[CMake] [Darwin] Log architecture test failures to CMakeError.log

This makes debugging configuration issues way easier.

llvm-svn: 255183

diff --git a/compiler-rt/cmake/Modules/CompilerRTDarwinUtils.cmake b/compiler-rt/cmake/Modules/CompilerRTDarwinUtils.cmake
index b304df2..511361b 100644 (file)
--- a/compiler-rt/cmake/Modules/CompilerRTDarwinUtils.cmake
+++ b/compiler-rt/cmake/Modules/CompilerRTDarwinUtils.cmake
@@ -78,6 +78,10 @@ function(darwin_test_archs os valid_archs)
                 OUTPUT_VARIABLE TEST_OUTPUT)
     if(${CAN_TARGET_${os}_${arch}})
       list(APPEND working_archs ${arch})
+    else()
+      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
+        "Testing compiler for supporting ${os}-${arch}:\n"
+        "${TEST_OUTPUT}\n")
     endif()
   endforeach()
   set(${valid_archs} ${working_archs}