From ec2e1cae2c6330cd1e3b7f580702f1949827899a Mon Sep 17 00:00:00 2001 From: Louis Dionne Date: Wed, 9 Oct 2024 08:46:59 -0400 Subject: [PATCH] [libc++] Fix broken configuration system-libcxxabi on Apple (#110920) On Apple platforms, using system-libcxxabi as an ABI library wouldn't work because we'd try to re-export symbols from libc++abi that the system libc++abi.dylib might not have. Instead, only re-export those symbols when we're using the in-tree libc++abi. This does mean that libc++.dylib won't re-export any libc++abi symbols when building against the system libc++abi, which could be fixed in various ways. However, the best solution really depends on the intended use case, so this patch doesn't try to solve that problem. As a drive-by, also improve the diagnostic message when the user forgets to set the LIBCXX_CXX_ABI_INCLUDE_PATHS variable, which would previously lead to a confusing error. Closes #104672 (cherry picked from commit 21da4e7f51c7adfd0b1c5defc8bd0d16ea1ce759) --- libcxx/cmake/Modules/HandleLibCXXABI.cmake | 25 +++++++++++++++++++++- libcxx/src/CMakeLists.txt | 8 ++----- libcxxabi/src/CMakeLists.txt | 2 ++ 3 files changed, 28 insertions(+), 7 deletions(-) diff --git a/libcxx/cmake/Modules/HandleLibCXXABI.cmake b/libcxx/cmake/Modules/HandleLibCXXABI.cmake index 34e9a672a960f9..52236f473f35de 100644 --- a/libcxx/cmake/Modules/HandleLibCXXABI.cmake +++ b/libcxx/cmake/Modules/HandleLibCXXABI.cmake @@ -83,6 +83,10 @@ endfunction() # Link against a system-provided libstdc++ if ("${LIBCXX_CXX_ABI}" STREQUAL "libstdc++") + if(NOT LIBCXX_CXX_ABI_INCLUDE_PATHS) + message(FATAL_ERROR "LIBCXX_CXX_ABI_INCLUDE_PATHS must be set when selecting libstdc++ as an ABI library") + endif() + add_library(libcxx-abi-headers INTERFACE) import_private_headers(libcxx-abi-headers "${LIBCXX_CXX_ABI_INCLUDE_PATHS}" "cxxabi.h;bits/c++config.h;bits/os_defines.h;bits/cpu_defines.h;bits/cxxabi_tweaks.h;bits/cxxabi_forced.h") @@ -96,6 +100,10 @@ if ("${LIBCXX_CXX_ABI}" STREQUAL "libstdc++") # Link against a system-provided libsupc++ elseif ("${LIBCXX_CXX_ABI}" STREQUAL "libsupc++") + if(NOT LIBCXX_CXX_ABI_INCLUDE_PATHS) + message(FATAL_ERROR "LIBCXX_CXX_ABI_INCLUDE_PATHS must be set when selecting libsupc++ as an ABI library") + endif() + add_library(libcxx-abi-headers INTERFACE) import_private_headers(libcxx-abi-headers "${LIBCXX_CXX_ABI_INCLUDE_PATHS}" "cxxabi.h;bits/c++config.h;bits/os_defines.h;bits/cpu_defines.h;bits/cxxabi_tweaks.h;bits/cxxabi_forced.h") @@ -114,7 +122,18 @@ elseif ("${LIBCXX_CXX_ABI}" STREQUAL "libcxxabi") target_compile_definitions(libcxx-abi-headers INTERFACE "-DLIBCXX_BUILDING_LIBCXXABI") if (TARGET cxxabi_shared) - add_library(libcxx-abi-shared ALIAS cxxabi_shared) + add_library(libcxx-abi-shared INTERFACE) + target_link_libraries(libcxx-abi-shared INTERFACE cxxabi_shared) + + # When using the in-tree libc++abi as an ABI library, libc++ re-exports the + # libc++abi symbols (on platforms where it can) because libc++abi is only an + # implementation detail of libc++. + target_link_libraries(libcxx-abi-shared INTERFACE cxxabi-reexports) + + # Populate the OUTPUT_NAME property of libcxx-abi-shared because that is used when + # generating a linker script. + get_target_property(_output_name cxxabi_shared OUTPUT_NAME) + set_target_properties(libcxx-abi-shared PROPERTIES "OUTPUT_NAME" "${_output_name}") endif() if (TARGET cxxabi_static) @@ -131,6 +150,10 @@ elseif ("${LIBCXX_CXX_ABI}" STREQUAL "libcxxabi") # Link against a system-provided libc++abi elseif ("${LIBCXX_CXX_ABI}" STREQUAL "system-libcxxabi") + if(NOT LIBCXX_CXX_ABI_INCLUDE_PATHS) + message(FATAL_ERROR "LIBCXX_CXX_ABI_INCLUDE_PATHS must be set when selecting system-libcxxabi as an ABI library") + endif() + add_library(libcxx-abi-headers INTERFACE) import_private_headers(libcxx-abi-headers "${LIBCXX_CXX_ABI_INCLUDE_PATHS}" "cxxabi.h;__cxxabi_config.h") target_compile_definitions(libcxx-abi-headers INTERFACE "-DLIBCXX_BUILDING_LIBCXXABI") diff --git a/libcxx/src/CMakeLists.txt b/libcxx/src/CMakeLists.txt index 0dfc9647558d46..b9ecbb196694a9 100644 --- a/libcxx/src/CMakeLists.txt +++ b/libcxx/src/CMakeLists.txt @@ -229,14 +229,10 @@ if (LIBCXX_ENABLE_SHARED) target_link_libraries(cxx_shared PUBLIC libcxx-abi-shared) endif() - # Maybe re-export symbols from libc++abi - # In particular, we don't re-export the symbols if libc++abi is merged statically - # into libc++ because in that case there's no dylib to re-export from. + # Maybe force some symbols to be weak, not weak or not exported. + # TODO: This shouldn't depend on the platform, and ideally it should be done in the sources. if (APPLE AND LIBCXX_CXX_ABI MATCHES "libcxxabi$" AND NOT LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY) - target_link_libraries(cxx_shared PRIVATE cxxabi-reexports) - - # TODO: These exports controls should not be tied to whether we re-export libc++abi symbols target_link_libraries(cxx_shared PRIVATE "-Wl,-unexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/libc++unexp.exp" "-Wl,-force_symbols_not_weak_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/notweak.exp" diff --git a/libcxxabi/src/CMakeLists.txt b/libcxxabi/src/CMakeLists.txt index f95a8c471fd39f..1e06b8cbf084d9 100644 --- a/libcxxabi/src/CMakeLists.txt +++ b/libcxxabi/src/CMakeLists.txt @@ -213,6 +213,8 @@ if (LIBCXXABI_ENABLE_SHARED) list(APPEND LIBCXXABI_INSTALL_TARGETS "cxxabi_shared") endif() + # TODO: Move this to libc++'s HandleLibCXXABI.cmake since this is effectively trying to control + # what libc++ re-exports. add_library(cxxabi-reexports INTERFACE) function(export_symbols file) # -exported_symbols_list is only available on Apple platforms