links agains libc++ only when present

Author: mpromonet

.cirrus.yml

@@ -37,7 +37,7 @@ linuxarmv7_docker_builder:
     docker info
     export TAG=${CIRRUS_TAG:-${CIRRUS_BRANCH}}
     [ "$TAG" == "master" ] && export TAG=latest
-    docker build -t $CIRRUS_REPO_FULL_NAME:${TAG}-armv7 . -f Dockerfile.rpi --build-arg ARCH=armv7l --build-arg CROSSCOMPILER=https://altushost-swe.dl.sourceforge.net/project/raspberry-pi-cross-compilers/Raspberry%20Pi%20GCC%20Cross-Compiler%20Toolchains/Buster/GCC%2010.2.0/Raspberry%20Pi%202%2C%203/cross-gcc-10.2.0-pi_2-3.tar.gz --build-arg IMAGE=balenalib/raspberry-pi2
+    docker build -t $CIRRUS_REPO_FULL_NAME:${TAG}-armv7 . -f Dockerfile.rpi --build-arg IMAGE=balenalib/raspberry-pi2 --build-arg ARCH=armv7l --build-arg CROSSCOMPILER=https://downloads.sourceforge.net/project/raspberry-pi-cross-compilers/Raspberry%20Pi%20GCC%20Cross-Compiler%20Toolchains/Bookworm/GCC%2014.2.0/Raspberry%20Pi%202%2C%203/cross-gcc-14.2.0-pi_2-3.tar.gz
     docker login --username=$DOCKERHUB_USER --password=$DOCKERHUB_PASS 
     #docker push $CIRRUS_REPO_FULL_NAME:${TAG}-armv7
 
@@ -59,7 +59,7 @@ linuxarmv6_docker_builder:
     docker info
     export TAG=${CIRRUS_TAG:-${CIRRUS_BRANCH}}
     [ "$TAG" == "master" ] && export TAG=latest
-    docker build -t $CIRRUS_REPO_FULL_NAME:${TAG}-armv6 . -f Dockerfile.rpi
+    docker build -t $CIRRUS_REPO_FULL_NAME:${TAG}-armv6 . -f Dockerfile.rpi --build-arg CROSSCOMPILER=https://downloads.sourceforge.net/project/raspberry-pi-cross-compilers/Raspberry%20Pi%20GCC%20Cross-Compiler%20Toolchains/Bookworm/GCC%2014.2.0/Raspberry%20Pi%201%2C%20Zero/cross-gcc-14.2.0-pi_0-1.tar.gz
     docker login --username=$DOCKERHUB_USER --password=$DOCKERHUB_PASS 
     #docker push $CIRRUS_REPO_FULL_NAME:${TAG}-armv6
 

CMakeLists.txt

@@ -20,6 +20,7 @@ set (CMAKE_CXX_EXTENSIONS OFF)
 # set CMAKE_FIND_ROOT_PATH to search package in WebRTC sysroot
 if(CMAKE_SYSTEM_PROCESSOR MATCHES "armv.*")
   set (CMAKE_FIND_ROOT_PATH ${WEBRTCROOT}/src/build/linux/debian_bullseye_arm-sysroot)
+  add_compile_options(--sysroot=${CMAKE_FIND_ROOT_PATH})
 elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "arm64")
   set (CMAKE_FIND_ROOT_PATH ${WEBRTCROOT}/src/build/linux/debian_bullseye_arm64-sysroot)
   add_compile_options(--sysroot=${CMAKE_FIND_ROOT_PATH})
@@ -225,7 +226,16 @@ if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -I${WEBRTCROOT}/src/buildtools/third_party/libc++ -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_EXTENSIVE")
   else()
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -I${WEBRTCROOT}/src/buildtools/third_party/libc++ -nostdinc++ -isystem${WEBRTCROOT}/src/third_party/libc++/src/include -isystem${WEBRTCROOT}/src/third_party/libc++abi/src/include -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_EXTENSIVE")
-    target_link_libraries(${CMAKE_PROJECT_NAME} "${WEBRTCOBJS}/buildtools/third_party/libc++/${CMAKE_STATIC_LIBRARY_PREFIX}c++${CMAKE_STATIC_LIBRARY_SUFFIX}" "${WEBRTCOBJS}/buildtools/third_party/libc++abi/${CMAKE_STATIC_LIBRARY_PREFIX}c++abi${CMAKE_STATIC_LIBRARY_SUFFIX}")
+    find_library(LIBC++ NAMES c++ HINTS "${WEBRTCOBJS}/buildtools/third_party" NO_DEFAULT_PATH)
+    if (LIBC++)
+      message(STATUS "Found libc++ library at ${LIBC++}")
+      target_link_libraries(${CMAKE_PROJECT_NAME} "${LIBC++}")
+    endif()
+    find_library(LIBC++ABI NAMES c++abi HINTS "${WEBRTCOBJS}/buildtools/third_party" NO_DEFAULT_PATH)
+    if (LIBC++ABI)
+      message(STATUS "Found libc++abi library at ${LIBC++ABI}")
+      target_link_libraries(${CMAKE_PROJECT_NAME} "${LIBC++ABI}")
+    endif()
   endif()
 endif()