这个特定的解决方案(?)将适用于目标和单个翻译单元(单个.cpp
-文件)。它将需要CMake 3.7
或更新的,因为我们需要使用迭代所有现有的目标BUILDSYSTEM_TARGETS
属性,已添加到3.7
。如果您无法使用3.7
或更新版本,您可以适应apply_global_cxx_flags_to_all_targets()
获取目标列表并手动指定它们。请注意,您应该将下面的宏视为概念验证。除了非常小的项目之外,他们可能需要一些调整和改进。
第一步是迭代所有现有目标并应用CMAKE_CXX_FLAGS
给他们每个人。完成后,我们清除CMAKE_CXX_FLAGS
。您将在下面找到一个可以执行此操作的宏。这个宏可能应该在顶层底部的某个地方调用CMakeLists.txt
,当所有目标都已创建,所有标志均已设置等。值得注意的是,该命令get_property(_targets DIRECTORY PROPERTY BUILDSYSTEM_TARGETS)
在目录级别工作,所以如果您使用add_subdirectory()
,你必须在顶层调用这个宏CMakeLists.txt
该子目录的。
#
# Applies CMAKE_CXX_FLAGS to all targets in the current CMake directory.
# After this operation, CMAKE_CXX_FLAGS is cleared.
#
macro(apply_global_cxx_flags_to_all_targets)
separate_arguments(_global_cxx_flags_list UNIX_COMMAND ${CMAKE_CXX_FLAGS})
get_property(_targets DIRECTORY PROPERTY BUILDSYSTEM_TARGETS)
foreach(_target ${_targets})
target_compile_options(${_target} PUBLIC ${_global_cxx_flags_list})
endforeach()
unset(CMAKE_CXX_FLAGS)
set(_flag_sync_required TRUE)
endmacro()
该宏首先创建一个列表CMAKE_CXX_FLAGS
,然后它获取所有目标的列表并应用CMAKE_CXX_FLAGS
到每个目标。最后,CMAKE_CXX_FLAGS
已清除。_flag_sync_required
用于指示我们是否需要强制重写缓存变量。
下一步取决于您是否要从目标或特定翻译单元中删除标志。如果要从目标中删除标志,可以使用类似于以下的宏:
#
# Removes the specified compile flag from the specified target.
# _target - The target to remove the compile flag from
# _flag - The compile flag to remove
#
# Pre: apply_global_cxx_flags_to_all_targets() must be invoked.
#
macro(remove_flag_from_target _target _flag)
get_target_property(_target_cxx_flags ${_target} COMPILE_OPTIONS)
if(_target_cxx_flags)
list(REMOVE_ITEM _target_cxx_flags ${_flag})
set_target_properties(${_target} PROPERTIES COMPILE_OPTIONS "${_target_cxx_flags}")
endif()
endmacro()
从特定翻译单元中删除标志有点棘手(除非我错过了一些东西)。无论如何,我们的想法是首先从文件所属的目标获取编译选项,然后将所述选项应用于该目标中的所有源文件,这允许我们操作单个文件的编译标志。为此,我们为要从中删除标志的每个文件维护一个编译标志的缓存列表,当请求删除时,我们将其从缓存列表中删除,然后重新应用剩余的标志。目标本身的编译选项被清除。
#
# Removes the specified compiler flag from the specified file.
# _target - The target that _file belongs to
# _file - The file to remove the compiler flag from
# _flag - The compiler flag to remove.
#
# Pre: apply_global_cxx_flags_to_all_targets() must be invoked.
#
macro(remove_flag_from_file _target _file _flag)
get_target_property(_target_sources ${_target} SOURCES)
# Check if a sync is required, in which case we'll force a rewrite of the cache variables.
if(_flag_sync_required)
unset(_cached_${_target}_cxx_flags CACHE)
unset(_cached_${_target}_${_file}_cxx_flags CACHE)
endif()
get_target_property(_${_target}_cxx_flags ${_target} COMPILE_OPTIONS)
# On first entry, cache the target compile flags and apply them to each source file
# in the target.
if(NOT _cached_${_target}_cxx_flags)
# Obtain and cache the target compiler options, then clear them.
get_target_property(_target_cxx_flags ${_target} COMPILE_OPTIONS)
set(_cached_${_target}_cxx_flags "${_target_cxx_flags}" CACHE INTERNAL "")
set_target_properties(${_target} PROPERTIES COMPILE_OPTIONS "")
# Apply the target compile flags to each source file.
foreach(_source_file ${_target_sources})
# Check for pre-existing flags set by set_source_files_properties().
get_source_file_property(_source_file_cxx_flags ${_source_file} COMPILE_FLAGS)
if(_source_file_cxx_flags)
separate_arguments(_source_file_cxx_flags UNIX_COMMAND ${_source_file_cxx_flags})
list(APPEND _source_file_cxx_flags "${_target_cxx_flags}")
else()
set(_source_file_cxx_flags "${_target_cxx_flags}")
endif()
# Apply the compile flags to the current source file.
string(REPLACE ";" " " _source_file_cxx_flags_string "${_source_file_cxx_flags}")
set_source_files_properties(${_source_file} PROPERTIES COMPILE_FLAGS "${_source_file_cxx_flags_string}")
endforeach()
endif()
list(FIND _target_sources ${_file} _file_found_at)
if(_file_found_at GREATER -1)
if(NOT _cached_${_target}_${_file}_cxx_flags)
# Cache the compile flags for the specified file.
# This is the list that we'll be removing flags from.
get_source_file_property(_source_file_cxx_flags ${_file} COMPILE_FLAGS)
separate_arguments(_source_file_cxx_flags UNIX_COMMAND ${_source_file_cxx_flags})
set(_cached_${_target}_${_file}_cxx_flags ${_source_file_cxx_flags} CACHE INTERNAL "")
endif()
# Remove the specified flag, then re-apply the rest.
list(REMOVE_ITEM _cached_${_target}_${_file}_cxx_flags ${_flag})
string(REPLACE ";" " " _cached_${_target}_${_file}_cxx_flags_string "${_cached_${_target}_${_file}_cxx_flags}")
set_source_files_properties(${_file} PROPERTIES COMPILE_FLAGS "${_cached_${_target}_${_file}_cxx_flags_string}")
endif()
endmacro()
Example
我们有一个非常简单的项目结构:
source/
CMakeLists.txt
foo.cpp
bar.cpp
main.cpp
我们假设foo.cpp
违反-Wunused-variable
,我们想要禁用该特定文件上的该标志。为了bar.cpp
,我们想要禁用-Werror
. For main.cpp
,我们要删除-O2
,无论出于何种原因。
CMakeLists.txt
cmake_minimum_required(VERSION 3.7 FATAL_ERROR)
project(MyProject)
# Macros omitted to save space.
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O2 -Wunused-variable")
# CMake will apply this to all targets, so this will work too.
add_compile_options("-Werror")
add_executable(MyTarget foo.cpp bar.cpp main.cpp)
apply_global_cxx_flags_to_all_targets()
remove_flag_from_file(MyTarget foo.cpp -Wunused-variable)
remove_flag_from_file(MyTarget bar.cpp -Werror)
remove_flag_from_file(MyTarget main.cpp -O2)
如果您想从目标中删除标志,您可以使用remove_flag_from_target()
, 例如:remove_flag_from_target(MyTarget -O2)
Result
应用宏之前的输出
clang++ -Werror -O2 -Wunused-variable -o foo.cpp.o -c foo.cpp
clang++ -Werror -O2 -Wunused-variable -o bar.cpp.o -c bar.cpp
clang++ -Werror -O2 -Wunused-variable -o main.cpp.o -c main.cpp
应用宏后的输出
clang++ -Werror -O2 -o foo.cpp.o -c foo.cpp
clang++ -O2 -Wunused-variable -o bar.cpp.o -c bar.cpp
clang++ -Werror -Wunused-variable -o main.cpp.o -c main.cpp
最后的笔记
如前所述,这应该被视为概念验证。有几个直接问题需要考虑:
- 它只考虑
CMAKE_CXX_FLAGS
(对于所有构建类型都是通用的),而不是CMAKE_CXX_FLAGS_<DEBUG|RELEASE>
etc.
- 宏一次只能处理一个标志
-
remove_flag_from_file()
一次只能处理一个目标和输入文件作为输入。
-
remove_flag_from_file()
expects a filename, not a path. Passing, say, source/foobar/foobar.cpp
will not work, since source/foobar/foobar.cpp
will be compared against foobar.cpp
. This can be fixed by using get_source_file_property()
and the LOCATION
property and placing a precondition that _file
is a full path.
-
remove_flag_from_file()
或许可以大大优化和改进。
- 致电给
separate_arguments()
假设是 Unix。
其中大多数应该很容易修复。
我希望这至少能推动您朝着解决这个问题的正确方向前进。如果我需要在答案中添加一些内容,请告诉我。