[CMake] Handle in-tree libc++ for sanitizer tests

[phosek]

Summary

We have been relying on the logic for C++ ABI library for sanitizer
tests but that's incorrect since most tests require a full C++ library
and not just C++ ABI. This change tries to address this by using the
dependency on libc++ if available.

[ldionne]

compiler-rt/CMakeLists.txt

535

You just triggered a huge red flag for me by using HAVE_LIBCXX. I hate that thing, it's a ad-hoc cross-project hack for a tricky issue I don't even remember, but it feels like we should have a proper solution for it instead. Am I wrong? If that is correct, I would really like to avoid spreading its use even more.

[phosek]

compiler-rt/CMakeLists.txt

535

I know, I feel the same way, but I think we can remove condition altogether in the subsequent change D118200 since the generator expression serves the same purpose but it's a cleaner solution. I'd just prefer landing this as two separate changes to make sure this doesn't break anything.

compiler-rt/CMakeLists.txt

 if (DEFINED LIBCXXABI_ENABLE_SHARED AND NOT LIBCXXABI_ENABLE_SHARED)
   set(DEFAULT_SANITIZER_USE_STATIC_CXX_ABI ON)
 endif()
 
 option(SANITIZER_USE_STATIC_CXX_ABI
   "Use static libc++abi." ${DEFAULT_SANITIZER_USE_STATIC_CXX_ABI})
 pythonize_bool(SANITIZER_USE_STATIC_CXX_ABI)
 
+set(DEFAULT_SANITIZER_USE_STATIC_TEST_CXX OFF)
+if (DEFINED LIBCXX_ENABLE_SHARED AND NOT LIBCXX_ENABLE_SHARED)
+  set(DEFAULT_SANITIZER_USE_STATIC_TEST_CXX ON)
+endif()
+
+option(SANITIZER_USE_STATIC_TEST_CXX
+  "Use static libc++ for tests." ${DEFAULT_SANITIZER_USE_STATIC_TEST_CXX})
+pythonize_bool(SANITIZER_USE_STATIC_TEST_CXX)
+
 set(DEFAULT_COMPILER_RT_USE_BUILTINS_LIBRARY OFF)
 if (FUCHSIA)
   set(DEFAULT_COMPILER_RT_USE_BUILTINS_LIBRARY ON)
 endif()
 
 option(COMPILER_RT_USE_BUILTINS_LIBRARY
   "Use compiler-rt builtins instead of libgcc" ${DEFAULT_COMPILER_RT_USE_BUILTINS_LIBRARY})
 
if (SANITIZER_CXX_ABI_LIBNAME STREQUAL "libc++")
   append_libcxx_libs(SANITIZER_CXX_ABI)
 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++")
-  append_libcxx_libs(SANITIZER_TEST_CXX)
+  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)
+    endif()
+  else()
+    append_list_if(COMPILER_RT_HAS_LIBCXX c++ SANITIZER_TEST_CXX_LIBRARIES)
+  endif()
 elseif (SANITIZER_TEST_CXX_LIBNAME STREQUAL "libstdc++")
   append_list_if(COMPILER_RT_HAS_LIBSTDCXX stdc++ 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.