[CMake] getting compiler's include paths

jl forums jlmxyz.forums at gmail.com
Sun Jul 21 18:54:29 EDT 2019 

lol.... c++20 modules 😂🙄 IF users use them.... modules is just pain in
the ass for developers.... I hope that real developers will simply ignore
them.... headers are here for a good reason, and stupid languages like
python that use modules are just.... stupid.... it will make more
complicated for the developer to track dependencies, understand how the
software is build.... or create system breakages (what if a C define
change????)... instead of having a clean header which describes the API
with comments, you get a raw processed? well that's sure an "improvement"...
and you, you wants to "fix" this issue by dropping the dependency scanner
🤣 ok.... i begin to think to not have chosen the right makefile
generator....
I hope you revise your mind and write a fix
thanks and regards

Le jeu. 18 juil. 2019 à 20:40, Robert Maynard <robert.maynard at kitware.com>
a écrit :

> The history behind the makefile generator and the custom dependency
> tracking logic was that it was written before
> the majority of compilers offered a robust way to generate the list of
> header dependencies.
>
> As it stands now we want to remove all this custom dependency scanning
> logic, not extend it to understand system headers
> ( As the naive approach would cause CMake to parse system headers, and
> slow down even more ). Luckily, C++20 modules
> also require us to drop the custom dependency scanning, so when we add
> C++20 module support to the Makefile generator
> this issue will be fixed as by product.
>
> On Wed, Jul 3, 2019 at 10:51 AM Robert Maynard
> <robert.maynard at kitware.com> wrote:
> >
> > 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:
> > >> >
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