[PATCH] D42933: [Sema] Avoid -Wformat warning for NSInteger/NSUInteger 'int' values with %zu/%zi long specifiers

[JF Bastien via Phabricator via cfe-commits]

jfb added a comment.
Herald added a reviewer: javed.absar.

I was just looking at this, and I think @arphaman's patch is pretty much the right approach (with 2 suggested fixes below).

I don't think the code we're currently warning on is broken: a user code has `NSInteger` with `%zd` or `NSUInteger` with `%zu`, and on all platforms which support those types the implementor has guaranteed that `(sizeof(size_t) == sizeof(NSInteger)) && (sizeof(ssize_t) == sizeof(NSUInteger))`. I agree that, if we're playing C++ pedant and look at the typedefs, then it's undefined behavior and the code is broken. However the implementation provided more guarantees than C++ does through its platform typedefs so pendantry need not apply (or rather: clang should look no further than the typedef, and trust the platform in this particular case).

We of course should still warn on sign mismatch.

I don't think this should even be a warning with pedantic on: there's no portability issue at all because all OSes and architectures where this could ever fire are guaranteed to do the right thing.

Suggested fixes:

1. Don't compare `CastTyName` directly, instead recurse as `shouldNotPrintDirectly` does so `typedef` nesting is also handled.
2. Add a test that sign mismatched is still diagnosed.

If you all agree I'll post an updated patch.


Repository:
  rC Clang

https://reviews.llvm.org/D42933