CMake/Modules/CMakeDetermineCCompiler.cmake

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#=============================================================================
# Copyright 2002-2009 Kitware, Inc.
#
# Distributed under the OSI-approved BSD License (the "License");
# see accompanying file Copyright.txt for details.
#
# This software is distributed WITHOUT ANY WARRANTY; without even the
# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the License for more information.
#=============================================================================
# (To distribute this file outside of CMake, substitute the full
# License text for the above reference.)
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# determine the compiler to use for C programs
# NOTE, a generator may set CMAKE_C_COMPILER before
# loading this file to force a compiler.
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# use environment variable CC first if defined by user, next use
# the cmake variable CMAKE_GENERATOR_CC which can be defined by a generator
# as a default compiler
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# If the internal cmake variable _CMAKE_TOOLCHAIN_PREFIX is set, this is used
ENH: merge CMake-CrossCompileBasic to HEAD -add a RESULT_VARIABLE to INCLUDE() -add CMAKE_TOOLCHAIN_FILE for specifiying your (potentially crosscompiling) toolchain -have TRY_RUN() complain if you try to use it in crosscompiling mode (which were compiled but cannot run on this system) -use CMAKE_EXECUTABLE_SUFFIX in TRY_RUN(), probably TRY_RUN won't be able to run the executables if they have a different suffix because they are probably crosscompiled, but nevertheless it should be able to find them -make several cmake variables presettable by the user: CMAKE_C/CXX_COMPILER, CMAKE_C/CXX_OUTPUT_EXTENSION, CMAKE_SYSTEM_NAME, CMAKE_SYSTEM_INFO_FILE -support prefix for GNU toolchains (arm-elf-gcc, arm-elf-ar, arm-elf-strip etc.) -move ranlib on OSX from the file command to a command in executed in cmake_install.cmake -add support for stripping during install in cmake_install.cmake -split out cl.cmake from Windows-cl.cmake, first (very incomplete) step to support MS crosscompiling tools -remove stdio.h from the simple C program which checks if the compiler works, since this may not exist for some embedded platforms -create a new CMakeFindBinUtils.cmake which collects the search fro ar, ranlib, strip, ld, link, install_name_tool and other tools like these -add support for CMAKE_FIND_ROOT_PATH for all FIND_XXX commands, which is a list of directories which will be prepended to all search directories, right now as a cmake variable, turning it into a global cmake property may need some more work -remove cmTestTestHandler::TryExecutable(), it's unused -split cmFileCommand::HandleInstall() into slightly smaller functions Alex
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# as prefix for the tools (e.g. arm-elf-gcc, arm-elf-ar etc.). This works
# currently with the GNU crosscompilers.
#
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# Sets the following variables:
ENH: merge CMake-CrossCompileBasic to HEAD -add a RESULT_VARIABLE to INCLUDE() -add CMAKE_TOOLCHAIN_FILE for specifiying your (potentially crosscompiling) toolchain -have TRY_RUN() complain if you try to use it in crosscompiling mode (which were compiled but cannot run on this system) -use CMAKE_EXECUTABLE_SUFFIX in TRY_RUN(), probably TRY_RUN won't be able to run the executables if they have a different suffix because they are probably crosscompiled, but nevertheless it should be able to find them -make several cmake variables presettable by the user: CMAKE_C/CXX_COMPILER, CMAKE_C/CXX_OUTPUT_EXTENSION, CMAKE_SYSTEM_NAME, CMAKE_SYSTEM_INFO_FILE -support prefix for GNU toolchains (arm-elf-gcc, arm-elf-ar, arm-elf-strip etc.) -move ranlib on OSX from the file command to a command in executed in cmake_install.cmake -add support for stripping during install in cmake_install.cmake -split out cl.cmake from Windows-cl.cmake, first (very incomplete) step to support MS crosscompiling tools -remove stdio.h from the simple C program which checks if the compiler works, since this may not exist for some embedded platforms -create a new CMakeFindBinUtils.cmake which collects the search fro ar, ranlib, strip, ld, link, install_name_tool and other tools like these -add support for CMAKE_FIND_ROOT_PATH for all FIND_XXX commands, which is a list of directories which will be prepended to all search directories, right now as a cmake variable, turning it into a global cmake property may need some more work -remove cmTestTestHandler::TryExecutable(), it's unused -split cmFileCommand::HandleInstall() into slightly smaller functions Alex
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# CMAKE_C_COMPILER
# CMAKE_AR
# CMAKE_RANLIB
# CMAKE_COMPILER_IS_GNUCC
#
# If not already set before, it also sets
# _CMAKE_TOOLCHAIN_PREFIX
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include(${CMAKE_ROOT}/Modules/CMakeDetermineCompiler.cmake)
Prefer generic system compilers by default for C, C++, and Fortran Teach CMake to prefer the system default compiler automatically when no compiler is specified. By default use "cc" for C, "CC" for C++, and "f95" for Fortran. Load a new Platform/<os>-<lang>.cmake module to allow each platform to specify for each language its system compiler name(s) and/or exclude certain names. Create Platform/(CYGWIN|Darwin|Linux|Windows)-CXX.cmake modules to specify "c++" as the system C++ compiler name for these platforms. On systems that use case-insensitive filesystems exclude C++ compiler names that are distinguished from C compiler names only by case. This will change the default compiler selection for existing build scripts that do not specify a compiler when run on machines with separate system and GNU compilers both installed in the PATH. We do not make this change in default behavior lightly. However: (1) If a given build really needs specific compilers one should specify them explicitly e.g. by setting CC, CXX, and FC in the environment. (2) The motivating case is to prefer the system Clang on newer OS X systems over the older GNU compilers typically also installed. On such systems the names "cc" and "c++" link to Clang. This is the first platform known to CMake on which "c++" is not a GNU compiler. The old behavior selected "gcc" for C and "c++" C++ and therefore chooses GNU for C and Clang for C++ by default. The new behavior selects GNU or Clang consistently for both languages on older or newer OS X systems, respectively. (3) Other than the motivating OS X case the conditions under which the behavior changes do not tend to exist in default OS installations. They typically occur only on non-GNU systems with manually-installed GNU compilers. (4) The consequences of the new behavior are not dire. At worst the project fails to compile with the system compiler when it previously worked with the non-system GNU compiler. Such failure is easy to work around (see #1). In short this change creates a more sensible default behavior everywhere and fixes poor default behavior on a widely-used platform at the cost of a modest change in behavior in less-common conditions.
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# Load system-specific compiler preferences for this language.
include(Platform/${CMAKE_SYSTEM_NAME}-Determine-C OPTIONAL)
include(Platform/${CMAKE_SYSTEM_NAME}-C OPTIONAL)
if(NOT CMAKE_C_COMPILER_NAMES)
set(CMAKE_C_COMPILER_NAMES cc)
endif()
Prefer generic system compilers by default for C, C++, and Fortran Teach CMake to prefer the system default compiler automatically when no compiler is specified. By default use "cc" for C, "CC" for C++, and "f95" for Fortran. Load a new Platform/<os>-<lang>.cmake module to allow each platform to specify for each language its system compiler name(s) and/or exclude certain names. Create Platform/(CYGWIN|Darwin|Linux|Windows)-CXX.cmake modules to specify "c++" as the system C++ compiler name for these platforms. On systems that use case-insensitive filesystems exclude C++ compiler names that are distinguished from C compiler names only by case. This will change the default compiler selection for existing build scripts that do not specify a compiler when run on machines with separate system and GNU compilers both installed in the PATH. We do not make this change in default behavior lightly. However: (1) If a given build really needs specific compilers one should specify them explicitly e.g. by setting CC, CXX, and FC in the environment. (2) The motivating case is to prefer the system Clang on newer OS X systems over the older GNU compilers typically also installed. On such systems the names "cc" and "c++" link to Clang. This is the first platform known to CMake on which "c++" is not a GNU compiler. The old behavior selected "gcc" for C and "c++" C++ and therefore chooses GNU for C and Clang for C++ by default. The new behavior selects GNU or Clang consistently for both languages on older or newer OS X systems, respectively. (3) Other than the motivating OS X case the conditions under which the behavior changes do not tend to exist in default OS installations. They typically occur only on non-GNU systems with manually-installed GNU compilers. (4) The consequences of the new behavior are not dire. At worst the project fails to compile with the system compiler when it previously worked with the non-system GNU compiler. Such failure is easy to work around (see #1). In short this change creates a more sensible default behavior everywhere and fixes poor default behavior on a widely-used platform at the cost of a modest change in behavior in less-common conditions.
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if(${CMAKE_GENERATOR} MATCHES "Visual Studio")
elseif("${CMAKE_GENERATOR}" MATCHES "Xcode")
set(CMAKE_C_COMPILER_XCODE_TYPE sourcecode.c.c)
_cmake_find_compiler_path(C)
else()
if(NOT CMAKE_C_COMPILER)
set(CMAKE_C_COMPILER_INIT NOTFOUND)
# prefer the environment variable CC
if(NOT $ENV{CC} STREQUAL "")
get_filename_component(CMAKE_C_COMPILER_INIT $ENV{CC} PROGRAM PROGRAM_ARGS CMAKE_C_FLAGS_ENV_INIT)
if(CMAKE_C_FLAGS_ENV_INIT)
set(CMAKE_C_COMPILER_ARG1 "${CMAKE_C_FLAGS_ENV_INIT}" CACHE STRING "First argument to C compiler")
endif()
if(NOT EXISTS ${CMAKE_C_COMPILER_INIT})
message(FATAL_ERROR "Could not find compiler set in environment variable CC:\n$ENV{CC}.")
endif()
endif()
# next try prefer the compiler specified by the generator
if(CMAKE_GENERATOR_CC)
if(NOT CMAKE_C_COMPILER_INIT)
set(CMAKE_C_COMPILER_INIT ${CMAKE_GENERATOR_CC})
endif()
endif()
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# finally list compilers to try
if(NOT CMAKE_C_COMPILER_INIT)
set(CMAKE_C_COMPILER_LIST ${_CMAKE_TOOLCHAIN_PREFIX}cc ${_CMAKE_TOOLCHAIN_PREFIX}gcc cl bcc xlc clang)
endif()
_cmake_find_compiler(C)
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else()
_cmake_find_compiler_path(C)
endif()
mark_as_advanced(CMAKE_C_COMPILER)
# Each entry in this list is a set of extra flags to try
# adding to the compile line to see if it helps produce
# a valid identification file.
set(CMAKE_C_COMPILER_ID_TEST_FLAGS_FIRST)
set(CMAKE_C_COMPILER_ID_TEST_FLAGS
# Try compiling to an object file only.
"-c"
# Try enabling ANSI mode on HP.
"-Aa"
# Try compiling K&R-compatible code (needed by Bruce C Compiler).
"-D__CLASSIC_C__"
)
endif()
# Build a small source file to identify the compiler.
if(NOT CMAKE_C_COMPILER_ID_RUN)
set(CMAKE_C_COMPILER_ID_RUN 1)
# Try to identify the compiler.
set(CMAKE_C_COMPILER_ID)
set(CMAKE_C_PLATFORM_ID)
file(READ ${CMAKE_ROOT}/Modules/CMakePlatformId.h.in
CMAKE_C_COMPILER_ID_PLATFORM_CONTENT)
# The IAR compiler produces weird output.
# See https://cmake.org/Bug/view.php?id=10176#c19598
list(APPEND CMAKE_C_COMPILER_ID_VENDORS IAR)
set(CMAKE_C_COMPILER_ID_VENDOR_FLAGS_IAR )
set(CMAKE_C_COMPILER_ID_VENDOR_REGEX_IAR "IAR .+ Compiler")
# Match the link line from xcodebuild output of the form
# Ld ...
# ...
# /path/to/cc ...CompilerIdC/...
# to extract the compiler front-end for the language.
set(CMAKE_C_COMPILER_ID_TOOL_MATCH_REGEX "\nLd[^\n]*(\n[ \t]+[^\n]*)*\n[ \t]+([^ \t\r\n]+)[^\r\n]*-o[^\r\n]*CompilerIdC/(\\./)?(CompilerIdC.xctest/)?CompilerIdC[ \t\n\\\"]")
set(CMAKE_C_COMPILER_ID_TOOL_MATCH_INDEX 2)
include(${CMAKE_ROOT}/Modules/CMakeDetermineCompilerId.cmake)
CMAKE_DETERMINE_COMPILER_ID(C CFLAGS CMakeCCompilerId.c)
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# Set old compiler and platform id variables.
if(CMAKE_C_COMPILER_ID STREQUAL "GNU")
set(CMAKE_COMPILER_IS_GNUCC 1)
endif()
if(CMAKE_C_PLATFORM_ID MATCHES "MinGW")
set(CMAKE_COMPILER_IS_MINGW 1)
elseif(CMAKE_C_PLATFORM_ID MATCHES "Cygwin")
set(CMAKE_COMPILER_IS_CYGWIN 1)
endif()
endif()
if (NOT _CMAKE_TOOLCHAIN_LOCATION)
get_filename_component(_CMAKE_TOOLCHAIN_LOCATION "${CMAKE_C_COMPILER}" PATH)
endif ()
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# If we have a gcc cross compiler, they have usually some prefix, like
# e.g. powerpc-linux-gcc, arm-elf-gcc or i586-mingw32msvc-gcc, optionally
# with a 3-component version number at the end (e.g. arm-eabi-gcc-4.5.2).
# The other tools of the toolchain usually have the same prefix
# NAME_WE cannot be used since then this test will fail for names like
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# "arm-unknown-nto-qnx6.3.0-gcc.exe", where BASENAME would be
# "arm-unknown-nto-qnx6" instead of the correct "arm-unknown-nto-qnx6.3.0-"
if (CMAKE_CROSSCOMPILING AND NOT _CMAKE_TOOLCHAIN_PREFIX)
if(CMAKE_C_COMPILER_ID MATCHES "GNU" OR CMAKE_C_COMPILER_ID MATCHES "Clang")
get_filename_component(COMPILER_BASENAME "${CMAKE_C_COMPILER}" NAME)
if (COMPILER_BASENAME MATCHES "^(.+-)(clang|g?cc)(-[0-9]+\\.[0-9]+\\.[0-9]+)?(\\.exe)?$")
set(_CMAKE_TOOLCHAIN_PREFIX ${CMAKE_MATCH_1})
elseif(CMAKE_C_COMPILER_ID MATCHES "Clang")
if(CMAKE_C_COMPILER_TARGET)
set(_CMAKE_TOOLCHAIN_PREFIX ${CMAKE_C_COMPILER_TARGET}-)
endif()
elseif(COMPILER_BASENAME MATCHES "qcc(\\.exe)?$")
if(CMAKE_C_COMPILER_TARGET MATCHES "gcc_nto([^_le]+)(le)?")
set(_CMAKE_TOOLCHAIN_PREFIX nto${CMAKE_MATCH_1}-)
endif()
endif ()
# if "llvm-" is part of the prefix, remove it, since llvm doesn't have its own binutils
# but uses the regular ar, objcopy, etc. (instead of llvm-objcopy etc.)
if ("${_CMAKE_TOOLCHAIN_PREFIX}" MATCHES "(.+-)?llvm-$")
set(_CMAKE_TOOLCHAIN_PREFIX ${CMAKE_MATCH_1})
endif ()
elseif(CMAKE_C_COMPILER_ID MATCHES "TI")
# TI compilers are named e.g. cl6x, cl470 or armcl.exe
get_filename_component(COMPILER_BASENAME "${CMAKE_C_COMPILER}" NAME)
if (COMPILER_BASENAME MATCHES "^(.+)?cl([^.]+)?(\\.exe)?$")
set(_CMAKE_TOOLCHAIN_PREFIX "${CMAKE_MATCH_1}")
set(_CMAKE_TOOLCHAIN_SUFFIX "${CMAKE_MATCH_2}")
endif ()
endif()
endif ()
include(CMakeFindBinUtils)
if(MSVC_C_ARCHITECTURE_ID)
set(SET_MSVC_C_ARCHITECTURE_ID
"set(MSVC_C_ARCHITECTURE_ID ${MSVC_C_ARCHITECTURE_ID})")
endif()
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# configure variables set in this file for fast reload later on
configure_file(${CMAKE_ROOT}/Modules/CMakeCCompiler.cmake.in
Make platform information files specific to the CMake version At the top of a build tree we configure inside the CMakeFiles directory files such as "CMakeSystem.cmake" and "CMake<lang>Compiler.cmake" to save information detected about the system and compilers in use. The method of detection and the exact results store varies across CMake versions as things improve. This leads to problems when loading files configured by a different version of CMake. Previously we ignored such existing files only if the major.minor part of the CMake version component changed, and depended on the CMakeCache.txt to tell us the last version of CMake that wrote the files. This led to problems if the user deletes the CMakeCache.txt or we add required information to the files in a patch-level release of CMake (still a "feature point" release by modern CMake versioning convention). Ensure that we always have version-consistent platform information files by storing them in a subdirectory named with the CMake version. Every version of CMake will do its own system and compiler identification checks even when a build tree has already been configured by another version of CMake. Stored results will not clobber those from other versions of CMake which may be run again on the same tree in the future. Loaded results will match what the system and language modules expect. Rename the undocumented variable CMAKE_PLATFORM_ROOT_BIN to CMAKE_PLATFORM_INFO_DIR to clarify its purpose. The new variable points at the version-specific directory while the old variable did not.
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${CMAKE_PLATFORM_INFO_DIR}/CMakeCCompiler.cmake
@ONLY
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)
set(CMAKE_C_COMPILER_ENV_VAR "CC")