[xray][tests][RHDTS] Add -lstdc++ after LLVM libs, resolving link error with RHDTS

[hubert.reinterpretcast]

Summary

A link error was encountered when using the Red Hat Developer Toolset. In the RHDTS, libstdc++.so is a linker script that may resolve symbols to a static library. This patch places -lstdc++ later in the ordering.

[tstellar]

lib/xray/tests/CMakeLists.txt

83

Any idea why the xray tests need to manually specify the standard library like this instead of letting the compiler driver do it automatically?

[hubert.reinterpretcast]

lib/xray/tests/CMakeLists.txt

83

It uses the C compiler invocation for the linking, perhaps to avoid picking up the default C++ run-time libraries.

[dberris]

LGTM

lib/xray/tests/CMakeLists.txt

83

That's a good question @tstellar -- a lot of this is cargo-cult copy-pasted from other sanitizer tests. The reason I think is because there are sanitized builds of the standard library (libc++ at least) and this allows us to pick those as well (say if we're building an address-sanitized XRay implementation).

lib/xray/tests/CMakeLists.txt

function(get_xray_lib_for_arch arch lib)
   else()
     set(tgt_name "RTXRay.test.${arch}")
   endif()
   set(${lib} "${tgt_name}" PARENT_SCOPE)
 endfunction()
 
 set(XRAY_TEST_ARCH ${XRAY_SUPPORTED_ARCH})
 set(XRAY_UNITTEST_LINK_FLAGS
-  ${CMAKE_THREAD_LIBS_INIT}
-  -l${SANITIZER_CXX_ABI_LIBRARY})
+  ${CMAKE_THREAD_LIBS_INIT})
 
 if (NOT APPLE)
   # Needed by LLVMSupport.
   append_list_if(
     COMPILER_RT_HAS_TERMINFO
     -l${COMPILER_RT_TERMINFO_LIB} XRAY_UNITTEST_LINK_FLAGS)
 
   if (COMPILER_RT_STANDALONE_BUILD)
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()
 
+list(APPEND XRAY_UNITTEST_LINK_FLAGS -l${SANITIZER_CXX_ABI_LIBRARY})
+
 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