[PATCH] D75056: [Driver] Default to -fno-common for all targets

[Sjoerd Meijer via Phabricator via cfe-commits]

SjoerdMeijer updated this revision to Diff 246917.
SjoerdMeijer edited the summary of this revision.
SjoerdMeijer added a comment.

> Are there any tests remaining that check that with -fcommon, IR generation creates "common" variables, now that all these tests have been modified?

I've added a RUN line to `clang/test/CodeGen/no-common.c` with `-fcommon` that should test this.

> Suggestion:

Therefore, C code that uses tentative definitions as definitions of a variable in multiple translation units will trigger multiple-definition linker errors. Generally, this occurs when the use of the extern keyword is neglected in the declaration of a variable in a header file. In some cases, no specific translation unit provides a definition of the variable. The previous behavior can be restored by specifying -fcommon.

Thanks for your suggestion. I've verbatim added this to the release note.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D75056/new/

https://reviews.llvm.org/D75056

Files:
  clang/docs/ClangCommandLineReference.rst
  clang/docs/ReleaseNotes.rst
  clang/include/clang/Driver/Options.td
  clang/lib/Driver/ToolChains/Clang.cpp
  clang/lib/Frontend/CompilerInvocation.cpp
  clang/test/CodeGen/2008-07-21-mixed-var-fn-decl.c
  clang/test/CodeGen/2009-10-20-GlobalDebug.c
  clang/test/CodeGen/aarch64-sve.c
  clang/test/CodeGen/address-space.c
  clang/test/CodeGen/alias.c
  clang/test/CodeGen/align-systemz.c
  clang/test/CodeGen/alignment.c
  clang/test/CodeGen/asm-label.c
  clang/test/CodeGen/attr-weak-import.c
  clang/test/CodeGen/attr-weakref2.c
  clang/test/CodeGen/attributes.c
  clang/test/CodeGen/blocks-windows.c
  clang/test/CodeGen/bool-convert.c
  clang/test/CodeGen/c11atomics.c
  clang/test/CodeGen/cfstring-elf-cfbuild-x86_64.c
  clang/test/CodeGen/cfstring-windows.c
  clang/test/CodeGen/default-address-space.c
  clang/test/CodeGen/dllexport-1.c
  clang/test/CodeGen/dllexport.c
  clang/test/CodeGen/dllimport.c
  clang/test/CodeGen/microsoft-no-common-align.c
  clang/test/CodeGen/no-common.c
  clang/test/CodeGen/pr25786.c
  clang/test/CodeGen/pragma-pack-1.c
  clang/test/CodeGen/pragma-weak.c
  clang/test/CodeGen/private-extern-redef.c
  clang/test/CodeGen/tentative-decls.c
  clang/test/CodeGen/tls-model.c
  clang/test/CodeGen/visibility.c
  clang/test/CodeGen/vlt_to_pointer.c
  clang/test/CodeGen/volatile-1.c
  clang/test/CodeGen/weak-global.c
  clang/test/CodeGen/windows-on-arm-dllimport-dllexport.c
  clang/test/CodeGenCXX/clang-sections-tentative.c
  clang/test/CodeGenObjC/constant-string-class.m
  clang/test/CodeGenObjC/tentative-cfconstantstring.m
  clang/test/CodeGenOpenCL/address-spaces.cl
  clang/test/CodeGenOpenCL/amdgpu-nullptr.cl
  clang/test/Driver/apple-kext-mkernel.c
  clang/test/Driver/clang_f_opts.c
  clang/test/Driver/fuchsia.c
  clang/test/Driver/no-common.c
  clang/test/Driver/xcore-opts.c
  clang/test/Frontend/ast-codegen.c
  clang/test/Headers/xmmintrin.c
  clang/test/PCH/chain-external-defs.c
  clang/test/PCH/external-defs.c
  clang/test/PCH/tentative-defs.c
  clang/test/Parser/pragma-visibility2.c

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