[PATCH] D122976: Bump minimum toolchain version

[James Y Knight via Phabricator via llvm-commits]

jyknight accepted this revision.
jyknight added a comment.

LG, just some minor comments.



================
Comment at: llvm/cmake/modules/CheckCompilerVersion.cmake:100-101
     endif()
     # Test for libstdc++ version of at least 5.1 by checking for std::iostream_category().
     # Note: We should check _GLIBCXX_RELEASE when possible (i.e., for GCC 7.1 and up).
     check_cxx_source_compiles("
----------------
jyknight wrote:
> As this change increments the minimum GCC version to 7, we should switch to using `_GLIBCXX_RELEASE` to check the libstdc++ version. This is better than using `__GLIBCXX__` dates, because the dates are updated for every patch release on every branch, so it cannot actually distinguish between branches properly.
> 
> The hack of checking iostream_category can go away, as well (it was just a workaround for the unreliability of GLIBCXX).
> 
> So, the whole check below should be able to be simplified to:
> ```
> #if defined(__GLIBCXX__)
> #if !defined(_GLIBCXX_RELEASE) || _GLIBCXX_RELEASE < ${LIBSTDCXX_SOFT_ERROR}
> #error Unsupported libstdc++ version
> #endif
> #endif
> int main() { return 0; }
> ```
> 
Delete the comment; it's now incorrect, and no longer necessary since the test is now obvious.
Delete unnecessary `#include <iosfwd>`.



Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D122976/new/

https://reviews.llvm.org/D122976