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mirror of https://github.com/Kitware/CMake.git synced 2025-05-08 22:37:04 +08:00

Merge topic 'patch-FindProtobuf'

1bdb0ee1b8 FindProtobuf: Deprecate protobuf_generate_*() and update documentation

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !10742
This commit is contained in:
Brad King 2025-05-06 13:43:15 +00:00 committed by Kitware Robot
commit 015cada32d
4 changed files with 497 additions and 178 deletions

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@ -140,7 +140,7 @@ Modules
(such as for related tools or data and plugin install paths).
* The :module:`FindProtobuf` module gained a new
:command:`protobuf_generate_python` function to generate python
:command:`protobuf_generate_python` command to generate Python
sources from ``.proto`` files.
* The :module:`FindTIFF` module learned to search separately for

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@ -3,3 +3,7 @@ FindProtobuf
* The :module:`FindProtobuf` module's :command:`protobuf_generate(DEPENDENCIES)`
command argument now accepts multiple values.
* The :module:`FindProtobuf` module's commands :command:`protobuf_generate_cpp`
and :command:`protobuf_generate_python` together with their hint variables
``Protobuf_IMPORT_DIRS`` and ``PROTOBUF_GENERATE_CPP_APPEND_PATH`` are now
deprecated in favor of :command:`protobuf_generate`.

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@ -5,204 +5,211 @@
FindProtobuf
------------
Locate and configure the Google Protocol Buffers library.
.. note::
If the Protobuf library is built and installed using its CMake-based
build system, it provides a :ref:`package configuration file
<Config File Packages>` for use with the :command:`find_package` command
in *config mode*:
.. code-block:: cmake
find_package(Protobuf CONFIG)
In this case, imported targets and CMake commands such as
:command:`protobuf_generate` are provided by the upstream package rather
than this module. Additionally, some variables documented here are not
available in *config mode*, as imported targets are preferred. For usage
details, refer to the upstream documentation, which is the recommended
way to use Protobuf with CMake.
This module works only in *module mode*.
This module finds the Protocol Buffers library (Protobuf) in *module mode*:
.. code-block:: cmake
find_package(Protobuf [<version>] [...])
Protobuf is an open-source, language-neutral, and platform-neutral mechanism
for serializing structured data, developed by Google. It is commonly used
for data exchange between programs or across networks.
.. versionadded:: 3.6
Support for :command:`find_package` version checks.
Support for the ``<version>`` argument in
:command:`find_package(Protobuf \<version\>)`.
.. versionchanged:: 3.6
All input and output variables use the ``Protobuf_`` prefix.
Variables with ``PROTOBUF_`` prefix are still supported for compatibility.
All input and output variables use the ``Protobuf_`` prefix. Variables
with ``PROTOBUF_`` prefix are supported for backward compatibility.
The following variables can be set and are optional:
Imported Targets
^^^^^^^^^^^^^^^^
``Protobuf_SRC_ROOT_FOLDER``
When compiling with MSVC, if this cache variable is set
the protobuf-default VS project build locations
(vsprojects/Debug and vsprojects/Release
or vsprojects/x64/Debug and vsprojects/x64/Release)
will be searched for libraries and binaries.
``Protobuf_IMPORT_DIRS``
List of additional directories to be searched for
imported .proto files.
``Protobuf_DEBUG``
.. versionadded:: 3.6
This module provides the following :ref:`Imported Targets`:
Show debug messages.
``Protobuf_USE_STATIC_LIBS``
``protobuf::libprotobuf``
.. versionadded:: 3.9
Set to ON to force the use of the static libraries.
Default is OFF.
Target encapsulating the Protobuf library usage requirements, available if
Protobuf library is found.
Defines the following variables:
``protobuf::libprotobuf-lite``
.. versionadded:: 3.9
Target encapsulating the ``protobuf-lite`` library usage requirements,
available if Protobuf and its lite library are found.
``protobuf::libprotoc``
.. versionadded:: 3.9
Target encapsulating the ``protoc`` library usage requirements, available
if Protobuf and its ``protoc`` library are found.
``protobuf::protoc``
.. versionadded:: 3.10
Imported executable target encapsulating the ``protoc`` compiler usage
requirements, available if Protobuf and ``protoc`` are found.
Result Variables
^^^^^^^^^^^^^^^^
This module defines the following variables:
``Protobuf_FOUND``
Found the Google Protocol Buffers library
(libprotobuf & header files)
Boolean indicating whether (the requested version of) Protobuf library is
found.
``Protobuf_VERSION``
.. versionadded:: 3.6
Version of package found.
The version of Protobuf found.
``Protobuf_INCLUDE_DIRS``
Include directories for Google Protocol Buffers
Include directories needed to use Protobuf.
``Protobuf_LIBRARIES``
The protobuf libraries
Libraries needed to link against to use Protobuf.
``Protobuf_PROTOC_LIBRARIES``
The protoc libraries
Libraries needed to link against to use the ``protoc`` library.
``Protobuf_LITE_LIBRARIES``
The protobuf-lite libraries
Libraries needed to link against to use the ``protobuf-lite`` library.
.. versionadded:: 3.9
The following :prop_tgt:`IMPORTED` targets are also defined:
Cache Variables
^^^^^^^^^^^^^^^
``protobuf::libprotobuf``
The protobuf library.
``protobuf::libprotobuf-lite``
The protobuf lite library.
``protobuf::libprotoc``
The protoc library.
``protobuf::protoc``
.. versionadded:: 3.10
The protoc compiler.
The following cache variables may also be set:
The following cache variables are also available to set or use:
``Protobuf_LIBRARY``
The protobuf library
``Protobuf_PROTOC_LIBRARY``
The protoc library
``Protobuf_INCLUDE_DIR``
The include directory for protocol buffers
The include directory containing Protobuf headers.
``Protobuf_LIBRARY``
The path to the ``protobuf`` library.
``Protobuf_PROTOC_LIBRARY``
The path to the ``protoc`` library.
``Protobuf_PROTOC_EXECUTABLE``
The protoc compiler
The path to the ``protoc`` compiler.
``Protobuf_LIBRARY_DEBUG``
The protobuf library (debug)
The path to the ``protobuf`` debug library.
``Protobuf_PROTOC_LIBRARY_DEBUG``
The protoc library (debug)
The path to the ``protoc`` debug library.
``Protobuf_LITE_LIBRARY``
The protobuf lite library
The path to the ``protobuf-lite`` library.
``Protobuf_LITE_LIBRARY_DEBUG``
The protobuf lite library (debug)
The path to the ``protobuf-lite`` debug library.
``Protobuf_SRC_ROOT_FOLDER``
When compiling with MSVC, if this cache variable is set, the
protobuf-default Visual Studio project build locations will be searched for
libraries and binaries:
Example:
* ``<Protobuf_SRC_ROOT_FOLDER>/vsprojects/{Debug,Release}``, or
* ``<Protobuf_SRC_ROOT_FOLDER>/vsprojects/x64/{Debug,Release}``
.. code-block:: cmake
Hints
^^^^^
find_package(Protobuf REQUIRED)
include_directories(${Protobuf_INCLUDE_DIRS})
include_directories(${CMAKE_CURRENT_BINARY_DIR})
protobuf_generate_cpp(PROTO_SRCS PROTO_HDRS foo.proto)
protobuf_generate_cpp(PROTO_SRCS PROTO_HDRS EXPORT_MACRO DLL_EXPORT foo.proto)
protobuf_generate_cpp(PROTO_SRCS PROTO_HDRS DESCRIPTORS PROTO_DESCS foo.proto)
protobuf_generate_python(PROTO_PY foo.proto)
add_executable(bar bar.cc ${PROTO_SRCS} ${PROTO_HDRS})
target_link_libraries(bar ${Protobuf_LIBRARIES})
This module accepts the following optional variables before calling the
``find_package(Protobuf)``:
.. note::
The ``protobuf_generate_cpp`` and ``protobuf_generate_python``
functions and :command:`add_executable` or :command:`add_library`
calls only work properly within the same directory.
``Protobuf_DEBUG``
.. versionadded:: 3.6
.. command:: protobuf_generate_cpp
Boolean variable that enables debug messages of this module to be printed
for debugging purposes.
Add custom commands to process ``.proto`` files to C++:
``Protobuf_USE_STATIC_LIBS``
.. versionadded:: 3.9
.. code-block:: cmake
Set to ON to force the use of the static libraries. Default is OFF.
protobuf_generate_cpp (
<srcs-var> <hdrs-var>
[DESCRIPTORS <var>]
[EXPORT_MACRO <macro>]
[<proto-file>...])
Commands
^^^^^^^^
``<srcs-var>``
Variable to define with autogenerated source files
This module provides the following commands if Protobuf is found:
``<hdrs-var>``
Variable to define with autogenerated header files
``DESCRIPTORS <var>``
.. versionadded:: 3.10
Variable to define with autogenerated descriptor files, if requested.
``EXPORT_MACRO <macro>``
is a macro which should expand to ``__declspec(dllexport)`` or
``__declspec(dllimport)`` depending on what is being compiled.
``<proto-file>...``
``.proto`` files
.. command:: protobuf_generate_python
.. versionadded:: 3.4
Add custom commands to process ``.proto`` files to Python:
.. code-block:: cmake
protobuf_generate_python (<py-srcs-var> [<proto-file>...])
``<py-srcs-var>``
Variable to define with autogenerated Python files
``<proto-file>...``
``.proto`` files
Generating Source Files
"""""""""""""""""""""""
.. command:: protobuf_generate
.. versionadded:: 3.13
Automatically generate source files from ``.proto`` schema files at build time:
Automatically generates source files from ``.proto`` schema files at build
time:
.. code-block:: cmake
protobuf_generate(
TARGET <target>
[TARGET <target>]
[LANGUAGE <lang>]
[OUT_VAR <var>]
[OUT_VAR <variable>]
[EXPORT_MACRO <macro>]
[PROTOC_OUT_DIR <dir>]
[PROTOC_OUT_DIR <out-dir>]
[PLUGIN <plugin>]
[PLUGIN_OPTIONS <plugin-options>]
[DEPENDENCIES <dependencies>...]
[PROTOS <proto-file>...]
[IMPORT_DIRS <dir>...]
[GENERATE_EXTENSIONS <extension>...]
[PROTOC_OPTIONS <option>...]
[PROTOS <proto-files>...]
[IMPORT_DIRS <dirs>...]
[APPEND_PATH]
[GENERATE_EXTENSIONS <extensions>...]
[PROTOC_OPTIONS <options>...]
[PROTOC_EXE <executable>]
[APPEND_PATH])
[DESCRIPTORS]
)
``APPEND_PATH``
A flag that causes the base path of all proto schema files to be added to
``IMPORT_DIRS``.
``TARGET <target>``
The CMake target to which the generated files are added as sources. This
option is required when ``OUT_VAR <variable>`` is not used.
``LANGUAGE <lang>``
A single value: cpp or python. Determines what kind of source files are
being generated. Defaults to cpp.
A single value: ``cpp`` or ``python``. Determines the kind of source
files to generate. Defaults to ``cpp``. For other languages, use the
``GENERATE_EXTENSIONS`` option.
``OUT_VAR <var>``
Name of a CMake variable that will be filled with the paths to the generated
source files.
``OUT_VAR <variable>``
The name of a CMake variable that will be populated with the paths to
the generated source files.
``EXPORT_MACRO <macro>``
Name of a macro that is applied to all generated Protobuf message classes
and extern variables. It can, for example, be used to declare DLL exports.
The name of a preprocessor macro applied to all generated Protobuf message
classes and extern variables. This can be used, for example, to declare
DLL exports. The macro should expand to ``__declspec(dllexport)`` or
``__declspec(dllimport)``, depending on what is being compiled.
``PROTOC_OUT_DIR <dir>``
Output directory of generated source files. Defaults to ``CMAKE_CURRENT_BINARY_DIR``.
This option is only used when ``LANGUAGE`` is ``cpp``.
``PROTOC_OUT_DIR <out-dir>``
The output directory for generated source files. Defaults to:
:variable:`CMAKE_CURRENT_BINARY_DIR`.
``PLUGIN <plugin>``
.. versionadded:: 3.21
An optional plugin executable. This could, for example, be the path to
An optional plugin executable. This could be, for example, the path to
``grpc_cpp_plugin``.
``PLUGIN_OPTIONS <plugin-options>``
.. versionadded:: 3.28
Additional options provided to the plugin, such as ``generate_mock_code=true``
for the gRPC cpp plugin.
Additional options passed to the plugin, such as ``generate_mock_code=true``
for the gRPC C++ plugin.
``DEPENDENCIES <dependencies>...``
.. versionadded:: 3.28
@ -213,50 +220,358 @@ Example:
.. versionchanged:: 4.1
This argument now accepts multiple values (``DEPENDENCIES a b c...``).
Previously only a single value could be specified
Previously, only a single value could be specified
(``DEPENDENCIES "a;b;c;..."``).
``TARGET <target>``
CMake target that will have the generated files added as sources.
``PROTOS <proto-files>...``
A list of ``.proto`` schema files to process. If ``<target>`` is also
specified, these will be combined with all ``.proto`` source files from
that target.
``PROTOS <proto-file>...``
List of proto schema files. If omitted, then every source file ending in *proto* of ``TARGET`` will be used.
``IMPORT_DIRS <dirs>...``
A list of one or more common parent directories for the schema files.
For example, if the schema file is ``proto/helloworld/helloworld.proto``
and the import directory is ``proto/``, then the generated files will be
``<out-dir>/helloworld/helloworld.pb.h`` and
``<out-dir>/helloworld/helloworld.pb.cc``.
``IMPORT_DIRS <dir>...``
A common parent directory for the schema files. For example, if the schema file is
``proto/helloworld/helloworld.proto`` and the import directory ``proto/`` then the
generated files are ``${PROTOC_OUT_DIR}/helloworld/helloworld.pb.h`` and
``${PROTOC_OUT_DIR}/helloworld/helloworld.pb.cc``.
``APPEND_PATH``
If specified, the base paths of all proto schema files are appended to
``IMPORT_DIRS`` (it causes ``protoc`` to be invoked with ``-I`` argument
for each directory containing a ``.proto`` file).
``GENERATE_EXTENSIONS <extension>...``
If LANGUAGE is omitted then this must be set to the extensions that protoc generates.
``GENERATE_EXTENSIONS <extensions>...``
If ``LANGUAGE`` is omitted, this must be set to specify the extensions
generated by ``protoc``.
``PROTOC_OPTIONS <option>...``
``PROTOC_OPTIONS <options>...``
.. versionadded:: 3.28
Additional arguments that are forwarded to protoc.
A list of additional command-line options passed directly to the
``protoc`` compiler.
``PROTOC_EXE <executable>``
.. versionadded:: 4.0
Command name, path, or CMake executable used to generate protobuf bindings.
If omitted, ``protobuf::protoc`` is used.
The command-line program, path, or CMake executable used to generate
Protobuf bindings. If omitted, ``protobuf::protoc`` imported target is
used by default.
Example:
``DESCRIPTORS``
If specified, a command-line option ``--descriptor_set_out=<proto-file>``
is appended to ``protoc`` compiler for each ``.proto`` source file,
enabling the creation of self-describing messages. This option can only
be used when ``<lang>`` is ``cpp`` and Protobuf is found in *module mode*.
.. note::
This option is not available when Protobuf is found in *config mode*.
Deprecated Commands
"""""""""""""""""""
The following commands are provided for backward compatibility.
.. note::
The ``protobuf_generate_cpp()`` and ``protobuf_generate_python()``
commands work correctly only within the same directory scope, where
``find_package(Protobuf ...)`` is called.
.. note::
If Protobuf is found in *config mode*, the ``protobuf_generate_cpp()`` and
``protobuf_generate_python()`` commands are **not available** as of
Protobuf version 3.0.0, unless the upstream package configuration hint
variable ``protobuf_MODULE_COMPATIBLE`` is set to boolean true before
calling ``find_package(Protobuf ...)``.
.. command:: protobuf_generate_cpp
.. deprecated:: 4.1
Use :command:`protobuf_generate`.
Automatically generates C++ source files from ``.proto`` schema files at
build time:
.. code-block:: cmake
protobuf_generate_cpp(
<sources-variable>
<headers-variable>
[DESCRIPTORS <variable>]
[EXPORT_MACRO <macro>]
<proto-files>...
)
``<sources-variable>``
Name of the variable to define, which will contain a list of generated
C++ source files.
``<headers-variable>``
Name of the variable to define, which will contain a list of generated
header files.
``DESCRIPTORS <variable>``
.. versionadded:: 3.10
Name of the variable to define, which will contain a list of generated
descriptor files if requested.
.. note::
This option is not available when Protobuf is found in *config mode*.
``EXPORT_MACRO <macro>``
Name of a macro that should expand to ``__declspec(dllexport)`` or
``__declspec(dllimport)``, depending on what is being compiled.
``<proto-files>...``
One of more ``.proto`` files to be processed.
.. command:: protobuf_generate_python
.. deprecated:: 4.1
Use :command:`protobuf_generate`.
.. versionadded:: 3.4
Automatically generates Python source files from ``.proto`` schema files at
build time:
.. code-block:: cmake
protobuf_generate_python(<python-sources-variable> <proto-files>...)
``<python-sources-variable>``
Name of the variable to define, which will contain a list of generated
Python source files.
``<proto-files>...``
One or more ``.proto`` files to be processed.
---------------------------------------------------------------------
The ``protobuf_generate_cpp()`` and ``protobuf_generate_python()`` commands
accept the following optional variables before being invoked:
``Protobuf_IMPORT_DIRS``
.. deprecated:: 4.1
A list of additional directories to search for imported ``.proto`` files.
``PROTOBUF_GENERATE_CPP_APPEND_PATH``
.. deprecated:: 4.1
Use :command:`protobuf_generate(APPEND_PATH)` command option.
A boolean variable that, if set to boolean true, causes ``protoc`` to be
invoked with ``-I`` argument for each directory containing a ``.proto``
file. By default, it is set to boolean true.
Examples
^^^^^^^^
Examples: Finding Protobuf
""""""""""""""""""""""""""
Finding Protobuf library:
.. code-block:: cmake
find_package(Protobuf)
Or, finding Protobuf and specifying a minimum required version:
.. code-block:: cmake
find_package(Protobuf 30)
Or, finding Protobuf and making it required (if not found, processing stops
with an error message):
.. code-block:: cmake
find_package(gRPC CONFIG REQUIRED)
find_package(Protobuf REQUIRED)
add_library(ProtoTest Test.proto)
target_link_libraries(ProtoTest PUBLIC gRPC::grpc++)
protobuf_generate(TARGET ProtoTest)
Example: Finding Protobuf in Config Mode
""""""""""""""""""""""""""""""""""""""""
When Protobuf library is built and installed using its CMake-based build
system, it can be found in *config mode*:
.. code-block:: cmake
find_package(Protobuf CONFIG)
However, some Protobuf installations might still not provide package
configuration file. The following example shows, how to use the
:variable:`CMAKE_FIND_PACKAGE_PREFER_CONFIG` variable to find Protobuf in
*config mode* and falling back to *module mode* if config file is not found:
.. code-block:: cmake
set(CMAKE_FIND_PACKAGE_PREFER_CONFIG TRUE)
find_package(Protobuf)
unset(CMAKE_FIND_PACKAGE_PREFER_CONFIG)
Example: Using Protobuf
"""""""""""""""""""""""
Finding Protobuf and linking its imported library target to a project target:
.. code-block:: cmake
find_package(Protobuf)
target_link_libraries(example PRIVATE protobuf::libprotobuf)
Example: Processing Proto Schema Files
""""""""""""""""""""""""""""""""""""""
The following example demonstrates how to process all ``*.proto`` schema
source files added to a target into C++ source files:
.. code-block:: cmake
:caption: ``CMakeLists.txt``
cmake_minimum_required(VERSION 3.24)
project(ProtobufExample)
add_executable(example main.cxx person.proto)
find_package(Protobuf)
if(Protobuf_FOUND)
protobuf_generate(TARGET example)
endif()
target_link_libraries(example PRIVATE protobuf::libprotobuf)
target_include_directories(example PRIVATE ${CMAKE_CURRENT_BINARY_DIR})
.. code-block:: proto
:caption: ``person.proto``
syntax = "proto3";
message Person {
string name = 1;
int32 id = 2;
}
.. code-block:: c++
:caption: ``main.cxx``
#include <iostream>
#include "person.pb.h"
int main()
{
Person person;
person.set_name("Alice");
person.set_id(123);
std::cout << "Name: " << person.name() << "\n";
std::cout << "ID: " << person.id() << "\n";
return 0;
}
Example: Using Protobuf and gRPC
""""""""""""""""""""""""""""""""
The following example shows how to use Protobuf and gRPC:
.. code-block:: cmake
:caption: ``CMakeLists.txt``
find_package(Protobuf REQUIRED)
find_package(gRPC CONFIG REQUIRED)
add_library(ProtoExample Example.proto)
target_link_libraries(ProtoExample PUBLIC gRPC::grpc++)
protobuf_generate(TARGET ProtoExample)
protobuf_generate(
TARGET ProtoTest
TARGET ProtoExample
LANGUAGE grpc
PLUGIN protoc-gen-grpc=$<TARGET_FILE:gRPC::grpc_cpp_plugin>
PLUGIN_OPTIONS generate_mock_code=true
GENERATE_EXTENSIONS .grpc.pb.h .grpc.pb.cc)
GENERATE_EXTENSIONS .grpc.pb.h .grpc.pb.cc
)
Examples: Upgrading Deprecated Commands
"""""""""""""""""""""""""""""""""""""""
The following example shows how to process ``.proto`` files to C++ code,
using a deprecated command and its modern replacement:
.. code-block:: cmake
:caption: ``CMakeLists.txt`` with deprecated command
find_package(Protobuf)
if(Protobuf_FOUND)
protobuf_generate_cpp(
proto_sources
proto_headers
EXPORT_MACRO DLL_EXPORT
DESCRIPTORS proto_descriptors
src/protocol/Proto1.proto
src/protocol/Proto2.proto
)
endif()
target_sources(
example
PRIVATE ${proto_sources} ${proto_headers} ${proto_descriptors}
)
target_link_libraries(example PRIVATE protobuf::libprotobuf)
.. code-block:: cmake
:caption: ``CMakeLists.txt`` with upgraded code
find_package(Protobuf)
if(Protobuf_FOUND)
protobuf_generate(
TARGET example
EXPORT_MACRO DLL_EXPORT
IMPORT_DIRS src/protocol
DESCRIPTORS
PROTOS
src/protocol/Proto1.proto
src/protocol/Proto2.proto
)
endif()
target_link_libraries(example PRIVATE protobuf::libprotobuf)
The following example shows how to process ``.proto`` files to Python code,
using a deprecated command and its modern replacement:
.. code-block:: cmake
:caption: ``CMakeLists.txt`` with deprecated command
find_package(Protobuf)
if(Protobuf_FOUND)
protobuf_generate_python(python_sources foo.proto)
endif()
add_custom_target(proto_files DEPENDS ${python_sources})
.. code-block:: cmake
:caption: ``CMakeLists.txt`` with upgraded code
find_package(Protobuf)
if(Protobuf_FOUND)
protobuf_generate(
LANGUAGE python
PROTOS foo.proto
OUT_VAR python_sources
)
endif()
add_custom_target(proto_files DEPENDS ${python_sources})
#]=======================================================================]
cmake_policy(PUSH)

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@ -35,8 +35,8 @@ add_test(NAME test_var_protoc COMMAND test_var_protoc)
add_test(NAME test_tgt_protoc_version COMMAND protobuf::protoc --version)
set(Protobuf_IMPORT_DIRS ${Protobuf_INCLUDE_DIRS})
PROTOBUF_GENERATE_CPP(PROTO_SRC PROTO_HEADER msgs/example.proto)
PROTOBUF_GENERATE_CPP(DESC_PROTO_SRC DESC_PROTO_HEADER DESCRIPTORS DESC_PROTO_DESC msgs/example_desc.proto)
protobuf_generate_cpp(PROTO_SRC PROTO_HEADER msgs/example.proto)
protobuf_generate_cpp(DESC_PROTO_SRC DESC_PROTO_HEADER DESCRIPTORS DESC_PROTO_DESC msgs/example_desc.proto)
add_library(msgs ${PROTO_SRC} ${PROTO_HEADER})
target_compile_features(msgs PRIVATE cxx_std_11)