libqtxdg-packaging/cmake/compiler_settings.cmake

#=============================================================================
# Copyright 2015 Luís Pereira <luis.artur.pereira@gmail.com>
# Copyright 2013 Hong Jen Yee (PCMan) <pcman.tw@gmail.com>
#
# 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 SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#=============================================================================

#-----------------------------------------------------------------------------
# Honor visibility properties for all target types.
#
# The ``<LANG>_VISIBILITY_PRESET`` and
# ``VISIBILITY_INLINES_HIDDEN`` target properties affect visibility
# of symbols during dynamic linking.  When first introduced these properties
# affected compilation of sources only in shared libraries, module libraries,
# and executables with the ``ENABLE_EXPORTS`` property set.  This
# was sufficient for the basic use cases of shared libraries and executables
# with plugins.  However, some sources may be compiled as part of static
# libraries or object libraries and then linked into a shared library later.
# CMake 3.3 and above prefer to honor these properties for sources compiled
# in all target types.  This policy preserves compatibility for projects
# expecting the properties to work only for some target types.
#
# The ``OLD`` behavior for this policy is to ignore the visibility properties
# for static libraries, object libraries, and executables without exports.
# The ``NEW`` behavior for this policy is to honor the visibility properties
# for all target types.
#
# This policy was introduced in CMake version 3.3.  CMake version
# 3.3.0 warns when the policy is not set and uses ``OLD`` behavior. Use
# the ``cmake_policy()`` command to set it to ``OLD`` or ``NEW``
# explicitly.
#-----------------------------------------------------------------------------
if(COMMAND CMAKE_POLICY)
    if (POLICY CMP0063)
        cmake_policy(SET CMP0063 NEW)
    endif()
endif()


#-----------------------------------------------------------------------------
# Detect Clang compiler
#-----------------------------------------------------------------------------
if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
    set(QTXDG_COMPILER_IS_CLANGCXX 1)
endif()


#-----------------------------------------------------------------------------
# Global definitions
#-----------------------------------------------------------------------------
if (CMAKE_BUILD_TYPE MATCHES "Debug")
  add_definitions(-DQT_STRICT_ITERATORS)
endif()


#-----------------------------------------------------------------------------
# Set visibility to hidden to hide symbols, unless they're exported manually
# in the code
#-----------------------------------------------------------------------------
set(CMAKE_CXX_VISIBILITY_PRESET hidden)
set(CMAKE_VISIBILITY_INLINES_HIDDEN 1)


#-----------------------------------------------------------------------------
# Disable exceptions
#-----------------------------------------------------------------------------
if (CMAKE_COMPILER_IS_GNUCXX OR QTXDG_COMPILER_IS_CLANGCXX)
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-exceptions")
endif()

#-----------------------------------------------------------------------------
# Common warning flags
#-----------------------------------------------------------------------------
set(QTXDG_COMMON_WARNING_FLAGS "-Wall -Wextra -Wchar-subscripts -Wno-long-long -Wpointer-arith -Wundef -Wformat-security")


#-----------------------------------------------------------------------------
# Warning flags
#-----------------------------------------------------------------------------
if (CMAKE_COMPILER_IS_GNUCXX OR QTXDG_COMPILER_IS_CLANGCXX)
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${__QTXDG_COMMON_WARNING_FLAGS} -Wnon-virtual-dtor -Woverloaded-virtual -Wpedantic")
endif()

if (QTXDG_COMPILER_IS_CLANGCXX)
    # qCDebug(), qCWarning, etc trigger a very verbose warning, about.... nothing. Disable it.
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-gnu-zero-variadic-macro-arguments")
endif()

list(APPEND QTXDG_WARNING_FLAGS ${QTXDG_COMMON_WARNING_FLAGS})

#-----------------------------------------------------------------------------
# String conversion flags
#-----------------------------------------------------------------------------
add_definitions(
    -DQT_USE_QSTRINGBUILDER
    -DQT_NO_CAST_FROM_ASCII
    -DQT_NO_CAST_TO_ASCII
    -DQT_NO_URL_CAST_FROM_STRING
    -DQT_NO_CAST_FROM_BYTEARRAY
)

#-----------------------------------------------------------------------------
# Linker flags
# Do not allow undefined symbols
#-----------------------------------------------------------------------------
if (CMAKE_COMPILER_IS_GNUCXX OR QTXDG_COMPILER_IS_CLANGCXX)
    # -Bsymbolic-functions: replace dynamic symbols used internally in
    #                       shared libs with direct addresses.
    set(SYMBOLIC_FLAGS
        "-Wl,-Bsymbolic-functions -Wl,-Bsymbolic"
    )
    set(CMAKE_SHARED_LINKER_FLAGS
        "-Wl,--no-undefined ${SYMBOLIC_FLAGS} ${CMAKE_SHARED_LINKER_FLAGS}"
    )
    set(CMAKE_MODULE_LINKER_FLAGS
        "-Wl,--no-undefined ${SYMBOLIC_FLAGS} ${CMAKE_MODULE_LINKER_FLAGS}"
    )
    set(CMAKE_EXE_LINKER_FLAGS
        "${SYMBOLIC_FLAGS} ${CMAKE_EXE_LINKER_FLAGS}"
    )

endif()

#-----------------------------------------------------------------------------
# Turn on more aggrassive optimizations not supported by CMake
# References: https://wiki.qt.io/Performance_Tip_Startup_Time
#-----------------------------------------------------------------------------
if (CMAKE_COMPILER_IS_GNUCXX OR QTXDG_COMPILER_IS_CLANGCXX)
    # -flto: use link-time optimizations to generate more efficient code
    if (CMAKE_COMPILER_IS_GNUCXX)
        set(LTO_FLAGS "-flto -fuse-linker-plugin")
        # When building static libraries with LTO in gcc >= 4.9,
        # "gcc-ar" and "gcc-ranlib" should be used instead of "ar" and "ranlib".
        # references:
        #   https://gcc.gnu.org/gcc-4.9/changes.html
        #   http://hubicka.blogspot.tw/2014/04/linktime-optimization-in-gcc-2-firefox.html
        #   https://github.com/monero-project/monero/pull/1065/commits/1855213c8fb8f8727f4107716aab8e7ba826462b
        if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "4.9.0")  # gcc >= 4.9
            set(CMAKE_AR "gcc-ar")
            set(CMAKE_RANLIB "gcc-ranlib")
        endif()
    elseif (QTXDG_COMPILER_IS_CLANGCXX)
        # The link-time optimization of clang++/llvm seems to be too aggrassive.
        # After testing, it breaks the signal/slots of QObject sometimes.
        # So disable it for now until there is a solution.
        # set(LTO_FLAGS "-flto")
    endif()
    # apply these options to "Release" build type only
    set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} ${LTO_FLAGS}")
endif()