’t the latter be disambiguated by calling a generic function with a T: P or T: Q constraint with foo() as an argument?
IIRC the redeclaration checking uses a tuple of flags in addition to the erased overload type as the unique key. You could add a HasOpaqueResult flag and erase to an existential.
This is necessary because: ``` func foo() -> some P func foo() -> some P ``` theoretically defines two distinct return types, but there'd be no way to disambiguate them. Disallow overloading only by opaque return type.
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This is necessary because:
theoretically defines two distinct return types, but there'd be no way to disambiguate them. Disallow overloading only by opaque return type.