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|
#.rst:
# WriteCompilerDetectionHeader
# ----------------------------
#
# This module provides the function write_compiler_detection_header().
#
# The ``WRITE_COMPILER_DETECTION_HEADER`` function can be used to generate
# a file suitable for preprocessor inclusion which contains macros to be
# used in source code::
#
# write_compiler_detection_header(
# FILE <file>
# PREFIX <prefix>
# COMPILERS <compiler> [...]
# FEATURES <feature> [...]
# [VERSION <version>]
# [PROLOG <prolog>]
# [EPILOG <epilog>]
# )
#
# The ``write_compiler_detection_header`` function generates the
# file ``<file>`` with macros which all have the prefix ``<prefix>``.
#
# ``VERSION`` may be used to specify the API version to be generated.
# Future versions of CMake may introduce alternative APIs. A given
# API is selected by any ``<version>`` value greater than or equal
# to the version of CMake that introduced the given API and less
# than the version of CMake that introduced its succeeding API.
# The value of the :variable:`CMAKE_MINIMUM_REQUIRED_VERSION`
# variable is used if no explicit version is specified.
# (As of CMake version |release| there is only one API version.)
#
# ``PROLOG`` may be specified as text content to write at the start of the
# header. ``EPILOG`` may be specified as text content to write at the end
# of the header
#
# At least one ``<compiler>`` and one ``<feature>`` must be listed. Compilers
# which are known to CMake, but not specified are detected and a preprocessor
# ``#error`` is generated for them. A preprocessor macro matching
# ``<PREFIX>_COMPILER_IS_<compiler>`` is generated for each compiler
# known to CMake to contain the value ``0`` or ``1``.
#
# Possible compiler identifiers are documented with the
# :variable:`CMAKE_<LANG>_COMPILER_ID` variable.
# Available features in this version of CMake are listed in the
# :prop_gbl:`CMAKE_C_KNOWN_FEATURES` and
# :prop_gbl:`CMAKE_CXX_KNOWN_FEATURES` global properties.
#
# Feature Test Macros
# ===================
#
# For each compiler, a preprocessor test of the compiler version is generated
# denoting whether each feature is enabled. A preprocessor macro
# matching ``<PREFIX>_COMPILER_<FEATURE>``, where ``<FEATURE>`` is the
# upper-case ``<feature>`` name, is generated to contain the value
# ``0`` or ``1`` depending on whether the compiler in use supports the
# feature:
#
# .. code-block:: cmake
#
# write_compiler_detection_header(
# FILE climbingstats_compiler_detection.h
# PREFIX ClimbingStats
# COMPILERS GNU Clang MSVC
# FEATURES cxx_variadic_templates
# )
#
# .. code-block:: c++
#
# #if ClimbingStats_COMPILER_CXX_VARIADIC_TEMPLATES
# template<typename... T>
# void someInterface(T t...) { /* ... */ }
# #else
# // Compatibility versions
# template<typename T1>
# void someInterface(T1 t1) { /* ... */ }
# template<typename T1, typename T2>
# void someInterface(T1 t1, T2 t2) { /* ... */ }
# template<typename T1, typename T2, typename T3>
# void someInterface(T1 t1, T2 t2, T3 t3) { /* ... */ }
# #endif
#
# Symbol Macros
# =============
#
# Some additional symbol-defines are created for particular features for
# use as symbols which may be conditionally defined empty:
#
# .. code-block:: c++
#
# class MyClass ClimbingStats_DECL_CXX_FINAL
# {
# ClimbingStats_DECL_CXX_CONSTEXPR int someInterface() { return 42; }
# };
#
# The ``ClimbingStats_DECL_CXX_FINAL`` macro will expand to ``final`` if the
# compiler (and its flags) support the ``cxx_final`` feature, and the
# ``ClimbingStats_DECL_CXX_CONSTEXPR`` macro will expand to ``constexpr``
# if ``cxx_constexpr`` is supported.
#
# The following features generate corresponding symbol defines:
#
# ========================== =================================== =================
# Feature Define Symbol
# ========================== =================================== =================
# ``c_restrict`` ``<PREFIX>_RESTRICT`` ``restrict``
# ``cxx_constexpr`` ``<PREFIX>_CONSTEXPR`` ``constexpr``
# ``cxx_deleted_functions`` ``<PREFIX>_DELETED_FUNCTION`` ``= delete``
# ``cxx_extern_templates`` ``<PREFIX>_EXTERN_TEMPLATE`` ``extern``
# ``cxx_final`` ``<PREFIX>_FINAL`` ``final``
# ``cxx_noexcept`` ``<PREFIX>_NOEXCEPT`` ``noexcept``
# ``cxx_noexcept`` ``<PREFIX>_NOEXCEPT_EXPR(X)`` ``noexcept(X)``
# ``cxx_override`` ``<PREFIX>_OVERRIDE`` ``override``
# ========================== =================================== =================
#
# Compatibility Implementation Macros
# ===================================
#
# Some features are suitable for wrapping in a macro with a backward
# compatibility implementation if the compiler does not support the feature.
#
# When the ``cxx_static_assert`` feature is not provided by the compiler,
# a compatibility implementation is available via the
# ``<PREFIX>_STATIC_ASSERT(COND)`` and
# ``<PREFIX>_STATIC_ASSERT_MSG(COND, MSG)`` function-like macros. The macros
# expand to ``static_assert`` where that compiler feature is available, and
# to a compatibility implementation otherwise. In the first form, the
# condition is stringified in the message field of ``static_assert``. In
# the second form, the message ``MSG`` is passed to the message field of
# ``static_assert``, or ignored if using the backward compatibility
# implementation.
#
# ====================== ================================ ===================
# Feature Define Symbol
# ====================== ================================ ===================
# ``cxx_alignas`` ``<PREFIX>_ALIGNAS`` ``alignas``
# ``cxx_alignof`` ``<PREFIX>_ALIGNOF`` ``alignof``
# ``cxx_nullptr`` ``<PREFIX>_NULLPTR`` ``nullptr``
# ``cxx_static_assert`` ``<PREFIX>_STATIC_ASSERT`` ``static_assert``
# ``cxx_static_assert`` ``<PREFIX>_STATIC_ASSERT_MSG`` ``static_assert``
# ====================== ================================ ===================
#=============================================================================
# Copyright 2014 Stephen Kelly <steveire@gmail.com>
#
# 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.)
include(${CMAKE_CURRENT_LIST_DIR}/CMakeParseArguments.cmake)
include(${CMAKE_CURRENT_LIST_DIR}/CMakeCompilerIdDetection.cmake)
function(_load_compiler_variables CompilerId lang)
include("${CMAKE_ROOT}/Modules/Compiler/${CompilerId}-${lang}-FeatureTests.cmake" OPTIONAL)
set(_cmake_oldestSupported_${CompilerId} ${_cmake_oldestSupported} PARENT_SCOPE)
foreach(feature ${ARGN})
set(_cmake_feature_test_${CompilerId}_${feature} ${_cmake_feature_test_${feature}} PARENT_SCOPE)
endforeach()
endfunction()
function(write_compiler_detection_header
file_keyword file_arg
prefix_keyword prefix_arg
)
if (NOT file_keyword STREQUAL FILE)
message(FATAL_ERROR "write_compiler_detection_header: FILE parameter missing.")
endif()
if (NOT prefix_keyword STREQUAL PREFIX)
message(FATAL_ERROR "write_compiler_detection_header: PREFIX parameter missing.")
endif()
set(options)
set(oneValueArgs VERSION EPILOG PROLOG)
set(multiValueArgs COMPILERS FEATURES)
cmake_parse_arguments(_WCD "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
if (NOT _WCD_COMPILERS)
message(FATAL_ERROR "Invalid arguments. write_compiler_detection_header requires at least one compiler.")
endif()
if (NOT _WCD_FEATURES)
message(FATAL_ERROR "Invalid arguments. write_compiler_detection_header requires at least one feature.")
endif()
if(_WCD_UNPARSED_ARGUMENTS)
message(FATAL_ERROR "Unparsed arguments: ${_WCD_UNPARSED_ARGUMENTS}")
endif()
if(NOT _WCD_VERSION)
set(_WCD_VERSION ${CMAKE_MINIMUM_REQUIRED_VERSION})
endif()
if (_WCD_VERSION VERSION_LESS 3.1.0) # Version which introduced this function
message(FATAL_ERROR "VERSION parameter too low.")
endif()
set(compilers
GNU
)
foreach(_comp ${_WCD_COMPILERS})
list(FIND compilers ${_comp} idx)
if (idx EQUAL -1)
message(FATAL_ERROR "Unsupported compiler ${_comp}.")
endif()
endforeach()
set(file_content "
// This is a generated file. Do not edit!
#ifndef ${prefix_arg}_COMPILER_DETECTION_H
#define ${prefix_arg}_COMPILER_DETECTION_H
")
if (_WCD_PROLOG)
set(file_content "${file_content}\n${_WCD_PROLOG}\n")
endif()
foreach(feature ${_WCD_FEATURES})
if (feature MATCHES "^cxx_")
list(APPEND _langs CXX)
list(APPEND CXX_features ${feature})
elseif (feature MATCHES "^c_")
list(APPEND _langs C)
list(APPEND C_features ${feature})
else()
message(FATAL_ERROR "Unsupported feature ${feature}.")
endif()
endforeach()
list(REMOVE_DUPLICATES _langs)
foreach(_lang ${_langs})
get_property(known_features GLOBAL PROPERTY CMAKE_${_lang}_KNOWN_FEATURES)
foreach(feature ${${_lang}_features})
list(FIND known_features ${feature} idx)
if (idx EQUAL -1)
message(FATAL_ERROR "Unsupported feature ${feature}.")
endif()
endforeach()
if(_lang STREQUAL CXX)
set(file_content "${file_content}\n#ifdef __cplusplus\n")
else()
set(file_content "${file_content}\n#ifndef __cplusplus\n")
endif()
compiler_id_detection(ID_CONTENT ${_lang} PREFIX ${prefix_arg}_
ID_DEFINE
)
set(file_content "${file_content}${ID_CONTENT}\n")
set(pp_if "if")
foreach(compiler ${_WCD_COMPILERS})
_load_compiler_variables(${compiler} ${_lang} ${${_lang}_features})
set(file_content "${file_content}\n# ${pp_if} ${prefix_arg}_COMPILER_IS_${compiler}\n")
set(file_content "${file_content}
# if !(${_cmake_oldestSupported_${compiler}})
# error Unsupported compiler version
# endif\n")
set(pp_if "elif")
foreach(feature ${${_lang}_features})
string(TOUPPER ${feature} feature_upper)
set(feature_PP "COMPILER_${feature_upper}")
set(_define_item "\n# define ${prefix_arg}_${feature_PP} 0\n")
if (_cmake_feature_test_${compiler}_${feature} STREQUAL "1")
set(_define_item "\n# define ${prefix_arg}_${feature_PP} 1\n")
elseif (_cmake_feature_test_${compiler}_${feature})
set(_define_item "\n# define ${prefix_arg}_${feature_PP} 0\n")
set(_define_item "\n# if ${_cmake_feature_test_${compiler}_${feature}}\n# define ${prefix_arg}_${feature_PP} 1\n# else${_define_item}# endif\n")
endif()
set(file_content "${file_content}${_define_item}")
endforeach()
endforeach()
if(pp_if STREQUAL "elif")
set(file_content "${file_content}
# else
# error Unsupported compiler
# endif\n")
endif()
foreach(feature ${${_lang}_features})
string(TOUPPER ${feature} feature_upper)
set(feature_PP "COMPILER_${feature_upper}")
set(def_name ${prefix_arg}_${feature_PP})
if (feature STREQUAL c_restrict)
set(def_value "${prefix_arg}_RESTRICT")
set(file_content "${file_content}
# if ${def_name}
# define ${def_value} restrict
# else
# define ${def_value}
# endif
\n")
endif()
if (feature STREQUAL cxx_constexpr)
set(def_value "${prefix_arg}_DECL_${feature_upper}")
set(file_content "${file_content}
# if ${def_name}
# define ${def_value} constexpr
# else
# define ${def_value}
# endif
\n")
endif()
if (feature STREQUAL cxx_final)
set(def_value "${prefix_arg}_DECL_${feature_upper}")
set(file_content "${file_content}
# if ${def_name}
# define ${def_value} final
# else
# define ${def_value}
# endif
\n")
endif()
if (feature STREQUAL cxx_override)
set(def_value "${prefix_arg}_DECL_${feature_upper}")
set(file_content "${file_content}
# if ${def_name}
# define ${def_value} override
# else
# define ${def_value}
# endif
\n")
endif()
if (feature STREQUAL cxx_static_assert)
set(def_value "${prefix_arg}_STATIC_ASSERT(X)")
set(def_value_msg "${prefix_arg}_STATIC_ASSERT_MSG(X, MSG)")
set(static_assert_struct "template<bool> struct ${prefix_arg}StaticAssert;\ntemplate<> struct ${prefix_arg}StaticAssert<true>{};\n")
set(def_standard "# define ${def_value} static_assert(X, #X)\n# define ${def_value_msg} static_assert(X, MSG)")
set(def_alternative "${static_assert_struct}# define ${def_value} sizeof(${prefix_arg}StaticAssert<X>)\n# define ${def_value_msg} sizeof(${prefix_arg}StaticAssert<X>)")
set(file_content "${file_content}# if ${def_name}\n${def_standard}\n# else\n${def_alternative}\n# endif\n\n")
endif()
if (feature STREQUAL cxx_alignas)
set(def_value "${prefix_arg}_ALIGNAS(X)")
set(file_content "${file_content}
# if ${def_name}
# define ${def_value} alignas(X)
# elif ${prefix_arg}_COMPILER_IS_GNU
# define ${def_value} __attribute__ ((__aligned__(X)))
# else
# define ${def_value}
# endif
\n")
endif()
if (feature STREQUAL cxx_alignof)
set(def_value "${prefix_arg}_ALIGNOF(X)")
set(file_content "${file_content}
# if ${def_name}
# define ${def_value} alignof(X)
# elif ${prefix_arg}_COMPILER_IS_GNU
# define ${def_value} __alignof__(X)
# endif
\n")
endif()
if (feature STREQUAL cxx_deleted_functions)
set(def_value "${prefix_arg}_DELETED_FUNCTION")
set(file_content "${file_content}
# if ${def_name}
# define ${def_value} = delete
# else
# define ${def_value}
# endif
\n")
endif()
if (feature STREQUAL cxx_extern_templates)
set(def_value "${prefix_arg}_EXTERN_TEMPLATE")
set(file_content "${file_content}
# if ${def_name}
# define ${def_value} extern
# else
# define ${def_value}
# endif
\n")
endif()
if (feature STREQUAL cxx_noexcept)
set(def_value "${prefix_arg}_NOEXCEPT")
set(file_content "${file_content}
# if ${def_name}
# define ${def_value} noexcept
# define ${def_value}_EXPR(X) noexcept(X)
# else
# define ${def_value}
# define ${def_value}_EXPR(X)
# endif
\n")
endif()
if (feature STREQUAL cxx_nullptr)
set(def_value "${prefix_arg}_NULLPTR")
set(file_content "${file_content}
# if ${def_name}
# define ${def_value} nullptr
# else
# define ${def_value} static_cast<void*>(0)
# endif
\n")
endif()
endforeach()
set(file_content "${file_content}#endif\n")
endforeach()
if (_WCD_EPILOG)
set(file_content "${file_content}\n${_WCD_EPILOG}\n")
endif()
set(file_content "${file_content}\n#endif")
set(CMAKE_CONFIGURABLE_FILE_CONTENT ${file_content})
configure_file("${CMAKE_ROOT}/Modules/CMakeConfigurableFile.in"
"${file_arg}"
@ONLY
)
endfunction()
|
