[all-commits] [llvm/llvm-project] e8e0c0: Merging r371557:

[Richard Smith via All-commits]

  Branch: refs/heads/release/9.x
  Home:   https://github.com/llvm/llvm-project
  Commit: e8e0c077c416a15ccdec53c1252b787f6649ae70
      https://github.com/llvm/llvm-project/commit/e8e0c077c416a15ccdec53c1252b787f6649ae70
  Author: Richard Smith <richard-llvm at metafoo.co.uk>
  Date:   2019-12-11 (Wed, 11 Dec 2019)

  Changed paths:
    M clang/lib/AST/ExprConstant.cpp
    M clang/test/Sema/i-c-e.c

  Log Message:
  -----------
  Merging r371557:

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r371557 | rsmith | 2019-09-10 14:24:09 -0700 (Tue, 10 Sep 2019) | 7 lines

When evaluating a __builtin_constant_p conditional, always enter
constant-folding mode regardless of the original evaluation mode.

In order for this to be correct, we need to track whether we're checking
for a potential constant expression or checking for undefined behavior
separately from the evaluation mode enum, since we don't want to clobber
those states when entering constant-folding mode.
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