Re: [Tarantool-patches] [PATCH luajit 2/5] build: replace GNU Make with CMake

[Timur Safin via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

LGTM, if you need a shorter answer, but there are some further comments below...


: From: Igor Munkin <imun@tarantool.org>
: Subject: Re: [PATCH luajit 2/5] build: replace GNU Make with CMake
: 
: > : +
: > : +# CMake generated artefacts
: > : +CMakeCache.txt
: > : +CMakeFiles
: > : +Makefile
: > : +cmake_install.cmake
: > : +compile_commands.json
: > : +install_manifest.txt
: > : +luajit-parse-memprof
: > : +luajit.pc
: >
: > Uh-oh, this ugly hack would be handled by single exclusion
: > build*/
: > if we would all use the same (idiomatic) approach for out-of-source
: > build. But we do not yet accustomed to that, so... never mind!
: 
: I personally prefer mechanisms to policies: this approach allows one to
: freely name so called <build> directory on his own e.g. <bindir>,
: <tuta-lejit-sborka>, or even <qkrq>, that is my favourite one.
: Furthermore this approach allows to ignore CMake output for both
: out-of-source and in-source build. Such configuration is much more
: flexible, IMHO, and leads to a neglible and well localized changes in
: .gitignore. But, nevermind ;)

Ok, most of those names are generic enough as generated by cmake,
so it's a good idea to exclude them. 
...
: 
: > : +
: > : +# Switch to harder (and slower) hash function when a collision
: > : +# chain in the string hash table exceeds certain length.
: > : +option(LUAJIT_SMART_STRINGS "Harder string hashing function" ON)
: > : +if(LUAJIT_SMART_STRINGS)
: > : +  AppendFlags(TARGET_C_FLAGS -DLUAJIT_SMART_STRINGS=1)
: > : +endif()
: >
: > The same note about lack of ENABLE prefix in the option name.
: 
: Well, again: we do care about consistency. Unfortunately, this option is
: provided only in our fork, so the inconsistency you're talking about was
: messed up years ago. I propose to port the build system as is now with
: no changes in the option names, but this is a nice point to refactor
: them and make them consistent in scope of a separate issue. Thoughts?

Ok, then leave them as is. This patchset supposed to be refactoring of 
what is already there. 
...
: >
: > FWIW -msse2 implicitly assumes -msse but if that way it used to be
: > in makefiles than so be it. Don't need to "improve" it.
: 
: Yes, I tried to move everything making as few changes as possible. I believe
: there are lots of places to be "modernized" later.

Yup, we should leave it as is today.
...
: 
: >
: > : +
: > : +include(SetTargetFlags)
: > : +list(APPEND TARGET_LIBS m)
: >
: > ${TARGET_LIBS} below used as space separated list of words, it's probably
: > bad idea to operate with it as list, because we end up in trace with
: something
: > like
: >
: >   ./third_party/luajit/src/CMakeLists.txt(302):
: target_include_directories(luajit_static PRIVATE
: ./build/third_party/luajit/src )
: >   ./third_party/luajit/src/CMakeLists.txt(305):
: target_link_libraries(luajit_static libluajit_static dl;m )
: >
: 
: Hm, I'm not quite sure what is broken by such usage, but everything is
: OK when I run <make> with VERBOSE=1. Here is the related part:
: | $ make VERBOSE=1
: | <...>
: | [100%] Linking C executable luajit
: | cd /tarantool-luajit/src && /usr/bin/cmake -E cmake_link_script
: CMakeFiles/luajit_static.dir/link.txt --verbose=1
: | /usr/bin/cc  -fomit-frame-pointer -fno-stack-protector -Wall  -rdynamic  -
: Wl,-E CMakeFiles/luajit_static.dir/luajit.c.o  -o luajit  libluajit.a -ldl -
: lm
: | make[2]: Leaving directory '/tarantool-luajit'
: | [100%] Built target luajit_static
: | <...>

Ok then, that's probably means that target_link_libraries() is expecting list 
at that place, and this works as expected. So, never mind. 
...
: >
: > Here we have reasonable cmake complain:
: >
: >   -- Configuring done
: >   WARNING: Target "luajit_static" has EXCLUDE_FROM_ALL set and will not be
: built by default but
: >   an install rule has been provided for it.  CMake does not define
: behavior for this case.
: >   WARNING: Target "libluajit_static" has EXCLUDE_FROM_ALL set and will not
: be built by default
: >   but an install rule has been provided for it.  CMake does not define
: behavior for this case.
: >
: 
: Well, I have no warning at all on my machine...

It's cmake 3.13.4 here, may be warning is version dependent. 

: | $ cmake .
: | -- The C compiler identification is GNU 8.3.0
: | -- Check for working C compiler: /usr/bin/cc
: | -- Check for working C compiler: /usr/bin/cc -- works
: | -- Detecting C compiler ABI info
: | -- Detecting C compiler ABI info - done
: | -- Detecting C compile features
: | -- Detecting C compile features - done
: | -- [SetVersion] Reading version from VCS: v2.1.0-beta3-79-ge616d62
: | -- The ASM compiler identification is GNU
: | -- Found assembler: /usr/bin/cc
: | -- Configuring done
: | -- Generating done
: | -- Build files have been written to: /tarantool-luajit
: 
: > There is no much point to install ${LIBLUAJIT_STATIC_DEPS} or
: ${LIBLUAJIT_SHARED_DEPS} if we have
: > excluded luajit_static and/or libluajit_shared from target all
: dependencies via EXCLUDE_FROM_ALL.
: 
: ... however, I looked to the docs[2] and there is mentioned the fact
: such behaviour is not defined and user is responsible to ensure whether
: the corresponding artefacts are built prior to installing them. I
: believed this machinery can be done on CMake side, but I forgot that
: CMake is a crap. Wrapped all install rules with if/endif, squashed,
: force-pushed to the branch. Diff is below:
: 
: ============================================================================
: ====
: 
: diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
: index 5724c8b..51e97a6 100644
: --- a/src/CMakeLists.txt
: +++ b/src/CMakeLists.txt
: @@ -338,21 +338,35 @@ set(LUAJIT_BINARY $<TARGET_FILE:${LUAJIT_DEPS}>
: PARENT_SCOPE)
:  add_custom_target(libluajit DEPENDS ${LIBLUAJIT_DEPS})
:  add_custom_target(luajit ALL DEPENDS libluajit ${LUAJIT_DEPS})
: 
: -install(TARGETS ${LUAJIT_DEPS}
: -  RUNTIME
: -  DESTINATION bin
: -  COMPONENT luajit
: -)
: -install(TARGETS ${LIBLUAJIT_STATIC_DEPS}
: -  ARCHIVE
: -  DESTINATION lib
: -  COMPONENT luajit
: -)
: -install(TARGETS ${LIBLUAJIT_SHARED_DEPS}
: -  LIBRARY
: -  DESTINATION lib
: -  COMPONENT luajit
: -)
: +# Unfortunately, CMake provides no guarantees for install commands
: +# used for the targets excluded from <all> and obligues user to
: +# handle this manually on his side. Hence check whether the
: +# targets used below are presented for the chosen build mode.
: +# See more info in CMake docs below:
: +# https://cmake.org/cmake/help/v3.1/prop_tgt/EXCLUDE_FROM_ALL.html
: +if(TARGET ${LUAJIT_DEPS})
: +  install(TARGETS ${LUAJIT_DEPS}
: +    RUNTIME
: +    DESTINATION bin
: +    COMPONENT luajit
: +  )
: +endif()
: +
: +if(TARGET ${LIBLUAJIT_STATIC_DEPS})
: +  install(TARGETS ${LIBLUAJIT_STATIC_DEPS}
: +    ARCHIVE
: +    DESTINATION lib
: +    COMPONENT luajit
: +  )
: +endif()
: +
: +if(TARGET ${LIBLUAJIT_SHARED_DEPS})
: +  install(TARGETS ${LIBLUAJIT_SHARED_DEPS}
: +    LIBRARY
: +    DESTINATION lib
: +    COMPONENT luajit
: +  )
: +endif()

Noice!


Best Regards,
Timur