CMake/Modules/CMakeDetermineCXXCompiler.c...

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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_CXX_COMPILER before
# loading this file to force a compiler.
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# use environment variable CXX first if defined by user, next use
# the cmake variable CMAKE_GENERATOR_CXX 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
2007-05-17 21:20:44 +04:00
# as prefix for the tools (e.g. arm-elf-g++, arm-elf-ar etc.)
#
# Sets the following variables:
# CMAKE_CXX_COMPILER
# CMAKE_COMPILER_IS_GNUCXX
# CMAKE_AR
# CMAKE_RANLIB
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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#
# 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}-CXX OPTIONAL)
if(NOT CMAKE_CXX_COMPILER_NAMES)
set(CMAKE_CXX_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(NOT CMAKE_CXX_COMPILER)
set(CMAKE_CXX_COMPILER_INIT NOTFOUND)
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# prefer the environment variable CXX
if($ENV{CXX} MATCHES ".+")
get_filename_component(CMAKE_CXX_COMPILER_INIT $ENV{CXX} PROGRAM PROGRAM_ARGS CMAKE_CXX_FLAGS_ENV_INIT)
if(CMAKE_CXX_FLAGS_ENV_INIT)
set(CMAKE_CXX_COMPILER_ARG1 "${CMAKE_CXX_FLAGS_ENV_INIT}" CACHE STRING "First argument to CXX compiler")
endif()
if(NOT EXISTS ${CMAKE_CXX_COMPILER_INIT})
message(FATAL_ERROR "Could not find compiler set in environment variable CXX:\n$ENV{CXX}.\n${CMAKE_CXX_COMPILER_INIT}")
endif()
endif()
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# next prefer the generator specified compiler
if(CMAKE_GENERATOR_CXX)
if(NOT CMAKE_CXX_COMPILER_INIT)
set(CMAKE_CXX_COMPILER_INIT ${CMAKE_GENERATOR_CXX})
endif()
endif()
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# finally list compilers to try
if(NOT CMAKE_CXX_COMPILER_INIT)
set(CMAKE_CXX_COMPILER_LIST CC ${_CMAKE_TOOLCHAIN_PREFIX}c++ ${_CMAKE_TOOLCHAIN_PREFIX}g++ aCC cl bcc xlC clang++)
endif()
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_cmake_find_compiler(CXX)
else()
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
2007-05-17 21:20:44 +04:00
# we only get here if CMAKE_CXX_COMPILER was specified using -D or a pre-made CMakeCache.txt
# (e.g. via ctest) or set in CMAKE_TOOLCHAIN_FILE
#
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# if CMAKE_CXX_COMPILER is a list of length 2, use the first item as
# CMAKE_CXX_COMPILER and the 2nd one as CMAKE_CXX_COMPILER_ARG1
list(LENGTH CMAKE_CXX_COMPILER _CMAKE_CXX_COMPILER_LIST_LENGTH)
if("${_CMAKE_CXX_COMPILER_LIST_LENGTH}" EQUAL 2)
list(GET CMAKE_CXX_COMPILER 1 CMAKE_CXX_COMPILER_ARG1)
list(GET CMAKE_CXX_COMPILER 0 CMAKE_CXX_COMPILER)
endif()
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# if a compiler was specified by the user but without path,
# now try to find it with the full path
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# if it is found, force it into the cache,
# if not, don't overwrite the setting (which was given by the user) with "NOTFOUND"
# if the CXX compiler already had a path, reuse it for searching the C compiler
get_filename_component(_CMAKE_USER_CXX_COMPILER_PATH "${CMAKE_CXX_COMPILER}" PATH)
if(NOT _CMAKE_USER_CXX_COMPILER_PATH)
find_program(CMAKE_CXX_COMPILER_WITH_PATH NAMES ${CMAKE_CXX_COMPILER})
mark_as_advanced(CMAKE_CXX_COMPILER_WITH_PATH)
if(CMAKE_CXX_COMPILER_WITH_PATH)
set(CMAKE_CXX_COMPILER ${CMAKE_CXX_COMPILER_WITH_PATH} CACHE STRING "CXX compiler" FORCE)
endif()
endif()
endif()
mark_as_advanced(CMAKE_CXX_COMPILER)
if (NOT _CMAKE_TOOLCHAIN_LOCATION)
get_filename_component(_CMAKE_TOOLCHAIN_LOCATION "${CMAKE_CXX_COMPILER}" PATH)
endif ()
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
2007-05-17 21:20:44 +04:00
# This block was used before the compiler was identified by building a
# source file. Unless g++ crashes when building a small C++
# executable this should no longer be needed.
#
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# The g++ that comes with BeOS 5 segfaults if you run "g++ -E"
# ("gcc -E" is fine), which throws up a system dialog box that hangs cmake
# until the user clicks "OK"...so for now, we just assume it's g++.
# if(BEOS)
# set(CMAKE_COMPILER_IS_GNUCXX 1)
# set(CMAKE_COMPILER_IS_GNUCXX_RUN 1)
# endif()
# Build a small source file to identify the compiler.
if(${CMAKE_GENERATOR} MATCHES "Visual Studio")
set(CMAKE_CXX_COMPILER_ID_RUN 1)
set(CMAKE_CXX_PLATFORM_ID "Windows")
set(CMAKE_CXX_COMPILER_ID "MSVC")
endif()
if(NOT CMAKE_CXX_COMPILER_ID_RUN)
set(CMAKE_CXX_COMPILER_ID_RUN 1)
# 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_CXX_COMPILER_ID_TEST_FLAGS
# Try compiling to an object file only.
"-c"
)
# Try to identify the compiler.
set(CMAKE_CXX_COMPILER_ID)
file(READ ${CMAKE_ROOT}/Modules/CMakePlatformId.h.in
CMAKE_CXX_COMPILER_ID_PLATFORM_CONTENT)
include(${CMAKE_ROOT}/Modules/CMakeDetermineCompilerId.cmake)
CMAKE_DETERMINE_COMPILER_ID(CXX CXXFLAGS CMakeCXXCompilerId.cpp)
# Set old compiler and platform id variables.
if("${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU")
set(CMAKE_COMPILER_IS_GNUCXX 1)
endif()
if("${CMAKE_CXX_PLATFORM_ID}" MATCHES "MinGW")
set(CMAKE_COMPILER_IS_MINGW 1)
elseif("${CMAKE_CXX_PLATFORM_ID}" MATCHES "Cygwin")
set(CMAKE_COMPILER_IS_CYGWIN 1)
endif()
endif()
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# if we have a g++ cross compiler, they have usually some prefix, like
# e.g. powerpc-linux-g++, arm-elf-g++ or i586-mingw32msvc-g++ , optionally
# with a 3-component version number at the end (e.g. arm-eabi-gcc-4.5.2).
# The other tools of the toolchain usually have the same prefix
# NAME_WE cannot be used since then this test will fail for names lile
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# "arm-unknown-nto-qnx6.3.0-gcc.exe", where BASENAME would be
# "arm-unknown-nto-qnx6" instead of the correct "arm-unknown-nto-qnx6.3.0-"
if (CMAKE_CROSSCOMPILING
AND "${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU"
AND NOT _CMAKE_TOOLCHAIN_PREFIX)
get_filename_component(COMPILER_BASENAME "${CMAKE_CXX_COMPILER}" NAME)
if (COMPILER_BASENAME MATCHES "^(.+-)[gc]\\+\\+(-[0-9]+\\.[0-9]+\\.[0-9]+)?(\\.exe)?$")
set(_CMAKE_TOOLCHAIN_PREFIX ${CMAKE_MATCH_1})
endif ()
# if "llvm-" is part of the prefix, remove it, since llvm doesn't have its own binutils
# but uses the regular ar, objcopy, etc. (instead of llvm-objcopy etc.)
if ("${_CMAKE_TOOLCHAIN_PREFIX}" MATCHES "(.+-)?llvm-$")
set(_CMAKE_TOOLCHAIN_PREFIX ${CMAKE_MATCH_1})
endif ()
endif (CMAKE_CROSSCOMPILING
AND "${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU"
AND NOT _CMAKE_TOOLCHAIN_PREFIX)
include(${CMAKE_ROOT}/Modules/CMakeClDeps.cmake)
include(CMakeFindBinUtils)
if(MSVC_CXX_ARCHITECTURE_ID)
set(SET_MSVC_CXX_ARCHITECTURE_ID
"set(MSVC_CXX_ARCHITECTURE_ID ${MSVC_CXX_ARCHITECTURE_ID})")
endif()
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# configure all variables set in this file
configure_file(${CMAKE_ROOT}/Modules/CMakeCXXCompiler.cmake.in
${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeCXXCompiler.cmake
@ONLY IMMEDIATE # IMMEDIATE must be here for compatibility mode <= 2.0
)
set(CMAKE_CXX_COMPILER_ENV_VAR "CXX")