Source/cmake_compiler.cmake

#  SPDX-License-Identifier: Apache-2.0
#  ----------------------------------------------------------------------------
#  Copyright 2020-2025 Arm Limited
#
#  Licensed under the Apache License, Version 2.0 (the "License"); you may not
#  use this file except in compliance with the License. You may obtain a copy
#  of the License at:
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#  License for the specific language governing permissions and limitations
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#  ----------------------------------------------------------------------------

# On CMake 3.25 or older CXX_COMPILER_FRONTEND_VARIANT is not always set
if(CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "")
    set(CMAKE_CXX_COMPILER_FRONTEND_VARIANT "${CMAKE_CXX_COMPILER_ID}")
endif()

# Compiler accepts MSVC-style command line options
set(is_msvc_fe "$<STREQUAL:${CMAKE_CXX_COMPILER_FRONTEND_VARIANT},MSVC>")
# Compiler accepts GNU-style command line options
set(is_gnu_fe1 "$<STREQUAL:${CMAKE_CXX_COMPILER_FRONTEND_VARIANT},GNU>")
# Compiler accepts AppleClang-style command line options, which is also GNU-style
set(is_gnu_fe2 "$<STREQUAL:${CMAKE_CXX_COMPILER_FRONTEND_VARIANT},AppleClang>")
# Compiler accepts GNU-style command line options
set(is_gnu_fe "$<OR:${is_gnu_fe1},${is_gnu_fe2}>")

# Compiler is Visual Studio cl.exe
set(is_msvccl "$<AND:${is_msvc_fe},$<CXX_COMPILER_ID:MSVC>>")
# Compiler is Visual Studio clangcl.exe
set(is_clangcl "$<AND:${is_msvc_fe},$<CXX_COMPILER_ID:Clang>>")
# Compiler is upstream clang with the standard frontend
set(is_clang "$<AND:${is_gnu_fe},$<CXX_COMPILER_ID:Clang,AppleClang>>")