[all-commits] [llvm/llvm-project] d72e71: [NFC] [CMake] Add -Wno-dangling-else for GCC built...

[Jinsong Ji via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: d72e711e864dad7e3a434d66f3febad2b1596335
      https://github.com/llvm/llvm-project/commit/d72e711e864dad7e3a434d66f3febad2b1596335
  Author: Jinsong Ji <jinsong.ji at intel.com>
  Date:   2024-10-26 (Sat, 26 Oct 2024)

  Changed paths:
    M llvm/unittests/CMakeLists.txt

  Log Message:
  -----------
  [NFC] [CMake] Add -Wno-dangling-else for GCC built unittests  (#112817)

This is one of the many PRs to fix errors with LLVM_ENABLE_WERROR=on.
Built by GCC 11.

Fix warnings:

llvm/unittests/ProfileData/CoverageMappingTest.cpp: In member function
‘virtual void
{anonymous}::CoverageMappingTest_TVIdxBuilder_Test::TestBody()’:
llvm/unittests/ProfileData/CoverageMappingTest.cpp:1116:10: error:
suggest explicit braces to avoid ambiguous ‘else’
[-Werror=dangling-else]
 1116 |       if (Node.NextIDs[C] < 0)

The problem here is because these macros, eg: EXPECT_TRUE are expanded
to a single line multi-statement code with if/else, which is indeed
ambiguous after pre-processing. a simple example would be like:
https://godbolt.org/z/4zjn56qrP

    if(x)
     switch (0) case 0: default: if (...) ; else return;;

Given that omit braces in such cases is part of LLVM's style guide, and
it is hard to add braces in gtest just for GCC's warning, add
-Wno-dangling-else for GCC instead.



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