[CMake] [MinGW] Enable use of LLVM_USE_SANITIZER in a MinGW environment

[zero9178]

Summary

Currently using LLVM_USE_SANITIZER with a MinGW target leads to a fatal configuration error due to an unsupported platform. MinGW targets on clang however implement a few sanitizers, currently ASAN and UBSAN.

This patch enables LLVM_USE_SANITIZER in a MinGW environment as well.

If accepted I'd need this patch to be committed for me with the email: [e-mail]

[mstorsjo]

I guess this looks sensible to me, although I'm a bit unsure why we need to hardcode exactly which sets of sanitizers each target environment supports at the moment. I would kinda understand if we want to keep MSVC separate if those cases used different command line options, but it looks like they don't, so technically one could kinda merge all of the existing unix/msvc cases too. If one would try to use a sanitizer that isn't supported, the cmake configuration wouldn't error out immediately, but it'd be noticed directly when the compiler errors out on the unsupported options anyway.

What does @rnk think about it?

[thieta]

I can see it both ways - I like when CMake tells me if a configuration is not supported - but on the other hand this is probably a pretty easy to spot in the compiler error what's wrong. I guess the section could be replaced with actually trying to compile a snippet with TryCompile with the sanitizer flag instead and replace the specific flag check.

[mstorsjo]

@rnk - what's your opinion on this?

[rnk]

lgtm

llvm/cmake/modules/HandleLLVMOptions.cmake

803–804

Well, I guess there is prior art for this tortured conditional.

811

MSVC should probably get the same treatment, but that doesn't need to be part of this change.

llvm/cmake/modules/HandleLLVMOptions.cmake

elseif (LLVM_USE_SANITIZER STREQUAL "Address;Undefined" OR
       append("-fsanitize=address" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
       append("${LLVM_UBSAN_FLAGS}" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
     elseif (LLVM_USE_SANITIZER STREQUAL "Leaks")
       append_common_sanitizer_flags()
       append("-fsanitize=leak" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
     else()
       message(FATAL_ERROR "Unsupported value of LLVM_USE_SANITIZER: ${LLVM_USE_SANITIZER}")
     endif()
+  elseif(MINGW)
+    if (LLVM_USE_SANITIZER STREQUAL "Address")
+      append_common_sanitizer_flags()
+      append("-fsanitize=address" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+    elseif (LLVM_USE_SANITIZER STREQUAL "Undefined")
+      append_common_sanitizer_flags()
+      append("${LLVM_UBSAN_FLAGS}" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+    elseif (LLVM_USE_SANITIZER STREQUAL "Address;Undefined" OR
+            LLVM_USE_SANITIZER STREQUAL "Undefined;Address")
+      append_common_sanitizer_flags()
+      append("-fsanitize=address" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+      append("${LLVM_UBSAN_FLAGS}" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+    else()
+      message(FATAL_ERROR "This sanitizer not yet supported in a MinGW environment: ${LLVM_USE_SANITIZER}")
+    endif()
   elseif(MSVC)
     if (LLVM_USE_SANITIZER STREQUAL "Address")
       append_common_sanitizer_flags()
       append("-fsanitize=address" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
     else()
       message(FATAL_ERROR "This sanitizer not yet supported in the MSVC environment: ${LLVM_USE_SANITIZER}")
     endif()
   else()
     message(FATAL_ERROR "LLVM_USE_SANITIZER is not supported on this platform.")