[CMake] Use explicit header path when using in-tree libc++ for tests

[phosek]

Summary

This is a follow up to D118200 which applies a similar cleanup to
headers when using in-tree libc++ to avoid accidentally picking up
the system headers.

[mstorsjo]

(Side question: What's the correct -commits list for discussing compiler-rt patches? They don't get autoassigned any, but probably should, for visibility.)

[mstorsjo]

This looks reasonable to me!

[phosek]

In D128035#3591373, @mstorsjo wrote:

(Side question: What's the correct -commits list for discussing compiler-rt patches? They don't get autoassigned any, but probably should, for visibility.)

I don't see compiler-rt-commits on https://lists.llvm.org/cgi-bin/mailman/listinfo/, perhaps we could request it?

compiler-rt/CMakeLists.txt

 # Remove -stdlib= which is unused when passing -nostdinc++...
 string(REGEX MATCHALL "-stdlib=[a-zA-Z+]*" stdlib_flag "${CMAKE_CXX_FLAGS}")
 string(REGEX REPLACE "-stdlib=[a-zA-Z+]*" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
 
 # ...we need it to build some runtimes and tests so readd it where appropriate.
 list(APPEND COMPILER_RT_COMMON_CFLAGS ${stdlib_flag})
 list(APPEND COMPILER_RT_COMMON_LINK_FLAGS ${stdlib_flag})
 
+# 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 " ${stdlib_flag}")
+
+# When cross-compiling, COMPILER_RT_TEST_COMPILER_CFLAGS help in compilation
+# and linking of unittests.
+string(REPLACE " " ";" COMPILER_RT_UNITTEST_CFLAGS "${COMPILER_RT_TEST_COMPILER_CFLAGS}")
+set(COMPILER_RT_UNITTEST_LINK_FLAGS ${COMPILER_RT_UNITTEST_CFLAGS})
+
 if(COMPILER_RT_USE_LLVM_UNWINDER)
   if (COMPILER_RT_ENABLE_STATIC_UNWINDER)
     set(unwinder_target unwind_static)
   else()
     set(unwinder_target unwind_shared)
   endif()
   list(APPEND SANITIZER_CXX_ABI_LIBRARIES "$<$<TARGET_EXISTS:${unwinder_target}>:$<TARGET_LINKER_FILE:${unwinder_target}>>")
 endif()

 
 if (SANITIZER_TEST_CXX_LIBNAME STREQUAL "libc++")
   if (SANITIZER_TEST_CXX_INTREE)
     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}>>")
+    list(APPEND SANITIZER_TEST_CXX_LIBRARIES "$<$<TARGET_EXISTS:${cxx_target}>:$<TARGET_LINKER_FILE:${cxx_target}>>")
+    list(APPEND SANITIZER_TEST_CXX_CFLAGS "$<$<TARGET_EXISTS:cxx-headers>:-isystem$<JOIN:$<TARGET_PROPERTY:cxx-headers,INTERFACE_INCLUDE_DIRECTORIES>,$<SEMICOLON>-isystem>>")
+    # We are using the in tree libc++ so avoid including the default one.
+    append_list_if(COMPILER_RT_HAS_NOSTDINCXX_FLAG -nostdinc++ COMPILER_RT_UNITTEST_CFLAGS)
+    append_list_if(COMPILER_RT_HAS_NOSTDLIBXX_FLAG -nostdlib++ COMPILER_RT_UNITTEST_LINK_FLAGS)
   else()
     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 -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 " ${stdlib_flag}")
-
-# When cross-compiling, COMPILER_RT_TEST_COMPILER_CFLAGS help in compilation
-# and linking of unittests.
-string(REPLACE " " ";" COMPILER_RT_UNITTEST_CFLAGS "${COMPILER_RT_TEST_COMPILER_CFLAGS}")
-set(COMPILER_RT_UNITTEST_LINK_FLAGS ${COMPILER_RT_UNITTEST_CFLAGS})
-
 # Unittests support.
 set(COMPILER_RT_GTEST_PATH ${LLVM_MAIN_SRC_DIR}/utils/unittest/googletest)
 set(COMPILER_RT_GTEST_SOURCE ${COMPILER_RT_GTEST_PATH}/src/gtest-all.cc)
 set(COMPILER_RT_GTEST_CFLAGS
   -DGTEST_NO_LLVM_SUPPORT=1
   -DGTEST_HAS_RTTI=0
   -I${COMPILER_RT_GTEST_PATH}/include
   -I${COMPILER_RT_GTEST_PATH}

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

 include(CheckCXXCompilerFlag)
 include(CompilerRTCompile)
 include(CompilerRTLink)
 
 set(MEMPROF_UNITTEST_CFLAGS
   ${COMPILER_RT_UNITTEST_CFLAGS}
+  ${SANITIZER_TEST_CXX_CFLAGS}
   ${COMPILER_RT_GTEST_CFLAGS}
   ${COMPILER_RT_GMOCK_CFLAGS}
   -I${COMPILER_RT_SOURCE_DIR}/lib/
   -O2
   -g
   -fno-rtti
   -Wno-pedantic
   -fno-omit-frame-pointer)

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

 include_directories(..)
 
 add_custom_target(ScudoUnitTests)
 set_target_properties(ScudoUnitTests PROPERTIES
   FOLDER "Compiler-RT Tests")
 
 set(SCUDO_UNITTEST_CFLAGS
   ${COMPILER_RT_UNITTEST_CFLAGS}
+  ${SANITIZER_TEST_CXX_CFLAGS}
   ${COMPILER_RT_GTEST_CFLAGS}
   -I${COMPILER_RT_SOURCE_DIR}/include
   -I${COMPILER_RT_SOURCE_DIR}/lib
   -I${COMPILER_RT_SOURCE_DIR}/lib/scudo/standalone
   -I${COMPILER_RT_SOURCE_DIR}/lib/scudo/standalone/include
   -DGTEST_HAS_RTTI=0
   -g
   # Extra flags for the C++ tests

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

 include_directories(../rtl)
 
 add_custom_target(TsanUnitTests)
 set_target_properties(TsanUnitTests PROPERTIES
   FOLDER "Compiler-RT Tests")
 
 set(TSAN_UNITTEST_CFLAGS
   ${COMPILER_RT_UNITTEST_CFLAGS}
+  ${SANITIZER_TEST_CXX_CFLAGS}
   ${COMPILER_RT_GTEST_CFLAGS}
   -I${COMPILER_RT_SOURCE_DIR}/include
   -I${COMPILER_RT_SOURCE_DIR}/lib
   -I${COMPILER_RT_SOURCE_DIR}/lib/tsan/rtl
   -DGTEST_HAS_RTTI=0
   -fno-rtti
 )