[CMake] getting compiler's include paths

Robert Maynard robert.maynard at kitware.com
Wed Jul 10 08:57:58 EDT 2019 

I am not an user of ctags. But CMake supports generating a
`compile_commands.json` for the Makefile and Ninja generator (
https://cmake.org/cmake/help/latest/variable/CMAKE_EXPORT_COMPILE_COMMANDS.html
). That will have all the include directories for each target.

On Sun, Jul 7, 2019 at 10:27 AM jl forums <jlmxyz.forums at gmail.com> wrote:
>
> ok, thanks
> by the way what about my ctags rule? how can i get the include path of an app? so that i can pass it to ctags and have my tags produced?
> thanks and regards
> jlm
>
> Le mer. 3 juil. 2019 à 16:52, Robert Maynard <robert.maynard at kitware.com> a écrit :
>>
>> I completely forgot that the Makefiles based generators in CMake have
>> a separate heuristic for determining system headers.
>>
>> If you use the Ninja generator I see the expected behavior:
>> ~/W/t/nbuild $ sudo touch /usr/include/c++/7/array
>> ~/W/t/nbuild $ ninja -d explain -v
>> ninja explain: output test/CMakeFiles/ProjTest.dir/test.cpp.o older
>> than most recent input /usr/include/c++/7/array (1562165327 vs
>> 1562165329)
>> ninja explain: test/CMakeFiles/ProjTest.dir/test.cpp.o is dirty
>> ninja explain: test/ProjTest is dirty
>> [1/2] /usr/bin/c++   -I../my_lib/include -std=gnu++1z -MD -MT
>> test/CMakeFiles/ProjTest.dir/test.cpp.o -MF
>> test/CMakeFiles/ProjTest.dir/test.cpp.o.d -o
>> test/CMakeFiles/ProjTest.dir/test.cpp.o -c ../test/test.cpp
>> [2/2] : && /usr/bin/c++     test/CMakeFiles/ProjTest.dir/test.cpp.o
>> -o test/ProjTest   && :
>>
>>
>> I will need to spend some more time figuring out the extra include
>> caching logic for the Makefile based generators, and will report back.
>>
>> On Thu, Jun 27, 2019 at 8:59 AM jl forums <jlmxyz.forums at gmail.com> wrote:
>> >
>> > thanks for the anwer....
>> > quite not... I'm using cmake 3.14.2 (so, far away from 3.6....) and have a look, in main.cpp, there is #include <filesystem>:
>> >
>> > $ find /usr/include/ -name filesystem
>> > /usr/include/c++/5/experimental/filesystem
>> > /usr/include/c++/7/experimental/filesystem
>> > /usr/include/c++/8/filesystem
>> > /usr/include/c++/8/experimental/filesystem
>> > $ sudo touch /usr/include/c++/5/experimental/filesystem /usr/include/c++/7/experimental/filesystem /usr/include/c++/8/filesystem /usr/include/c++/8/experimental/filesystem
>> > $ make
>> > [100%] Built target FileSync
>> > $ touch ../main.cxx
>> > $ make
>> > Scanning dependencies of target FileSync
>> > [ 50%] Building CXX object CMakeFiles/FileSync.dir/main.cxx.o
>> > [100%] Linking CXX executable FileSync
>> > [100%] Built target FileSync
>> >
>> >
>> > => cmake don't create "full include dependency" which IS a mistake.... updating system g++ can just assume the target is uptodate and in fact just create a broken build...
>> >
>> > in cmake cxx.includecache
>> >
>> > #IncludeRegexLine: ^[ ]*[#%][ ]*(include|import)[ ]*[<"]([^">]+)([">])
>> > #IncludeRegexScan: ^.*$
>> > #IncludeRegexComplain: ^$
>> > #IncludeRegexTransform:
>> > /home/orange/crypt/Devel/projets/FileSync/main.cxx
>> > cstdio
>> > -
>> > io.h
>> > -
>> > fcntl.h
>> > -
>> > locale
>> > -
>> > clocale
>> > -
>> > fstream
>> > -
>> > iostream
>> > -
>> > filesystem
>> > -
>> >
>> > $ /usr/bin/gcc-8 -M ../main.cxx
>> > main.o: ../main.cxx /usr/x86_64-linux-gnu/include/stdc-predef.h \
>> >  /usr/include/c++/8/cstdio \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/c++config.h \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/os_defines.h \
>> >  /usr/x86_64-linux-gnu/include/features.h \
>> >  /usr/x86_64-linux-gnu/include/sys/cdefs.h \
>> >  /usr/x86_64-linux-gnu/include/bits/wordsize.h \
>> >  /usr/x86_64-linux-gnu/include/bits/long-double.h \
>> >  /usr/x86_64-linux-gnu/include/gnu/stubs.h \
>> >  /usr/x86_64-linux-gnu/include/gnu/stubs-64.h \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/cpu_defines.h \
>> >  /usr/x86_64-linux-gnu/include/stdio.h \
>> >  /usr/x86_64-linux-gnu/include/bits/libc-header-start.h \
>> >  /usr/lib/gcc/x86_64-linux-gnu/8/include/stddef.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types.h \
>> >  /usr/x86_64-linux-gnu/include/bits/typesizes.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/__FILE.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/FILE.h \
>> >  /usr/x86_64-linux-gnu/include/bits/libio.h \
>> >  /usr/x86_64-linux-gnu/include/bits/_G_config.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/__mbstate_t.h \
>> >  /usr/lib/gcc/x86_64-linux-gnu/8/include/stdarg.h \
>> >  /usr/x86_64-linux-gnu/include/bits/stdio_lim.h \
>> >  /usr/x86_64-linux-gnu/include/bits/sys_errlist.h \
>> >  /usr/include/c++/8/locale /usr/include/c++/8/bits/localefwd.h \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/c++locale.h \
>> >  /usr/include/c++/8/clocale /usr/x86_64-linux-gnu/include/locale.h \
>> >  /usr/x86_64-linux-gnu/include/bits/locale.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/locale_t.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/__locale_t.h \
>> >  /usr/include/c++/8/iosfwd /usr/include/c++/8/bits/stringfwd.h \
>> >  /usr/include/c++/8/bits/memoryfwd.h /usr/include/c++/8/bits/postypes.h \
>> >  /usr/include/c++/8/cwchar /usr/x86_64-linux-gnu/include/wchar.h \
>> >  /usr/x86_64-linux-gnu/include/bits/floatn.h \
>> >  /usr/x86_64-linux-gnu/include/bits/floatn-common.h \
>> >  /usr/x86_64-linux-gnu/include/bits/wchar.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/wint_t.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/mbstate_t.h \
>> >  /usr/include/c++/8/cctype /usr/x86_64-linux-gnu/include/ctype.h \
>> >  /usr/x86_64-linux-gnu/include/endian.h \
>> >  /usr/x86_64-linux-gnu/include/bits/endian.h \
>> >  /usr/x86_64-linux-gnu/include/bits/byteswap.h \
>> >  /usr/x86_64-linux-gnu/include/bits/byteswap-16.h \
>> >  /usr/x86_64-linux-gnu/include/bits/uintn-identity.h \
>> >  /usr/include/c++/8/bits/locale_classes.h /usr/include/c++/8/string \
>> >  /usr/include/c++/8/bits/char_traits.h \
>> >  /usr/include/c++/8/bits/stl_algobase.h \
>> >  /usr/include/c++/8/bits/functexcept.h \
>> >  /usr/include/c++/8/bits/exception_defines.h \
>> >  /usr/include/c++/8/bits/cpp_type_traits.h \
>> >  /usr/include/c++/8/ext/type_traits.h \
>> >  /usr/include/c++/8/ext/numeric_traits.h \
>> >  /usr/include/c++/8/bits/stl_pair.h /usr/include/c++/8/bits/move.h \
>> >  /usr/include/c++/8/bits/concept_check.h /usr/include/c++/8/type_traits \
>> >  /usr/include/c++/8/bits/stl_iterator_base_types.h \
>> >  /usr/include/c++/8/bits/stl_iterator_base_funcs.h \
>> >  /usr/include/c++/8/debug/assertions.h \
>> >  /usr/include/c++/8/bits/stl_iterator.h \
>> >  /usr/include/c++/8/bits/ptr_traits.h /usr/include/c++/8/debug/debug.h \
>> >  /usr/include/c++/8/bits/predefined_ops.h /usr/include/c++/8/cstdint \
>> >  /usr/lib/gcc/x86_64-linux-gnu/8/include/stdint.h \
>> >  /usr/x86_64-linux-gnu/include/stdint.h \
>> >  /usr/x86_64-linux-gnu/include/bits/stdint-intn.h \
>> >  /usr/x86_64-linux-gnu/include/bits/stdint-uintn.h \
>> >  /usr/include/c++/8/bits/allocator.h \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/c++allocator.h \
>> >  /usr/include/c++/8/ext/new_allocator.h /usr/include/c++/8/new \
>> >  /usr/include/c++/8/exception /usr/include/c++/8/bits/exception.h \
>> >  /usr/include/c++/8/bits/exception_ptr.h \
>> >  /usr/include/c++/8/bits/cxxabi_init_exception.h \
>> >  /usr/include/c++/8/typeinfo /usr/include/c++/8/bits/hash_bytes.h \
>> >  /usr/include/c++/8/bits/nested_exception.h \
>> >  /usr/include/c++/8/bits/ostream_insert.h \
>> >  /usr/include/c++/8/bits/cxxabi_forced.h \
>> >  /usr/include/c++/8/bits/stl_function.h \
>> >  /usr/include/c++/8/backward/binders.h \
>> >  /usr/include/c++/8/bits/range_access.h \
>> >  /usr/include/c++/8/initializer_list \
>> >  /usr/include/c++/8/bits/basic_string.h \
>> >  /usr/include/c++/8/ext/atomicity.h \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/gthr.h \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/gthr-default.h \
>> >  /usr/x86_64-linux-gnu/include/pthread.h \
>> >  /usr/x86_64-linux-gnu/include/sched.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/time_t.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/struct_timespec.h \
>> >  /usr/x86_64-linux-gnu/include/bits/sched.h \
>> >  /usr/x86_64-linux-gnu/include/bits/cpu-set.h \
>> >  /usr/x86_64-linux-gnu/include/time.h \
>> >  /usr/x86_64-linux-gnu/include/bits/time.h \
>> >  /usr/x86_64-linux-gnu/include/bits/timex.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/struct_timeval.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/clock_t.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/struct_tm.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/clockid_t.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/timer_t.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/struct_itimerspec.h \
>> >  /usr/x86_64-linux-gnu/include/bits/pthreadtypes.h \
>> >  /usr/x86_64-linux-gnu/include/bits/thread-shared-types.h \
>> >  /usr/x86_64-linux-gnu/include/bits/pthreadtypes-arch.h \
>> >  /usr/x86_64-linux-gnu/include/bits/setjmp.h \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/atomic_word.h \
>> >  /usr/include/c++/8/ext/alloc_traits.h \
>> >  /usr/include/c++/8/bits/alloc_traits.h \
>> >  /usr/include/c++/8/ext/string_conversions.h /usr/include/c++/8/cstdlib \
>> >  /usr/x86_64-linux-gnu/include/stdlib.h \
>> >  /usr/x86_64-linux-gnu/include/bits/waitflags.h \
>> >  /usr/x86_64-linux-gnu/include/bits/waitstatus.h \
>> >  /usr/x86_64-linux-gnu/include/sys/types.h \
>> >  /usr/x86_64-linux-gnu/include/sys/select.h \
>> >  /usr/x86_64-linux-gnu/include/bits/select.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/sigset_t.h \
>> >  /usr/x86_64-linux-gnu/include/bits/types/__sigset_t.h \
>> >  /usr/x86_64-linux-gnu/include/sys/sysmacros.h \
>> >  /usr/x86_64-linux-gnu/include/bits/sysmacros.h \
>> >  /usr/x86_64-linux-gnu/include/alloca.h \
>> >  /usr/x86_64-linux-gnu/include/bits/stdlib-float.h \
>> >  /usr/include/c++/8/bits/std_abs.h /usr/include/c++/8/cerrno \
>> >  /usr/x86_64-linux-gnu/include/errno.h \
>> >  /usr/x86_64-linux-gnu/include/bits/errno.h \
>> >  /usr/x86_64-linux-gnu/include/linux/errno.h \
>> >  /usr/x86_64-linux-gnu/include/asm/errno.h \
>> >  /usr/x86_64-linux-gnu/include/asm-generic/errno.h \
>> >  /usr/x86_64-linux-gnu/include/asm-generic/errno-base.h \
>> >  /usr/include/c++/8/bits/functional_hash.h \
>> >  /usr/include/c++/8/bits/basic_string.tcc \
>> >  /usr/include/c++/8/bits/locale_classes.tcc \
>> >  /usr/include/c++/8/bits/locale_facets.h /usr/include/c++/8/cwctype \
>> >  /usr/x86_64-linux-gnu/include/wctype.h \
>> >  /usr/x86_64-linux-gnu/include/bits/wctype-wchar.h \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/ctype_base.h \
>> >  /usr/include/c++/8/bits/ios_base.h /usr/include/c++/8/system_error \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/error_constants.h \
>> >  /usr/include/c++/8/stdexcept /usr/include/c++/8/streambuf \
>> >  /usr/include/c++/8/bits/streambuf.tcc \
>> >  /usr/include/c++/8/bits/streambuf_iterator.h \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/ctype_inline.h \
>> >  /usr/include/c++/8/bits/locale_facets.tcc \
>> >  /usr/include/c++/8/bits/locale_facets_nonio.h /usr/include/c++/8/ctime \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/time_members.h \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/messages_members.h \
>> >  /usr/x86_64-linux-gnu/include/libintl.h \
>> >  /usr/include/c++/8/bits/codecvt.h \
>> >  /usr/include/c++/8/bits/locale_facets_nonio.tcc \
>> >  /usr/include/c++/8/bits/locale_conv.h \
>> >  /usr/include/c++/8/bits/unique_ptr.h /usr/include/c++/8/utility \
>> >  /usr/include/c++/8/bits/stl_relops.h /usr/include/c++/8/tuple \
>> >  /usr/include/c++/8/array /usr/include/c++/8/bits/uses_allocator.h \
>> >  /usr/include/c++/8/bits/invoke.h /usr/include/c++/8/fstream \
>> >  /usr/include/c++/8/istream /usr/include/c++/8/ios \
>> >  /usr/include/c++/8/bits/basic_ios.h \
>> >  /usr/include/c++/8/bits/basic_ios.tcc /usr/include/c++/8/ostream \
>> >  /usr/include/c++/8/bits/ostream.tcc /usr/include/c++/8/bits/istream.tcc \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/basic_file.h \
>> >  /usr/include/x86_64-linux-gnu/c++/8/bits/c++io.h \
>> >  /usr/include/c++/8/bits/fstream.tcc /usr/include/c++/8/iostream \
>> >  /usr/include/c++/8/filesystem
>> >
>> >
>> > amazing, no? cmake find only 9 dependencies against 100+ real ones (and I don't even speak of errors that can be caused in parsing if some -D option is changed....
>> >
>> > thanks and regards
>> > JLM
>> >
>> >
>> > Le lun. 24 juin 2019 à 14:14, Robert Maynard <robert.maynard at kitware.com> a écrit :
>> >>
>> >> It look that starting with CMake 3.6 modification of system headers
>> >> will cause CMake to recompile projects. What version of CMake and your
>> >> compiler are you using?
>> >>
>> >> On Mon, Jun 17, 2019 at 9:40 AM jl forums <jlmxyz.forums at gmail.com> wrote:
>> >> >
>> >> > Hi,
>> >> > I want to create a full tag file and for this require to know the compiler full include path...  there is a way to had custom includes path but didn't found any variables for the include path....
>> >> > for example :
>> >> > $ gcc-8 -v -x c -E /dev/null
>> >> > Using built-in specs.
>> >> > [....]
>> >> > ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
>> >> > #include "..." search starts here:
>> >> > #include <...> search starts here:
>> >> >  /usr/lib/gcc/x86_64-linux-gnu/8/include
>> >> >  /usr/local/include
>> >> >  /usr/lib/gcc/x86_64-linux-gnu/8/include-fixed
>> >> >  /usr/x86_64-linux-gnu/include
>> >> >  /usr/include/x86_64-linux-gnu
>> >> >  /usr/include
>> >> > End of search list.
>> >> > [...]
>> >> >
>> >> > $ gcc -v -x c -E /dev/null
>> >> > Using built-in specs.
>> >> > [...]
>> >> > ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
>> >> > #include "..." search starts here:
>> >> > #include <...> search starts here:
>> >> >  /usr/lib/gcc/x86_64-linux-gnu/7/include
>> >> >  /usr/local/include
>> >> >  /usr/lib/gcc/x86_64-linux-gnu/7/include-fixed
>> >> >  /usr/x86_64-linux-gnu/include
>> >> >  /usr/include/x86_64-linux-gnu
>> >> >  /usr/include
>> >> > End of search list.
>> >> > [...]
>> >> >
>> >> > I tried to
>> >> >
>> >> >
>> >> > get_target_property(moggle_interface_includes FileSync INTERFACE_INCLUDE_DIRECTORIES)
>> >> > message("Moggle interface includes: ${moggle_interface_includes}")
>> >> >
>> >> > get_target_property(motor_includes FileSync INCLUDE_DIRECTORIES)
>> >> > message("MOTOR includes ${motor_includes}")
>> >> >
>> >> > but I get
>> >> >
>> >> > Moggle interface includes: moggle_interface_includes-NOTFOUND
>> >> > MOTOR includes motor_includes-NOTFOUND
>> >> >
>> >> >
>> >> > there is also some issue because cmake strip dependencies from system's include, which means that updating a system software won't cause rebuild and consider that the build is uptodate, causing unexpected results
>> >> > seems that there is ways to workaround this :  https://stackoverflow.com/questions/7461000/handling-header-files-dependencies-with-cmake but this is ugly... would be better to let the user choose with an option
>> >> >
>> >> > thanks and regards
>> >> > JLM
>> >> > --
>> >> >
>> >> > 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:
>> >> >
>> >> > CMake Support: http://cmake.org/cmake/help/support.html
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>> >> >
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