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[libunwind] Remove checks for -nostdlib++ (#143162)

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libunwind uses a C linker, so it's never even trying to link against any
C++ libraries. This removes the code which tries to drop C++ libraries,
which makes the CMake configuration simpler and allows for upgrading
GCC.
This commit is contained in:
Nikolas Klauser 2025-06-11 11:43:34 +02:00 committed by GitHub
parent 9797b5fcfb
commit c59cc2b690
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GPG Key ID: B5690EEEBB952194
2 changed files with 0 additions and 68 deletions
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56
libunwind/cmake/config-ix.cmake
View File

@ -26,62 +26,6 @@ if (NOT LIBUNWIND_USE_COMPILER_RT)
endif ()
endif()
# libunwind is using -nostdlib++ at the link step when available,
# otherwise -nodefaultlibs is used. We want all our checks to also
# use one of these options, otherwise we may end up with an inconsistency between
# the flags we think we require during configuration (if the checks are
# performed without one of those options) and the flags that are actually
# required during compilation (which has the -nostdlib++ or -nodefaultlibs). libc is
# required for the link to go through. We remove sanitizers from the
# configuration checks to avoid spurious link errors.
llvm_check_compiler_linker_flag(CXX "-nostdlib++" CXX_SUPPORTS_NOSTDLIBXX_FLAG)
if (CXX_SUPPORTS_NOSTDLIBXX_FLAG)
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nostdlib++")
else()
llvm_check_compiler_linker_flag(C "-nodefaultlibs" C_SUPPORTS_NODEFAULTLIBS_FLAG)
if (C_SUPPORTS_NODEFAULTLIBS_FLAG)
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nodefaultlibs")
endif()
endif()
# Only link against compiler-rt manually if we use -nodefaultlibs, since
# otherwise the compiler will do the right thing on its own.
if (NOT CXX_SUPPORTS_NOSTDLIBXX_FLAG AND C_SUPPORTS_NODEFAULTLIBS_FLAG)
if (LIBUNWIND_HAS_C_LIB)
list(APPEND CMAKE_REQUIRED_LIBRARIES c)
endif ()
if (LIBUNWIND_HAS_ROOT_LIB)
list(APPEND CMAKE_REQUIRED_LIBRARIES root)
endif ()
if (LIBUNWIND_USE_COMPILER_RT)
include(HandleCompilerRT)
find_compiler_rt_library(builtins LIBUNWIND_BUILTINS_LIBRARY
FLAGS ${LIBUNWIND_COMPILE_FLAGS})
list(APPEND CMAKE_REQUIRED_LIBRARIES "${LIBUNWIND_BUILTINS_LIBRARY}")
else ()
if (LIBUNWIND_HAS_GCC_S_LIB)
list(APPEND CMAKE_REQUIRED_LIBRARIES gcc_s)
endif ()
if (LIBUNWIND_HAS_GCC_LIB)
list(APPEND CMAKE_REQUIRED_LIBRARIES gcc)
endif ()
endif ()
if (MINGW)
# Mingw64 requires quite a few "C" runtime libraries in order for basic
# programs to link successfully with -nodefaultlibs.
if (LIBUNWIND_USE_COMPILER_RT)
set(MINGW_RUNTIME ${LIBUNWIND_BUILTINS_LIBRARY})
else ()
set(MINGW_RUNTIME gcc_s gcc)
endif()
set(MINGW_LIBRARIES mingw32 ${MINGW_RUNTIME} moldname mingwex msvcrt advapi32
shell32 user32 kernel32 mingw32 ${MINGW_RUNTIME}
moldname mingwex msvcrt)
list(APPEND CMAKE_REQUIRED_LIBRARIES ${MINGW_LIBRARIES})
endif()
endif()
if (CXX_SUPPORTS_NOSTDLIBXX_FLAG OR C_SUPPORTS_NODEFAULTLIBS_FLAG)
if (CMAKE_C_FLAGS MATCHES -fsanitize OR CMAKE_CXX_FLAGS MATCHES -fsanitize)
set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize=all")

12
libunwind/src/CMakeLists.txt
View File

@ -71,18 +71,6 @@ set(LIBUNWIND_SOURCES
${LIBUNWIND_ASM_SOURCES})
# Generate library list.
if (CXX_SUPPORTS_NOSTDLIBXX_FLAG)
add_link_flags_if_supported(-nostdlib++)
else()
if (LIBUNWIND_USE_COMPILER_RT)
add_library_flags("${LIBUNWIND_BUILTINS_LIBRARY}")
else()
add_library_flags_if(LIBUNWIND_HAS_GCC_S_LIB gcc_s)
add_library_flags_if(LIBUNWIND_HAS_GCC_LIB gcc)
endif()
add_library_flags_if(LIBUNWIND_HAS_C_LIB c)
endif()
if (NOT APPLE)
add_library_flags_if(LIBUNWIND_HAS_DL_LIB dl)
endif()