[libc][complex] Silence pedantic warning

[Sh0g0-1758]

Fix buildbot errors due to #111659

[Sh0g0-1758]

@lntue

[llvmbot]

@llvm/pr-subscribers-libc

Author: Shourya Goel (Sh0g0-1758)

Changes

Fix buildbot errors due to #111659

---

Full diff: https://github.com/llvm/llvm-project/pull/112239.diff

1 Files Affected:

• (modified) libc/cmake/modules/LLVMLibCCompileOptionRules.cmake (+2)

diff --git a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
index 7af67e629471cb..e3a111c62cdb71 100644
--- a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
+++ b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
@@ -154,6 +154,7 @@ function(_get_common_compile_options output_var flags)
     list(APPEND compile_options "-Wno-sign-conversion")
     # Silence this warning because _Complex is a part of C99.
     list(APPEND compile_options "-Wno-c99-extensions")
+    list(APPEND compile_options "-Wno-pedantic")
     list(APPEND compile_options "-Wimplicit-fallthrough")
     list(APPEND compile_options "-Wwrite-strings")
     list(APPEND compile_options "-Wextra-semi")
@@ -231,6 +232,7 @@ function(_get_common_test_compile_options output_var c_test flags)
     # list(APPEND compile_options "-Wextra-semi")
     # Silence this warning because _Complex is a part of C99.
     list(APPEND compile_options "-Wno-c99-extensions")
+    list(APPEND compile_options "-Wno-pedantic")
     # if(NOT CMAKE_COMPILER_IS_GNUCXX)
     #   list(APPEND compile_options "-Wnewline-eof")
     #   list(APPEND compile_options "-Wnonportable-system-include-path")

[jhuber6]

Not sure we want to just silence all of these warnings, the issue seems to be redeclaration of some complex types, we could probably just use the compiler ones.

[lntue]

Not sure we want to just silence all of these warnings, the issue seems to be redeclaration of some complex types, we could probably just use the compiler ones.

So this is the issue: https://godbolt.org/z/zs5Px5Tco
And for some reason, adding Wno-c99-extensions there still not suppresses _Complex warnings.

[nickdesaulniers]

And for some reason, adding Wno-c99-extensions there still not suppresses _Complex warnings.

Yes it does: https://godbolt.org/z/aacj54rdM -Wno-* needs to occur AFTER -Wpedantic. The way these work in Clang (and GCC which Clang matches its behavior from (AFAIK)) is that the last occurrence of these on the command line "wins." -Wpedantic is a "group" that enables a bunch of warnings implicitly, so then after you'd need to re-disable the flags you want.

-Wpedatic to me means we're sticking with strict ISO C (or C++). If we use extensions (that are supported by the two compilers we support), then -Wpedantic doesn't add much value IMO.