source: mainline/meson/part/compiler_args/meson.build

#
# Copyright (c) 2019 Jiří Zárevúcky
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# - Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
#   documentation and/or other materials provided with the distribution.
# - 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.
#

# This file sets the architecture-independent compiler flags used throughout
# this repository.
# For architecture-specific flags, see $srcroot/meson/cross/$arch.

add_project_arguments(
        # TODO: Remove from project arguments and only use where necessary.
        # Any change in config forces everything to rebuild due to lack of granularity here.
        '-imacros', meson.build_root() / 'config.h',
        language : [ 'c' ],
)

add_project_link_arguments(
        '-Wl,--gc-sections',
        '-Wl,--warn-common',
        '-Wl,--fatal-warnings',
        '-Wl,-z,text',
        language : [ 'c', 'cpp' ],
)

# TODO: enable more warnings
# FIXME: -fno-builtin-strftime works around seemingly spurious format warning.
# We should investigate what's going on there.

extra_common_flags = [
        '-O' + OPTIMIZATION,
        '-fexec-charset=UTF-8',
        '-finput-charset=UTF-8',

        '-D_HELENOS_SOURCE',

        '-Wa,--fatal-warnings',
        '-Wl,-z,text',

        '-Wall',
        '-Wextra',
        '-Wwrite-strings',
        '-Wunknown-pragmas',

        '-Wno-unused-parameter',

        '-pipe',

        '-ffunction-sections',
        '-fdata-sections',
        '-fno-common',
        '-fdebug-prefix-map=' + meson.source_root() + '/=',
        '-fdebug-prefix-map=../../=',
]

if cc.get_id() != 'clang'
        # Clang's own headers emit macro redefinition warnings.
        extra_common_flags += '-Wsystem-headers'
endif

if UARCH != 'ia64'
        extra_common_flags += [ '-fvar-tracking-assignments' ]
endif

if CONFIG_DEBUG
        extra_common_flags += [ '-Werror' ]
endif

if CONFIG_LINE_DEBUG
        extra_common_flags += [ '-gdwarf-5', '-g3' ]
endif

extra_cflags = extra_common_flags + [
        '-Wmissing-prototypes',
        '-Werror-implicit-function-declaration',

        '-Wno-missing-braces',
        '-Wno-missing-field-initializers',
        '-Wno-unused-command-line-argument',
        '-Wno-unused-parameter',
        '-Wno-typedef-redefinition',
        '-Wno-clobbered',
        '-Wno-nonnull-compare',

        '-fno-builtin-strftime',
]

if CONFIG_UBSAN
        extra_cflags += '-fsanitize=undefined'
endif

extra_cppflags = extra_common_flags + [
        '-fno-exceptions',
        '-Wno-misleading-indentation',
        '-frtti',
]

w_flags = {
        'c': extra_cflags,
        'cpp': extra_cppflags,
}

# TODO: To remove noise in Meson output, we may want to cut down on
#       the explicitly checked flags and just enable those supported by
#       both gcc and clang unconditionally.

# Process flags. Only sets those that compiler supports.
foreach lang : [ 'c', 'cpp' ]
        extra_cflags = meson.get_compiler(lang).get_supported_arguments(w_flags.get(lang))
        add_project_arguments(extra_cflags, language : [ lang ])
        add_project_link_arguments(extra_cflags, language : [ lang ])
endforeach

# This flag is needed at several places, hence we define it here.
#
# For backwards compatibility we try to detect --no-warn-rwx-segments.
# However, the autodetection done by Meson also results in
# "cannot find entry symbol _start; defaulting to 00000000004000b0"
# thus the option is never supported alone. So when detecting we also
# specify --entry=main so that the stub source provided by Meson is build
# correctly.
ldflags_ignore_rwx_segments = []
if cc.has_link_argument('-Wl,--no-warn-rwx-segments,--entry=main')
    ldflags_ignore_rwx_segments += ['-Wl,--no-warn-rwx-segments']
endif