SILGen: Lower formal callee type pre-opaque-type-substitution. #33276
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Prior to this fix, if we called a generic function with a substitutable opaque type as its formal substitution,
as in:
```
func opaque() -> some Any { return { } as ()->() }
func generic<T>(_ x: T) -> T { return x }
let x = generic(opaque())
```
then we would generate the formal type of the callee using the substitutions *after* opaque type expansion,
causing us to emit functions and metatypes at the wrong abstraction level and crash with SIL-level type mismatches.
Fixes rdar://problem/65683913.
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@swift-ci Please test |
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@swift-ci Please test source compatibility |
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Compatibility suite failures look like server configuration issues unrelated to this change. |
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@swift-ci Please nominate |
tkremenek
approved these changes
Aug 4, 2020
AnthonyLatsis
added
swift 5.3
🍒 release cherry pick
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Explanation: Fixes a regression in handling generic functions that are called with opaque types as their generic arguments, which would cause functions generically returning functions or metatypes to crash or potentially miscompile.
Scope: Regression from Swift 5.2
Risk: Low.
Testing: Swift CI, compatibility suite
Reviewed by: @aschwaighofer