Why "all warnings being treated as errors" occurs even added "set(CMAKE_COMPILE_WARNING_AS_ERROR OFF)" to CMakeLists.txt?

Question

I'm building the llvm-18.1.3 and facing the all warnings being treated as errors error as follows:

/home/pi/llvm-project-llvmorg-18.1.3/libc/src/stdlib/bsearch.cpp:16:28: error: ‘void* __llvm_libc_18_1_3_::bsearch(const void*, const void*, size_t, size_t, int (*)(const void*, const void*))’ aliased to external symbol ‘bsearch’
   16 | LLVM_LIBC_FUNCTION(void *, bsearch,
      |                            ^~~~~~~
/home/pi/llvm-project-llvmorg-18.1.3/libc/src/__support/common.h:28:34: note: in definition of macro ‘LLVM_LIBC_FUNCTION_IMPL’
   28 |   decltype(LIBC_NAMESPACE::name) name [[gnu::alias(#name)]];                   \
      |                                  ^~~~
/home/pi/llvm-project-llvmorg-18.1.3/libc/src/stdlib/bsearch.cpp:16:1: note: in expansion of macro ‘LLVM_LIBC_FUNCTION’
   16 | LLVM_LIBC_FUNCTION(void *, bsearch,
      | ^~~~~~~~~~~~~~~~~~
/home/pi/llvm-project-llvmorg-18.1.3/libc/src/stdlib/bsearch.cpp:16:28: error: ‘void* __llvm_libc_18_1_3_::bsearch(const void*, const void*, size_t, size_t, int (*)(const void*, const void*))’ specifies less restrictive attribute than its target ‘void* bsearch(const void*, const void*, size_t, size_t, __compar_fn_t)’: ‘nonnull’ [-Werror=missing-attributes]
   16 | LLVM_LIBC_FUNCTION(void *, bsearch,
      |                            ^~~~~~~
/home/pi/llvm-project-llvmorg-18.1.3/libc/src/__support/common.h:28:34: note: in definition of macro ‘LLVM_LIBC_FUNCTION_IMPL’
   28 |   decltype(LIBC_NAMESPACE::name) name [[gnu::alias(#name)]];                   \
      |                                  ^~~~
/home/pi/llvm-project-llvmorg-18.1.3/libc/src/stdlib/bsearch.cpp:16:1: note: in expansion of macro ‘LLVM_LIBC_FUNCTION’
   16 | LLVM_LIBC_FUNCTION(void *, bsearch,
      | ^~~~~~~~~~~~~~~~~~
In file included from /usr/include/stdlib.h:846,
                 from /usr/include/c++/12/cstdlib:75,
                 from /usr/include/c++/12/stdlib.h:36,
                 from /home/pi/llvm-project-llvmorg-18.1.3/libc/src/stdlib/bsearch.h:12,
                 from /home/pi/llvm-project-llvmorg-18.1.3/libc/src/stdlib/bsearch.cpp:9:
/usr/include/arm-linux-gnueabihf/bits/stdlib-bsearch.h:20:1: note: ‘void* __llvm_libc_18_1_3_::bsearch(const void*, const void*, size_t, size_t, int (*)(const void*, const void*))’ target declared here
   20 | bsearch (const void *__key, const void *__base, size_t __nmemb, size_t __size,
      | ^~~~~~~
cc1plus: all warnings being treated as errors

So, I've added set(CMAKE_COMPILE_WARNING_AS_ERROR OFF) line to the end of the file libc/src/stdlib/CMakeLists.txt as follow:

…
if(LIBC_TARGET_ARCHITECTURE_IS_GPU)
  add_entrypoint_object(
    malloc
    ALIAS
    DEPENDS
      .${LIBC_TARGET_OS}.malloc
  )

  add_entrypoint_object(
    free
    ALIAS
    DEPENDS
      .${LIBC_TARGET_OS}.free
  )
endif()

set(CMAKE_COMPILE_WARNING_AS_ERROR OFF)

Then, I built again, however, this error continues. What is my fixing wrong and how can I fix this build breaking?

P.S. The cmake is called as follows:

cmake --compile-no-warning-as-error -S llvm -B build -G Ninja -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_INSTALL_PREFIX=/usr/local -DLLVM_TARGETS_TO_BUILD="ARM;X86;AArch64" -DLLVM_USE_LINKER=gold -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra;cross-project-tests;libc;libclc;lld;lldb;mlir;openmp;polly;pstl;bolt;compiler-rt" -DBUILD_SHARED_LIBS=ON -DLLVM_USE_SPLIT_DWARF=ON -DLLVM_ENABLE_RUNTIMES='libcxx;libcxxabi;libunwind' -DCMAKE_SHARED_LINKER_FLAGS='-latomic'

Tsyvarev · Accepted Answer · 2024-05-11 09:18:08Z

1

Setting variable CMAKE_COMPILE_WARNING_AS_ERROR affects only on targets created after that setting. That is, the variable should be set in the beginning of CMakeLists.txt, not at the end of it.

More precise, whenever a library or executable target is created, its property COMPILE_WARNING_AS_ERROR takes the value from the variable CMAKE_COMPILE_WARNING_AS_ERROR. That is, for create a target with the property set to OFF, the variable should already be set to that value.

answered May 11, 2024 at 9:18

Tsyvarev

67.7k18 gold badges141 silver badges187 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Ueda Takeyuki Over a year ago

Thank you Tsyarev. I've moved set(CMAKE_COMPILE_WARNING_AS_ERROR OFF) from end of file CmakeList.txt to top. But, result was same, still same error.

Ueda Takeyuki Over a year ago

I've added cmake call.

usr1234567 · Accepted Answer · 2024-05-12 18:08:51Z

1

You should not modify the CMakeLists.txt. Instead, add the right parameter to set the according CMake variable when calling cmake.

In your case, setting LLVM_ENABLE_WERROR to OFF should do the trick (cmake -DLLVM_ENABLE_WERROR=OFF <path-to-source>). According to LLVM's documentation, this should be the default value. Please investigate why this is set differently for you.

edited May 12, 2024 at 18:08

answered May 11, 2024 at 6:15

usr1234567

23.8k20 gold badges125 silver badges141 bronze badges

Collectives™ on Stack Overflow

Why "all warnings being treated as errors" occurs even added "set(CMAKE_COMPILE_WARNING_AS_ERROR OFF)" to CMakeLists.txt?

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related