[PATCH] D17444: PR26672: [MSVC] Clang does not recognize "static_assert" keyword in C mode

[Reid Kleckner via Phabricator via cfe-commits]

rnk added a subscriber: STL_MSFT.
rnk added a comment.

I chatted with @rsmith offline and the solution we came up with was to do both of the following:

- make static_assert a keyword under -fms-compatibility (it is a technically non-conforming extension)
- ask @STL_MSFT if `#define static_assert _Static_assert` can be added to the VC assert.h header. This has the benefit of fixing the issue for users with a new VC and an old clang.
- when a fixed assert.h is released, remove this nonconforming keyword from clang, or make it conditional on a new enough _MSC_VER

However, local testing has shown that Visual C++ doesn't recognize _Static_assert, so the second part of this isn't so simple. The problem is that we want users to be able to compile the following conforming C11 code with -fno-ms-compatibility:

  #include <assert.h>
  static_assert(true, "foo");

The other solution is to have VC assert.h say:

  #ifdef __clang__
  #define static_assert _Static_assert
  #endif

... but maybe it would be better to teach the Visual C++ compiler to recognize the C11 _Static_assert keyword in the first place.


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