Re: [PATCH v5 6/8] cmake: support for building git on windows with mingw

[Sibi Siddharthan <sibisiddharthan.github@gmail.com>]

This module should not be used here as Git is built with pthreads in mind.
All of the Linux systems have the pthread library at install. For
Windows, there is a pthread layer implemented using Win32 calls in
compat/win32/pthread.c,h .

It would be nice if the library checks for pthreads on Windows
(libwinpthread and similar implementations), but it does not.

Thank You,
Sibi Siddharthan

On Tue, Jun 30, 2020 at 12:55 PM David Aguilar <davvid@gmail.com> wrote:
>
> On Fri, Jun 26, 2020 at 04:11:36PM +0000, Sibi Siddharthan via GitGitGadget wrote:
> > From: Sibi Siddharthan <sibisiddharthan.github@gmail.com>
> >
> > This patch facilitates building git on Windows with CMake using MinGW
> >
> > NOTE: The funtions unsetenv and hstrerror are not checked in Windows
> > builds.
> > Reasons
> > NO_UNSETENV is not compatible with Windows builds.
> > lines 262-264 compat/mingw.h
> >
> > compat/mingw.h(line 25) provides a definition of hstrerror which
> > conflicts with the definition provided in
> > git-compat-util.h(lines 733-736).
> >
> > To use CMake on Windows with MinGW do this:
> > cmake `relative-path-to-srcdir` -G "MinGW Makefiles"
> >
> > Signed-off-by: Sibi Siddharthan <sibisiddharthan.github@gmail.com>
> > ---
> >  contrib/buildsystems/CMakeLists.txt | 117 ++++++++++++++++++++++------
> >  1 file changed, 94 insertions(+), 23 deletions(-)
> >
> > diff --git a/contrib/buildsystems/CMakeLists.txt b/contrib/buildsystems/CMakeLists.txt
> > index 2768ee5b71..2d7c0ed88e 100644
> > --- a/contrib/buildsystems/CMakeLists.txt
> > +++ b/contrib/buildsystems/CMakeLists.txt
> > @@ -42,6 +42,10 @@ cmake_minimum_required(VERSION 3.14)
> >  set(CMAKE_SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/../..)
> >
> >  find_program(SH_EXE sh)
> > +if(NOT SH_EXE)
> > +     message(FATAL_ERROR "sh: shell interpreter was not found in your path, please install one."
> > +                     "On Windows, you can get it as part of 'Git for Windows' install at https://gitforwindows.org/")
> > +endif()
> >
> >  #Create GIT-VERSION-FILE using GIT-VERSION-GEN
> >  if(NOT EXISTS ${CMAKE_SOURCE_DIR}/GIT-VERSION-FILE)
> > @@ -65,7 +69,9 @@ project(git
> >       VERSION ${git_version}
> >       LANGUAGES C)
> >
> > +
> >  #TODO gitk git-gui gitweb
> > +#TODO Enable NLS on windows natively
> >  #TODO Add pcre support
> >
> >  #macros for parsing the Makefile for sources and scripts
> > @@ -104,6 +110,7 @@ find_package(EXPAT)
> >  find_package(Iconv)
> >  find_package(Intl)
> >
> > +
> >  if(NOT Intl_FOUND)
> >       add_compile_definitions(NO_GETTEXT)
> >       if(NOT Iconv_FOUND)
> > @@ -125,6 +132,14 @@ if(Intl_FOUND)
> >       include_directories(SYSTEM ${Intl_INCLUDE_DIRS})
> >  endif()
> >
> > +
> > +if(WIN32)
> > +     find_program(WINDRES_EXE windres)
> > +     if(NOT WINDRES_EXE)
> > +             message(FATAL_ERROR "Install windres on Windows for resource files")
> > +     endif()
> > +endif()
> > +
> >  find_program(MSGFMT_EXE msgfmt)
> >  if(NOT MSGFMT_EXE)
> >       message(WARNING "Text Translations won't be build")
> > @@ -156,11 +171,35 @@ add_compile_definitions(PAGER_ENV="LESS=FRX LV=-c"
> >                       BINDIR="bin"
> >                       GIT_BUILT_FROM_COMMIT="")
> >
> > -set(FALLBACK_RUNTIME_PREFIX /home/$ENV{USER})
> > -add_compile_definitions(FALLBACK_RUNTIME_PREFIX="${FALLBACK_RUNTIME_PREFIX}")
> > +if(WIN32)
> > +     set(FALLBACK_RUNTIME_PREFIX /mingw64)
> > +     add_compile_definitions(FALLBACK_RUNTIME_PREFIX="${FALLBACK_RUNTIME_PREFIX}")
> > +else()
> > +     set(FALLBACK_RUNTIME_PREFIX /home/$ENV{USER})
> > +     add_compile_definitions(FALLBACK_RUNTIME_PREFIX="${FALLBACK_RUNTIME_PREFIX}")
> > +endif()
> > +
> > +
> > +#Platform Specific
> > +if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
> > +     include_directories(${CMAKE_SOURCE_DIR}/compat/win32)
> > +     add_compile_definitions(HAVE_ALLOCA_H NO_POSIX_GOODIES NATIVE_CRLF NO_UNIX_SOCKETS WIN32
> > +                             _CONSOLE DETECT_MSYS_TTY STRIP_EXTENSION=".exe"  NO_SYMLINK_HEAD UNRELIABLE_FSTAT
> > +                             NOGDI OBJECT_CREATION_MODE=1 __USE_MINGW_ANSI_STDIO=0
> > +                             USE_NED_ALLOCATOR OVERRIDE_STRDUP MMAP_PREVENTS_DELETE USE_WIN32_MMAP
> > +                             UNICODE _UNICODE HAVE_WPGMPTR ENSURE_MSYSTEM_IS_SET)
> > +     list(APPEND compat_SOURCES compat/mingw.c compat/winansi.c compat/win32/path-utils.c
> > +             compat/win32/pthread.c compat/win32mmap.c compat/win32/syslog.c
> > +             compat/win32/trace2_win32_process_info.c compat/win32/dirent.c
> > +             compat/nedmalloc/nedmalloc.c compat/strdup.c)
> > +     set(NO_UNIX_SOCKETS 1)
> > +
> > +elseif(CMAKE_SYSTEM_NAME STREQUAL "Linux")
> > +     add_compile_definitions(PROCFS_EXECUTABLE_PATH="/proc/self/exe" HAVE_DEV_TTY )
> > +     list(APPEND compat_SOURCES unix-socket.c)
> > +endif()
> >
> > -add_compile_definitions(PROCFS_EXECUTABLE_PATH="/proc/self/exe" HAVE_DEV_TTY )
> > -list(APPEND compat_SOURCES unix-socket.c)
> > +set(EXE_EXTENSION ${CMAKE_EXECUTABLE_SUFFIX})
> >
> >  #header checks
> >  check_include_file(libgen.h HAVE_LIBGEN_H)
> > @@ -223,7 +262,12 @@ endif()
> >  #function checks
> >  set(function_checks
> >       strcasestr memmem strlcpy strtoimax strtoumax strtoull
> > -     setenv mkdtemp poll pread memmem unsetenv hstrerror)
> > +     setenv mkdtemp poll pread memmem)
> > +
> > +#unsetenv,hstrerror are incompatible with windows build
> > +if(NOT WIN32)
> > +     list(APPEND function_checks unsetenv hstrerror)
> > +endif()
> >
> >  foreach(f ${function_checks})
> >       string(TOUPPER ${f} uf)
> > @@ -444,7 +488,13 @@ unset(CMAKE_REQUIRED_INCLUDES)
> >  #programs
> >  set(PROGRAMS_BUILT
> >       git git-bugreport git-credential-store git-daemon git-fast-import git-http-backend git-sh-i18n--envsubst
> > -     git-shell git-remote-testsvn git-credential-cache git-credential-cache--daemon)
> > +     git-shell git-remote-testsvn)
> > +
> > +if(NO_UNIX_SOCKETS)
> > +     list(APPEND excluded_progs git-credential-cache git-credential-cache--daemon)
> > +else()
> > +     list(APPEND PROGRAMS_BUILT git-credential-cache git-credential-cache--daemon)
> > +endif()
> >
> >  if(NOT CURL_FOUND)
> >       list(APPEND excluded_progs git-http-fetch git-http-push)
> > @@ -516,15 +566,34 @@ parse_makefile_for_sources(libvcs-svn_SOURCES "VCSSVN_OBJS")
> >  list(TRANSFORM libvcs-svn_SOURCES PREPEND "${CMAKE_SOURCE_DIR}/")
> >  add_library(vcs-svn STATIC ${libvcs-svn_SOURCES})
> >
> > +#add git.rc for gcc
> > +if(WIN32)
> > +     add_custom_command(OUTPUT ${CMAKE_BINARY_DIR}/git.res
> > +                     COMMAND ${WINDRES_EXE} -O coff -DMAJOR=${PROJECT_VERSION_MAJOR} -DMINOR=${PROJECT_VERSION_MINOR}
> > +                             -DMICRO=${PROJECT_VERSION_PATCH} -DPATCHLEVEL=0 -DGIT_VERSION="\\\"${PROJECT_VERSION}.GIT\\\""
> > +                             -i ${CMAKE_SOURCE_DIR}/git.rc -o ${CMAKE_BINARY_DIR}/git.res
> > +                     WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
> > +                     VERBATIM)
> > +     add_custom_target(git-rc DEPENDS ${CMAKE_BINARY_DIR}/git.res)
> > +endif()
> > +
> >  #link all required libraries to common-main
> >  add_library(common-main OBJECT ${CMAKE_SOURCE_DIR}/common-main.c)
> > -target_link_libraries(common-main libgit xdiff ${ZLIB_LIBRARIES} pthread rt)
> > +
> > +target_link_libraries(common-main libgit xdiff ${ZLIB_LIBRARIES})
> >  if(Intl_FOUND)
> >       target_link_libraries(common-main ${Intl_LIBRARIES})
> >  endif()
> >  if(Iconv_FOUND)
> >       target_link_libraries(common-main ${Iconv_LIBRARIES})
> >  endif()
> > +if(WIN32)
> > +     target_link_libraries(common-main ws2_32 ntdll ${CMAKE_BINARY_DIR}/git.res)
> > +     add_dependencies(common-main git-rc)
> > +     target_link_options(common-main PUBLIC -municode -Wl,--nxcompat -Wl,--dynamicbase -Wl,--pic-executable,-e,mainCRTStartup)
> > +elseif(UNIX)
> > +     target_link_libraries(common-main pthread rt)
> > +endif()
>
>
> Small note about pthread.  In CMake land, the typical convention is to
> use the FindThreads module. [1]
>
> To use it, add this to the top-level:
>
>         set(THREADS_PREFER_PTHREAD_FLAG TRUE)
>         find_package(Threads REQUIRED)
>
> and then use the Threads::Threads target with target_link_libraries()
> instead of hard-coding "pthread" here.
>
> That way it'll only use the "-pthread" flag and library links as needed.
>
> I'm not sure if mingw makes this advice moot, but I figured it was worth
> mentioning.
>
> [1] https://cmake.org/cmake/help/latest/module/FindThreads.html
> --
> David