[CMake] Use generator expression to get in-tree libc++ path

[phosek]

Summary

When using the in-tree libc++, we should be using the full path to
ensure that we're using the right library and not accidentally pick up
the system library.

[abrachet]

compiler-rt/CMakeLists.txt

540

Can $<BOOL:$<TARGET_NAME_IF_EXISTS:${cxx_target}>> ever evaluate false here?

compiler-rt/lib/memprof/tests/CMakeLists.txt

39–40

Stylistically should this instead append to MEMPROF_UNITTEST_LINK_FLAGS? Everywhere else you have added SANITIZER_TEST_CXX_LIBRARIES to their respective *LINK_FLAGS.

[ldionne]

I don't know compiler-rt much, but this looks reasonable.

[phosek]

compiler-rt/CMakeLists.txt

540

If the target doesn't exist, $<TARGET_NAME_IF_EXISTS:${cxx_target}> will evaluate to empty string and $<BOOL:$<TARGET_NAME_IF_EXISTS:${cxx_target}>> should evaluate that to false.

compiler-rt/lib/memprof/tests/CMakeLists.txt

39–40

Good question, I think that target_link_libraries is the correct solution because it handles other aspects like visibility (e.g. PRIVATE, PUBLIC). The reason we only use it here is because this is the only test that uses add_executable, all other tests use the generate_compiler_rt_tests function which internally uses add_compiler_rt_test which handles the compilation and linking manually via add_custom_command (this is so that it can use a custom compiler rather than CMAKE_{C,CXX}_COMPILER), see https://github.com/llvm/llvm-project/blob/db0631096e59c71b6f6b034306327b42d9184184/compiler-rt/cmake/Modules/AddCompilerRT.cmake#L497.

What I'm considering as a follow up is to (1) change MemProfUnitTests to also use generate_compiler_rt_tests for consistency with other tests and (2) change add_compiler_rt_test to use add_executable and other common CMake infrastructure.

[tambre]

compiler-rt/CMakeLists.txt

542–545

Why the explicit -l? Per the documentation it's considered as a linker flag while without as a plain library name (unless a target or a full path). I'd wager we mean the latter, so would be nice to use that.

[phosek]

compiler-rt/CMakeLists.txt

542–545

generate_compiler_rt_tests doesn't use target_link_libraries, it directly invokes the compiler which wouldn't handle plain library name unless it's a full path.

compiler-rt/CMakeLists.txt

 elseif (SANITIZER_CXX_ABI_LIBNAME STREQUAL "libcxxabi")
   list(APPEND SANITIZER_CXX_ABI_LIBRARIES "c++abi")
 elseif (SANITIZER_CXX_ABI_LIBNAME STREQUAL "libstdc++")
   append_list_if(COMPILER_RT_HAS_LIBSTDCXX stdc++ SANITIZER_CXX_ABI_LIBRARIES)
 endif()
 
 if (SANITIZER_TEST_CXX_LIBNAME STREQUAL "libc++")
   if (SANITIZER_TEST_CXX_INTREE)
-    if (SANITIZER_USE_STATIC_TEST_CXX AND (TARGET cxx_static OR HAVE_LIBCXX))
-      list(APPEND SANITIZER_TEST_CXX_LIBRARIES cxx_static)
-    elseif (TARGET cxx_shared OR HAVE_LIBCXX)
-      list(APPEND SANITIZER_TEST_CXX_LIBRARIES cxx_shared)
+    if (SANITIZER_USE_STATIC_TEST_CXX)
+      set(cxx_target cxx_static)
+    else()
+      set(cxx_target cxx_shared)
     endif()
+    list(APPEND SANITIZER_TEST_CXX_LIBRARIES "$<$<BOOL:$<TARGET_NAME_IF_EXISTS:${cxx_target}>>:$<TARGET_LINKER_FILE:${cxx_target}>>")
   else()
-    append_list_if(COMPILER_RT_HAS_LIBCXX c++ SANITIZER_TEST_CXX_LIBRARIES)
+    append_list_if(COMPILER_RT_HAS_LIBCXX -lc++ SANITIZER_TEST_CXX_LIBRARIES)
   endif()
 elseif (SANITIZER_TEST_CXX_LIBNAME STREQUAL "libstdc++")
-  append_list_if(COMPILER_RT_HAS_LIBSTDCXX stdc++ SANITIZER_TEST_CXX_LIBRARIES)
+  append_list_if(COMPILER_RT_HAS_LIBSTDCXX -lstdc++ SANITIZER_TEST_CXX_LIBRARIES)
 endif()
 
 # TODO: There's a lot of duplication across lib/*/tests/CMakeLists.txt files,
 # move some of the common flags to COMPILER_RT_UNITTEST_CFLAGS.
 
 # Unittests need access to C++ standard library.
 string(APPEND COMPILER_RT_TEST_COMPILER_CFLAGS " ${stdlib_flag}")
 

compiler-rt/lib/memprof/tests/CMakeLists.txt

 
 set(MEMPROF_UNIT_TEST_HEADERS
   ${MEMPROF_HEADERS})
 
 if(NOT WIN32)
   list(APPEND MEMPROF_UNITTEST_LINK_FLAGS -pthread)
 endif()
 
-foreach(lib ${SANITIZER_TEST_CXX_LIBRARIES})
-  list(APPEND MEMPROF_UNITTEST_LINK_FLAGS -l${lib})
-endforeach()
+set(MEMPROF_UNITTEST_LINK_LIBRARIES ${SANITIZER_TEST_CXX_LIBRARIES})
+list(APPEND MEMPROF_UNITTEST_LINK_LIBRARIES "dl")
 
 if(COMPILER_RT_DEFAULT_TARGET_ARCH IN_LIST MEMPROF_SUPPORTED_ARCH)
   # MemProf unit tests are only run on the host machine.
   set(arch ${COMPILER_RT_DEFAULT_TARGET_ARCH})
 
   add_executable(MemProfUnitTests 
     ${MEMPROF_UNITTESTS}
     ${COMPILER_RT_GTEST_SOURCE}
     ${COMPILER_RT_GMOCK_SOURCE}
     ${MEMPROF_SOURCES}
     $<TARGET_OBJECTS:RTSanitizerCommon.${arch}>
     $<TARGET_OBJECTS:RTSanitizerCommonCoverage.${arch}>
     $<TARGET_OBJECTS:RTSanitizerCommonLibc.${arch}>
     $<TARGET_OBJECTS:RTSanitizerCommonSymbolizer.${arch}>)
   set_target_compile_flags(MemProfUnitTests ${MEMPROF_UNITTEST_CFLAGS})
   set_target_link_flags(MemProfUnitTests ${MEMPROF_UNITTEST_LINK_FLAGS})
-  target_link_libraries(MemProfUnitTests dl)
+  target_link_libraries(MemProfUnitTests ${MEMPROF_UNITTEST_LINK_LIBRARIES})
 
   if (TARGET cxx-headers OR HAVE_LIBCXX)
     add_dependencies(MemProfUnitTests cxx-headers)
   endif()
 
   set_target_properties(MemProfUnitTests PROPERTIES
     RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
 endif()

compiler-rt/lib/orc/unittests/CMakeLists.txt

function(get_orc_lib_for_arch arch lib)
   endif()
   set(${lib} "${tgt_name}" PARENT_SCOPE)
 endfunction()
 
 set(ORC_TEST_ARCH ${ORC_SUPPORTED_ARCH})
 set(ORC_UNITTEST_LINK_FLAGS
   ${COMPILER_RT_UNITTEST_LINK_FLAGS}
   ${CMAKE_THREAD_LIBS_INIT}
+  ${SANITIZER_TEST_CXX_LIBRARIES}
   )
 
 if(APPLE)
   darwin_filter_host_archs(ORC_SUPPORTED_ARCH ORC_TEST_ARCH)
   list(APPEND ORC_UNITTEST_CFLAGS ${DARWIN_osx_CFLAGS})
   list(APPEND ORC_UNITTEST_LINK_FLAGS ${DARWIN_osx_LINK_FLAGS})
 else()
   append_list_if(COMPILER_RT_HAS_LIBM -lm ORC_UNITTEST_LINK_FLAGS)
   append_list_if(COMPILER_RT_HAS_LIBRT -lrt ORC_UNITTEST_LINK_FLAGS)
   append_list_if(COMPILER_RT_HAS_LIBDL -ldl ORC_UNITTEST_LINK_FLAGS)
   append_list_if(COMPILER_RT_HAS_LIBPTHREAD -pthread ORC_UNITTEST_LINK_FLAGS)
   append_list_if(COMPILER_RT_HAS_LIBEXECINFO -lexecinfo ORC_UNITTEST_LINK_FLAGS)
 endif()
 
-foreach(lib ${SANITIZER_TEST_CXX_LIBRARIES})
-  list(APPEND ORC_UNITTEST_LINK_FLAGS -l${lib})
-endforeach()
-
 set(ORC_DEPS gtest orc)
 # ORC uses C++ standard library headers.
 if (TARGET cxx-headers OR HAVE_LIBCXX)
   set(ORC_DEPS cxx-headers)
 endif()
 
 macro(add_orc_unittest testname)
   cmake_parse_arguments(TEST "" "" "SOURCES;HEADERS" ${ARGN})

compiler-rt/lib/scudo/standalone/tests/CMakeLists.txt

 if (COMPILER_RT_HAS_GWP_ASAN)
   list(APPEND SCUDO_UNITTEST_CFLAGS -DGWP_ASAN_HOOKS -fno-omit-frame-pointer
        -mno-omit-leaf-frame-pointer)
 endif()
 
 set(SCUDO_TEST_ARCH ${SCUDO_STANDALONE_SUPPORTED_ARCH})
 
 # gtests requires c++
-set(LINK_FLAGS ${COMPILER_RT_UNITTEST_LINK_FLAGS})
-foreach(lib ${SANITIZER_TEST_CXX_LIBRARIES})
-  list(APPEND LINK_FLAGS -l${lib})
-endforeach()
+set(LINK_FLAGS
+  ${COMPILER_RT_UNITTEST_LINK_FLAGS}
+  ${SANITIZER_TEST_CXX_LIBRARIES}
+  )
 list(APPEND LINK_FLAGS -pthread)
 # Linking against libatomic is required with some compilers
 check_library_exists(atomic __atomic_load_8 "" COMPILER_RT_HAS_LIBATOMIC)
 if (COMPILER_RT_HAS_LIBATOMIC)
   list(APPEND LINK_FLAGS -latomic)
 endif()
 
 set(SCUDO_TEST_HEADERS

compiler-rt/lib/tsan/tests/CMakeLists.txt

if(COMPILER_RT_TSAN_DEBUG_OUTPUT)
   list(APPEND TSAN_UNITTEST_CFLAGS -DTSAN_COLLECT_STATS=1
                                    -DTSAN_DEBUG_OUTPUT=2)
 endif()
 
 append_list_if(COMPILER_RT_HAS_MSSE4_2_FLAG -msse4.2 TSAN_UNITTEST_CFLAGS)
 
 set(TSAN_TEST_ARCH ${TSAN_SUPPORTED_ARCH})
 
-set(LINK_FLAGS ${COMPILER_RT_UNITTEST_LINK_FLAGS})
-foreach(lib ${SANITIZER_TEST_CXX_LIBRARIES})
-  list(APPEND LINK_FLAGS -l${lib})
-endforeach()
+set(LINK_FLAGS
+  ${COMPILER_RT_UNITTEST_LINK_FLAGS}
+  ${SANITIZER_TEST_CXX_LIBRARIES}
+  )
 
 if(APPLE)
 
   # Create a static library for test dependencies.
   set(TSAN_TEST_RUNTIME_OBJECTS
     $<TARGET_OBJECTS:RTTsan_dynamic.osx>
     $<TARGET_OBJECTS:RTInterception.osx>
     $<TARGET_OBJECTS:RTSanitizerCommon.osx>

compiler-rt/lib/xray/tests/CMakeLists.txt

function(get_xray_lib_for_arch arch lib)
   endif()
   set(${lib} "${tgt_name}" PARENT_SCOPE)
 endfunction()
 
 set(XRAY_TEST_ARCH ${XRAY_SUPPORTED_ARCH})
 set(XRAY_UNITTEST_LINK_FLAGS
   ${COMPILER_RT_UNITTEST_LINK_FLAGS}
   ${CMAKE_THREAD_LIBS_INIT}
+  ${SANITIZER_TEST_CXX_LIBRARIES}
   )
 
 if (NOT APPLE)
   # Needed by LLVMSupport.
   append_list_if(
     LLVM_ENABLE_TERMINFO
     -l${COMPILER_RT_TERMINFO_LIB} XRAY_UNITTEST_LINK_FLAGS)
 
if (NOT APPLE)
 
   append_list_if(COMPILER_RT_HAS_LIBM -lm XRAY_UNITTEST_LINK_FLAGS)
   append_list_if(COMPILER_RT_HAS_LIBRT -lrt XRAY_UNITTEST_LINK_FLAGS)
   append_list_if(COMPILER_RT_HAS_LIBDL -ldl XRAY_UNITTEST_LINK_FLAGS)
   append_list_if(COMPILER_RT_HAS_LIBPTHREAD -pthread XRAY_UNITTEST_LINK_FLAGS)
   append_list_if(COMPILER_RT_HAS_LIBEXECINFO -lexecinfo XRAY_UNITTEST_LINK_FLAGS)
 endif()
 
-foreach(lib ${SANITIZER_TEST_CXX_LIBRARIES})
-  list(APPEND XRAY_UNITTEST_LINK_FLAGS -l${lib})
-endforeach()
-
 macro(add_xray_unittest testname)
   cmake_parse_arguments(TEST "" "" "SOURCES;HEADERS" ${ARGN})
   if(UNIX AND NOT APPLE)
     set(CMAKE_DL_LIBS_INIT "")
     foreach(arch ${XRAY_TEST_ARCH})
       set(TEST_OBJECTS)
       get_xray_lib_for_arch(${arch} XRAY_RUNTIME_LIBS)
       generate_compiler_rt_tests(TEST_OBJECTS