[compiler-rt] [MSVC] Detect MSVC as a compiler-id for lit. (#108255)

This is only for "real" msvc and is to support running sanitizer tests
with "real" MSVC. Most compiler-rt tests do not yet pass with msvc,
which will be addressed in future PRs for asan, sanitizer_common, and
the fuzzer.

We've been using these changes to lit to run CI for the version of
address sanitizer that ships with MSVC, by upstreaming them we can avoid
being broken by future lit changes and allow contributors (importantly
_us_) to run the MSVC tests on changes developed in the open.

Author: barcharcraz

compiler-rt/cmake/base-config-ix.cmake

@@ -81,6 +81,8 @@ if("${COMPILER_RT_TEST_COMPILER}" MATCHES "clang[+]*$")
   set(COMPILER_RT_TEST_COMPILER_ID Clang)
 elseif("${COMPILER_RT_TEST_COMPILER}" MATCHES "clang.*.exe$")
   set(COMPILER_RT_TEST_COMPILER_ID Clang)
+elseif("${COMPILER_RT_TEST_COMPILER}" MATCHES "cl.exe$")
+  set(COMPILER_RT_TEST_COMPILER_ID MSVC)
 else()
   set(COMPILER_RT_TEST_COMPILER_ID GNU)
 endif()

compiler-rt/test/lit.common.cfg.py

@@ -148,6 +148,9 @@ def push_dynamic_library_lookup_path(config, new_path):
         # requested it because it makes ASan reports more precise.
         config.debug_info_flags.append("-gcodeview")
         config.debug_info_flags.append("-gcolumn-info")
+elif compiler_id == "MSVC":
+    config.debug_info_flags = ["/Z7"]
+    config.cxx_mode_flags = []
 elif compiler_id == "GNU":
     config.cxx_mode_flags = ["-x c++"]
     config.debug_info_flags = ["-g"]