[CMake] How can I create a C executable and C++ library from the same source
Robert Maynard
robert.maynard at kitware.com
Wed Jan 17 14:39:23 EST 2018
As stated CMake tracks source files globally so they can only have a single
language.
Project that I work on have migrated over to using file(GENERATE) to
produce the files as it only
requires a couple lines of CMake code.
get_filename_component(c_fname "${c_source_file}" NAME_WE)
get_filename_component(c_fullpath "${c_source_file}" ABSOLUTE)
file(GENERATE
OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${c_fname}.cpp
CONTENT "#include \"${c_fullpath}\"")
What ever approach you take I recommend not using an approach that copies
the contents of the
source file itself. Those will generally than require CMake to re-run every
time you modify the file. Instead
use an include statement so CMake won't re-run.
On Wed, Jan 17, 2018 at 1:29 PM, J Decker <d3ck0r at gmail.com> wrote:
> No.
> CMake tracks each source file name exactly once. If you set properties on
> it, it will be treated that way always. Have to make a copy of the source
> to cpp...
>
> copies to cmake_binary_dir/<source name>
> plusplus_file_dup is the resulting list
> ( https://github.com/d3x0r/SACK/blob/master/CMakeLists.txt#L655 )
>
> (really this is just for headers... src/csrc.h should be
> ${binary}/src/csrc.h in target too because #include "crsc.h"
>
> FOREACH(SOURCE ${PLUSPLUS_FILES_TO_COPY})
> if( ${SOURCE} MATCHES "${SOURCES_ROOT}(.*)$" )
> set( BASENAME ${CMAKE_MATCH_1} )
> set( plusplus_file_dup ${plusplus_file_dup} ${CMAKE_BINARY_DIR}/${BASENAME}
> )
> add_custom_command( OUTPUT ${CMAKE_BINARY_DIR}/${BASENAME}
> DEPENDS ${SOURCE}
> COMMAND ${CMAKE_COMMAND} -E copy_if_different
> ${SOURCE} ${CMAKE_BINARY_DIR}/${BASENAME}
> #COMMAND ${CMAKE_COMMAND} -E touch
> ${CMAKE_BINARY_DIR}/${BASENAME}
> )
> else()
> endif()
> ENDFOREACH(SOURCE)
>
>
> ---------------------
> ( https://github.com/d3x0r/SACK/blob/master/CMakeLists.txt#L672 )
> THis make s abetter copy routine; it tests to see the type of header(file)
> and possible substitutions... still kinda some debugging coments (#) in
> there... this adds it as a rule, so it only generates the target source if
> the source is referenced. therefore also onlly when those C files change
> do new copies get made.
>
> macro( COPY_CPLUSPLUS FILE_LIST )
> FOREACH(SOURCE ${ARGN} )
> if( ${SOURCE} MATCHES "${SACK_BASE}/(.*)\\.c$" )
> set( FILEOK 1 )
> set( BASENAME ${CMAKE_MATCH_1} )
> set( FILEEXT .cpp )
> elseif( ${SOURCE} MATCHES "${SACK_BASE}/(.*)\\.h$" )
> set( FILEOK 1 )
> set( BASENAME ${CMAKE_MATCH_1} )
> set( FILEEXT .h )
> elseif( ${SOURCE} MATCHES "(.*)\\.c$" )
> set( FILEOK 1 )
> set( BASENAME ${CMAKE_MATCH_1} )
> set( FILEEXT .cpp )
> elseif( ${SOURCE} MATCHES "(.*)\\.h$" )
> set( FILEOK 1 )
> set( BASENAME ${CMAKE_MATCH_1} )
> set( FILEEXT .h )
> else()
> set( FILEOK 0 )
> set( BASENAME "" )
> endif()
>
> if( FILEOK )
> get_source_file_property(SOURCE_FOLDER ${SOURCE} FOLDER)
>
> if( ${SOURCE} MATCHES "^${PROJECT_SOURCE_DIR}.*" )
> if( NOT ${SOURCE_FOLDER} MATCHES "NOTFOUND" )
> #message( "err folder : ${SOURCE_FOLDER} " )
> SOURCE_GROUP( ${SOURCE_FOLDER} FILES ${SOURCE} )
> SOURCE_GROUP( ${SOURCE_FOLDER} FILES ${CMAKE_BINARY_DIR}/${BASENAME}${FILEEXT}
> )
> endif()
> add_custom_command( OUTPUT ${CMAKE_BINARY_DIR}/${
> BASENAME}${FILEEXT}
> DEPENDS ${SOURCE}
> COMMAND ${CMAKE_COMMAND} -E
> copy_if_different ${SOURCE} ${CMAKE_BINARY_DIR}/${BASENAME}${FILEEXT}
> #COMMAND ${CMAKE_COMMAND} -E touch
> ${CMAKE_BINARY_DIR}/${BASENAME}${FILEEXT}
> )
> #EXECUTE_PROCESS(COMMAND cmake -E copy_if_different ${SOURCE}
> ${CMAKE_BINARY_DIR}/${BASENAME}${FILEEXT} )
>
> else( ${SOURCE} MATCHES "^${PROJECT_SOURCE_DIR}.*" )
> if( NOT ${SOURCE_FOLDER} MATCHES "NOTFOUND" )
> #message( "err folder : ${SOURCE_FOLDER} " )
> SOURCE_GROUP( ${SOURCE_FOLDER} FILES ${PROJECT_SOURCE_DIR}/${SOURCE}
> )
> SOURCE_GROUP( ${SOURCE_FOLDER} FILES ${CMAKE_BINARY_DIR}/${BASENAME}${FILEEXT}
> )
> endif()
> add_custom_command( OUTPUT ${CMAKE_BINARY_DIR}/${
> BASENAME}${FILEEXT}
> DEPENDS ${PROJECT_SOURCE_DIR}/${SOURCE}
> COMMAND ${CMAKE_COMMAND} -E copy_if_different
> ${PROJECT_SOURCE_DIR}/${SOURCE} ${CMAKE_BINARY_DIR}/${BASENAME}${FILEEXT}
> #COMMAND ${CMAKE_COMMAND} -E touch
> ${CMAKE_BINARY_DIR}/${BASENAME}${FILEEXT}
> )
> #EXECUTE_PROCESS(COMMAND cmake -E copy_if_different
> ${PROJECT_SOURCE_DIR}/${SOURCE} ${CMAKE_BINARY_DIR}/${BASENAME}${FILEEXT}
> )
> #message( "LIB2_SOURCE2 : ${BASENAME} ${SOURCE}" )
> endif()
> set( ${FILE_LIST} ${${FILE_LIST}} ${CMAKE_BINARY_DIR}/${BASENAME}${FILEEXT}
> )
> #set( cplusplus_sources ${cplusplus_sources} ${CMAKE_BINARY_DIR}/${BASENAME}${FILEEXT}
> )
> else()
> #message( "NOT THING ${SOURCE}" )
> endif()
> ENDFOREACH(SOURCE)
> endmacro( COPY_CPLUSPLUS )
>
>
>
> On Wed, Jan 17, 2018 at 10:05 AM, Jimi Damon <jdamon at accesio.com> wrote:
>
>> Hi,
>>
>> I want to use Gtest for some unit tests on a number of the C functions
>> that comprise my C executable. However, Gtest ( And gMock ) are C++
>> testing frameworks.
>>
>> What I would like to have is a project for my exe and then a separate
>> project for my C++ library and be able to change the source properties to
>> use the language CXX just before compiling.
>>
>> The problem I'm having is that CMake uses the CXX compiler for the C
>> files.
>>
>>
>> Here's what I would like to have
>>
>> project(cexe)
>> set(SOURCES foo.c bar.c )
>> add_executable( cexe ${SOURCES} )
>>
>> project(cpplib)
>> set_source_files_properties(${SOURCES} PROPERTIES LANGUAGE CXX )
>> add_library( cpplib SHARED ${SOURCES} )
>>
>>
>>
>> Is there a way to do this ?
>>
>> Can target_compile_options set the compile type for a given target ?
>>
>>
>> In the past I've had to copy the .C files to some renamed .CPP equivalent
>> and then compile off of that.
>>
>> I'm hoping that enough new functionality has been added to Cmake to allow
>> separation between compiles.
>>
>>
>> Thanks,
>>
>>
>>
>>
>> --
>>
>> Jimi Damon
>> ACCES I/O Products, Inc.
>> <http://accesio.com/go.cgi?p=/contact/contact.html>
>> Linux Engineer
>> JDamon at accesio.com
>> (858) 550-7320 x3015
>> [image: ACCES I/O Logo]
>> 10623 Roselle Street San Diego CA 92121-1506 <http://accesio.com/>
>>
>>
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>
> --
>
> Powered by www.kitware.com
>
> Please keep messages on-topic and check the CMake FAQ at:
> http://www.cmake.org/Wiki/CMake_FAQ
>
> Kitware offers various services to support the CMake community. For more
> information on each offering, please visit:
>
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> CMake Consulting: http://cmake.org/cmake/help/consulting.html
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>
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