Commit b6d3a1c0 authored by Brad King's avatar Brad King

Clang: Diagnose unsupported GNU-like clang targeting MSVC ABI

The LLVM/Clang installer on Windows provides a `LLVM/bin` directory
containing `clang.exe` and `clang++.exe` command-line tools that have a
GNU-like command-line but target the MSVC ABI (instead of MinGW).  We
do not support this combination, so diagnose and reject it explicitly.
Tell users what to do to use the `clang-cl.exe` tool instead.

Issue: #16439
parent a91eb5e4
......@@ -110,6 +110,7 @@ if(NOT CMAKE_C_COMPILER_ID_RUN)
include(${CMAKE_ROOT}/Modules/CMakeDetermineCompilerId.cmake)
CMAKE_DETERMINE_COMPILER_ID(C CFLAGS CMakeCCompilerId.c)
CMAKE_DIAGNOSE_UNSUPPORTED_CLANG(C CC)
# Set old compiler and platform id variables.
if(CMAKE_C_COMPILER_ID STREQUAL "GNU")
......
......@@ -105,6 +105,7 @@ if(NOT CMAKE_CXX_COMPILER_ID_RUN)
include(${CMAKE_ROOT}/Modules/CMakeDetermineCompilerId.cmake)
CMAKE_DETERMINE_COMPILER_ID(CXX CXXFLAGS CMakeCXXCompilerId.cpp)
CMAKE_DIAGNOSE_UNSUPPORTED_CLANG(CXX CXX)
# Set old compiler and platform id variables.
if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
......
......@@ -735,3 +735,38 @@ function(CMAKE_DETERMINE_MSVC_SHOWINCLUDES_PREFIX lang userflags)
set(CMAKE_${lang}_CL_SHOWINCLUDES_PREFIX "" PARENT_SCOPE)
endif()
endfunction()
function(CMAKE_DIAGNOSE_UNSUPPORTED_CLANG lang envvar)
if(NOT CMAKE_HOST_WIN32 OR CMAKE_GENERATOR MATCHES "Visual Studio" OR
NOT "${CMAKE_${lang}_COMPILER_ID};${CMAKE_${lang}_SIMULATE_ID}" STREQUAL "Clang;MSVC")
return()
endif()
# Test whether a GNU-like command-line option works.
execute_process(COMMAND "${CMAKE_${lang}_COMPILER}" --version
RESULT_VARIABLE _clang_result
OUTPUT_VARIABLE _clang_stdout
ERROR_VARIABLE _clang_stderr)
if(NOT _clang_result EQUAL 0)
return()
endif()
# Help the user configure the environment to use the MSVC-like Clang.
string(CONCAT _msg
"The Clang compiler tool\n"
" \"${CMAKE_${lang}_COMPILER}\"\n"
"targets the MSVC ABI but has a GNU-like command-line interface. "
"This is not supported. "
"Use 'clang-cl' instead, e.g. by setting '${envvar}=clang-cl' in the environment."
)
execute_process(COMMAND rc -help
RESULT_VARIABLE _rc_result
OUTPUT_VARIABLE _rc_stdout
ERROR_VARIABLE _rc_stderr)
if(NOT _rc_result EQUAL 0)
string(APPEND _msg " "
"Furthermore, use the MSVC command-line environment."
)
endif()
message(FATAL_ERROR "${_msg}")
endfunction()
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