[6.2.2] Disfavor overloads of __checkFunctionCall() with variadic generics.
#1406
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…#1389) This works around rdar://122011759 which appears to have been exacerbated by swiftlang/swift#84907. For example: ```swift let file = try #require(fmemopen(nil, 1, "wb+")) ``` The third parameter of `fmemopen()` is of type `const char *` (AKA `UnsafePointer<CChar>`) and we're passing the string literal `"wb+"` which is implicitly cast to a C string by the compiler. However, overload resolution of the expansion function used by `#require()` is now preferring an overload that uses variadic generics, and that overload is impacted by a compiler issue (rdar://122011759) that causes it to pass a garbage pointer as the temporary C string. Previously, the type checker would pick an overload with a concrete, finite set of generic arguments (`<T, Arg0, Arg1, Arg2, R>` instead of `<T, each U, R>`.) ### Checklist: - [x] Code and documentation should follow the style of the [Style Guide](https://github.com/apple/swift-testing/blob/main/Documentation/StyleGuide.md). - [x] If public symbols are renamed or modified, DocC references should be updated.
grynspan
requested review from
briancroom,
stmontgomery and
suzannaratcliff
as code owners
grynspan
added
workaround
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@swift-ci test |
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Looks good, but unrelatedly, I just noticed we do not yet have CI coverage for the |
stmontgomery
approved these changes
Nov 7, 2025
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@_disfavoredOverloadso that the__check()function we use during expansion of#expect()for function call expressions is preferentially the one with hard-coded arguments rather than variadic generics (which suffer from a bug that's fixed in 6.3.)#expect()macro expansion__checkFunctionCall()with variadic generics. #1389