[PATCH] D95396: Improve static_assert/_Static_assert diagnostics

[Richard Smith - zygoloid via Phabricator via cfe-commits]

rsmith added inline comments.


================
Comment at: clang/lib/Parse/ParseDeclCXX.cpp:874-876
+    if (!getLangOpts().CPlusPlus)
+      Diag(Tok, diag::warn_cxx_static_assert_in_c)
+          << FixItHint::CreateReplacement(Tok.getLocation(), "_Static_assert");
----------------
I don't think this diagnostic is useful as-is: on Windows, including `<assert.h>` doesn't help because it doesn't `#define static_assert`. And people hitting this also can't switch to using `_Static_assert`, because MSVC doesn't provide it, only `static_assert`.

If we want to warn here, we could perhaps check whether `<assert.h>` has been included, but getting that check correct across PCH / modules is not straightforward. (If we knew what include guard the CRT's `assert.h` used (if any), I guess we could check whether that's defined, but that'd be a bit of a hack.) But I'm somewhat inclined to think we don't have a good way to distinguish between the good cases and the bad ones, so we shouldn't warn. Hopefully MS will fix their CRT at some point and we can stop providing this compatibility hack entirely (or start warning on it by default).


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D95396/new/

https://reviews.llvm.org/D95396