Windows cmake build fails

[Katharsas]

When i go into g3log dir and try:

mkdir build
cd build
cmake ../ -DCMAKE_BUILD_TYPE=Release -G "Visual Studio 15"

cmake (latest version 3.14.1 win64) fails with

CMake Error at CMakeLists.txt:95 (math):
  math cannot parse the expression: "/255": syntax error, unexpected
  exp_DIVIDE, expecting exp_PLUS or exp_MINUS or exp_OPENPARENT or exp_NUMBER
  (1).

CMake Error at CMakeLists.txt:96 (math):
  math cannot parse the expression: "%255": syntax error, unexpected exp_MOD,
  expecting exp_PLUS or exp_MINUS or exp_OPENPARENT or exp_NUMBER (1).

for g3log commits at tag 1.3.1, 1.3.2 and current master (9c5e7f3). When i go back to 1.3, it seems to work. This seems to be the case for both cmd and powershell.

[KjellKod]

Hi,

Your environment does not seem to find git. It's the only way I've found to easily extract the software version without hardcoding into a file a version. (Ugh!)

SET(MAJOR_VERSION 1)
IF ( NOT VERSION )
   IF ( "${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Windows" )
      message("windows: Extracting git software version")
      execute_process(COMMAND cmd /c "git rev-list --branches HEAD | find /v " " /c" OUTPUT_VARIABLE GIT_VERSION WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
   ELSE()
      IF(UNIX OR ${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
         message( STATUS "nix: Extracting git software version" )
      ELSE()
         message( STATUS "unknown platform: extracting git software version" )
      ENDIF()
      execute_process(COMMAND bash "-c" "git rev-list --branches HEAD | wc -l | tr -d ' ' | tr -d '\n'" OUTPUT_VARIABLE GIT_VERSION WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
   ENDIF()

   SET(MINOR_VERSION 3)
   math(EXPR VERSION-BASE ${GIT_VERSION}/255)
   math(EXPR VERSION-REMAINDER ${GIT_VERSION}%255)

Suggestions:

1. Make sure your environment is setup so the path works for accessing git.
2. You can also, I believe, pass in, GIT_VERSION with the GIT_VERSION configuration. You can either set the GIT_VERSION to whatever.

[KjellKod]

A third option could be to change the CMakeLists.txt to check if the value GIT_VERSION isn't set and then just set it to a default value 1 or similar. If you take this route then I think that could be a nice adjustment to the CMakeLists.txt file -- if so, please do a pull request

[Katharsas]

I'm new to cpp and cmake so i kind of have a hard time understanding what is going on in these cmake statements. I assume GIT_VERSION is version of git that is called (but how is it used) ? I don't really understand options 2 & 3.

I don't have git on my path because it is not installed, so i should probably do that first. It is not installed because i am using SourceTree as my git client, which comes with its own bundled git binaries. I guess bundling Git is quite popular for windows git clients, so it would probably a good idea to
A) mention the need for Git on path somewhere in the readme (i could do that) and
B) checking during cmake on windows if Git is available on path and emitting a descriptive error if not (that would be very very hard for me, if this is even possible)

(Personally i just change hardcoded version on release with a separate commit in my projects, it helps documenting versions without being mutable like tags^^)

Edit:
Any way, installing Git to path fixed the problem, thanks. Tell me if you'd like to have pull request on documentation.

[KjellKod]

GIT_VERSION is not the version of git is the version of the g3log software

[KjellKod]

I.e. git retrieved version

[Katharsas]

Oh ok, now option 2 and 3 make much more sense. I'll see what i can do.

[KjellKod]

@Katharsas can this be closed?

[macdew]

I faced a similar issue today whilst rebuilding the source from the github release tar.gz file. I solved it by just passing -DVERSION=1.3.2 to the CMake command. This bypasses the git version check and I did not see any negative outcomes.

[KjellKod]

perfect. I just updated the doc and I consider this issue closed now: #316

[KjellKod]

@macdew thanks