From ac70933783a70d5387a2bb2849c568e33ba52558 Mon Sep 17 00:00:00 2001 From: Khem Raj Date: Sat, 21 Jan 2023 01:41:32 -0800 Subject: [PATCH] cmake: Use -idirafter instead of -isystem isystem dirs are searched before the regular system dirs this exposes an interesting include ordering problem when using clang + libc++, when including C++ headers like cstdlib includes stdlib.h and in case of libc++, this should be coming from libc++ as well, which is then eventually including system stdlib.h libc++ has added a check for checking this order recently, which means if cstlib ends up including system stdlib.h before libc++ provided stdlib.h it errors out | /mnt/b/yoe/master/build/tmp/work/riscv64-yoe-linux/libcereal/1.3.2+gitAUTOINC+ebef1e9298-r0/recipe-sysroot/usr/include/c++/v1/cwchar:113:5: error: tried including but didn't find libc++'s header. This usually means that your header search paths are not configured properly. The header search paths should contain the C++ Standard Library headers before any C Standard Library, and you are probably using compiler flags that make that not be the case. | # error tried including but didn't find libc++'s header. \ | ^ The reason is that include_directories with SYSTEM property adds the directory via -system and some of these directories point to sysroot e.g. OPENSSL_INCLUDE_DIR which ends up adding -isystem /usr/include and causes the system stdlib.h to included before libc++ stdlib.h A fix is to use -idirafter which preserved the effects of system headers but instead of prepending, it will append to system headers and the issue is addressed Signed-off-by: Khem Raj --- unittests/boost/CMakeLists.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/unittests/boost/CMakeLists.txt b/unittests/boost/CMakeLists.txt index 1d733bc75..08e6a169f 100644 --- a/unittests/boost/CMakeLists.txt +++ b/unittests/boost/CMakeLists.txt @@ -1,6 +1,6 @@ file(GLOB TESTS RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} *.cpp) -include_directories(SYSTEM ${Boost_INCLUDE_DIRS}) +set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -idirafter ${Boost_INCLUDE_DIRS}") # Build all of the non-special tests foreach(TEST_SOURCE ${TESTS})