Merge topic 'FindOpenMP-clang-windows' into release-3.29

3adeb3b470 ci: Enable FindOpenMP tests in LLVM/Clang nightly CI jobs on Windows
3019af64c2 FindOpenMP: Add support for GNU-like Clang targeting MSVC ABI

Acked-by: Kitware Robot <[email protected]>
Merge-request: !9235

.gitlab/ci/configure_windows_clang_common.cmake

@@ -1,3 +1,7 @@
+set(CMake_TEST_FindOpenMP "ON" CACHE BOOL "")
+set(CMake_TEST_FindOpenMP_C "ON" CACHE BOOL "")
+set(CMake_TEST_FindOpenMP_CXX "ON" CACHE BOOL "")
+set(CMake_TEST_FindOpenMP_Fortran "OFF" CACHE BOOL "")
 set(CMake_TEST_Java OFF CACHE BOOL "")
 
 set(configure_no_sccache 1)

Modules/FindOpenMP.cmake

@@ -224,7 +224,8 @@ function(_OPENMP_GET_FLAGS LANG FLAG_MODE OPENMP_FLAG_VAR OPENMP_LIB_NAMES_VAR)
       OUTPUT_VARIABLE OpenMP_TRY_COMPILE_OUTPUT
     )
 
-    if(OpenMP_COMPILE_RESULT_${FLAG_MODE}_${OPENMP_PLAIN_FLAG})
+    if(OpenMP_COMPILE_RESULT_${FLAG_MODE}_${OPENMP_PLAIN_FLAG} AND
+       NOT "x${CMAKE_${LANG}_SIMULATE_ID}" STREQUAL "xMSVC")
       set("${OPENMP_FLAG_VAR}" "${OPENMP_FLAG}" PARENT_SCOPE)
 
       if(CMAKE_${LANG}_VERBOSE_FLAG)