lyx_mirror/development/cmake/modules/FindCXX11Compiler.cmake
Kornel Benko 2ec243d47b Cmake build: Fine tuning
1.) If building with external iconv, remove remnants of libiconv data
  created if previousy used internal iconv
2.) Remove the variable HELP from cache to enable subsequent builds.
  (Different variable-handling on new cmake (version >= 3.18))
3.) New macro to extract cmake-known-cxx-sts features
4.) Check for CXX11-features only for a subset of possibilities
  known by the used cmake
2020-10-28 23:12:03 +01:00

163 lines
4.7 KiB
CMake

# This file is part of lyx.
#
# The module comes from the enblend project, slightly modified.
#
# Check if compiler supports C++11 features
# and which compiler switches are necessary
# CXX11_FLAG : contains the necessary compiler flag
#
# Copyright (c) 2013 Thomas Modes <tmodes@@users.sourceforge.net>
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# 3. The name of the author may not be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# This file is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with lyx; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
INCLUDE(CheckCXXSourceCompiles)
INCLUDE(FindPackageHandleStandardArgs)
# get cmake-known std numbers
# Detection of c++20 works well, but our code is not ready for it yet.
# We currently get errors with internal boost and also from our code.
set(_max_std_num 17)
lyxgetknowncmakestd(${_max_std_num} tmpnums)
if (CMAKE_CXX_COMPILER_ID MATCHES "^([cC]lang|AppleClang)$")
foreach(_num ${tmpnums})
list(APPEND CXX11_FLAG_CANDIDATES "--std=c++${_num} -Wno-deprecated-register")
endforeach()
else()
if (CYGWIN)
foreach(_num ${tmpnums})
list(APPEND CXX11_FLAG_CANDIDATES "--std=gnu++${_num}")
endforeach()
else()
if (MSVC)
# MSVC does not have a general C++11 flag, one can only switch off
# MS extensions with /Za in general or by extension with /Zc.
# Use an empty flag to ensure that CXX11_STD_REGEX is correctly set.
if (MSVC_VERSION LESS 1926)
set(CXX11_FLAG_CANDIDATES "noflagneeded")
else()
foreach(_num ${tmpnums})
list(APPEND CXX11_FLAG_CANDIDATES "/std:c++${_num}")
endforeach()
list(APPEND CXX11_FLAG_CANDIDATES "noflagneeded")
endif()
else()
set(CXX11_FLAG_CANDIDATES)
foreach(_num ${tmpnums})
list(APPEND CXX11_FLAG_CANDIDATES "--std=c++${_num}")
endforeach()
endif()
endif()
endif()
# sample openmp source code to test
SET(CXX11_TEST_SOURCE
"
template <typename T>
struct check
{
static_assert(sizeof(int) <= sizeof(T), \"not big enough\");
};
typedef check<check<bool>> right_angle_brackets;
class TestDeleted
{
public:
TestDeleted() = delete;
};
int a;
decltype(a) b;
typedef check<int> check_type;
check_type c;
check_type&& cr = static_cast<check_type&&>(c);
auto d = a;
int main() {
return 0;
};
")
# The following code snipped taken from example in http://stackoverflow.com/questions/8561850/compile-stdregex-iterator-with-gcc
set(REGEX_TEST_SOURCE
"
#include <regex>
#include <iostream>
#include <string.h>
typedef std::regex_iterator<const char *> Myiter;
int main()
{
const char *pat = \"axayaz\";
Myiter::regex_type rx(\"a\");
Myiter next(pat, pat + strlen(pat), rx);
Myiter end;
return (0);
}
")
# check c compiler
set(SAFE_CMAKE_REQUIRED_QUIET ${CMAKE_REQUIRED_QUIET})
set(CMAKE_REQUIRED_QUIET ON)
SET(SAFE_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
FOREACH(FLAG ${CXX11_FLAG_CANDIDATES})
IF("${FLAG}" STREQUAL "noflagneeded")
UNSET(CMAKE_REQUIRED_FLAGS)
ELSE()
SET(CMAKE_REQUIRED_FLAGS "${FLAG}")
ENDIF()
UNSET(CXX11_FLAG_DETECTED CACHE)
CHECK_CXX_SOURCE_COMPILES("${CXX11_TEST_SOURCE}" CXX11_FLAG_DETECTED)
IF(CXX11_FLAG_DETECTED)
SET(CXX11_FLAG "${FLAG}")
message(STATUS "CXX11_FLAG_DETECTED = \"${FLAG}\"")
set(LYX_USE_CXX11 1)
check_cxx_source_compiles("${REGEX_TEST_SOURCE}" CXX_STD_REGEX_DETECTED)
if (CXX_STD_REGEX_DETECTED)
message(STATUS "Compiler supports std_regex")
set(CXX11_STD_REGEX ON)
else()
message(STATUS "Compiler does not support std_regex")
set(CXX11_STD_REGEX OFF)
endif()
break()
ENDIF()
ENDFOREACH()
SET(CMAKE_REQUIRED_FLAGS "${SAFE_CMAKE_REQUIRED_FLAGS}")
set(CMAKE_REQUIRED_QUIET ${SAFE_CMAKE_REQUIRED_QUIET})
# handle the standard arguments for find_package
FIND_PACKAGE_HANDLE_STANDARD_ARGS(CXX11Compiler DEFAULT_MSG CXX11_FLAG)
IF("${CXX11_FLAG}" STREQUAL "noflagneeded")
SET(CXX11_FLAG "")
ENDIF()
MARK_AS_ADVANCED(CXX11_FLAG CXX11_STD_REGEX)