Changes to support Mac OSX

[grantsloman]

A few changes for building & running on Mac OSX. WxWidgets tutorials 1 & 2 now build and run successfully. Further work is required to get wxMidi working for tutorials 3 & 4.

Also a few general Unix fixes for copying target libs & creating symbolic link.

[cecilios]

Policy CMP0078 was defined in CMake version 3.13. As the minimum required version for building lomse is 2.8.10, any version lower than 3.13 generates an error:

CMake Error at CMakeLists.txt:208 (cmake_policy):
  Policy "CMP0087" is not known to this version of CMake.

Please change to:

if (${CMAKE_VERSION} GREATER "3.12")
    cmake_policy(SET CMP0078 NEW)
endif()

[grantsloman]

Done

[grantsloman]

Done

[dmitrio95]

It seems you have added CMP0087 first and later changed it to CMP0078?

Anyway, if your changes require the new behavior for this policy (namely, generator expressions support for install), wouldn't this break things for earlier versions of CMake which don't have support for this feature included?

[grantsloman]

In my change I've kept it as CMP0087 - expecting that 78 was a typo intended to be 87.

If I remember correctly, I only added that to prevent a warning so might not be critical.

[cecilios]

@dmitrio95 You are right! I overlooked that a generator expression was introduced. I'm going to test this PR with cmake < 3.14 and also investigate the issue of the symlink commented by @grantsloman

[cecilios]

PR tested. When using cmake version 3.10.2, as expected, the generator expression is not evaluated and the resulting command is

ln -fs /usr/local/lib/$<TARGET_FILE_NAME:lomse-shared> /usr/lib/liblomse.so

and fails to create the symlink. So it is clear that CMP0087 NEW behavior is not acceptable unless forcing to require a cmake >= 3.14

@grantsloman To try understand why the unpatched CMakeLists.txt failed to create the symlink in macOS it would be useful to look at the generated command. And this is simple because in build folder cmake generates a file named "cmake_install.cmake". Please open it with a text editor and look for string "EXECUTE_PROCESS(COMMAND ln -fs". There is only one occurrence, around line 78, e.g. (when using cmake 3.10.2):

  EXECUTE_PROCESS(COMMAND ln -fs /usr/local/lib/$<TARGET_FILE_NAME:lomse-shared> 
                                        /usr/local/lib/liblomse.so )

There you will see the ln command and its arguments and you can try to find why it does not work for you.

[cecilios]

@grantsloman
A posible solution to supress fatal: No names found, cannot describe anything. message is to add ERROR_QUIET parameter to execute_command:

    execute_process(COMMAND "${GIT_EXECUTABLE}" describe --tags --long --dirty
      WORKING_DIRECTORY "${LOMSE_ROOT_DIR}"
      OUTPUT_VARIABLE LOMSE_VERSION_GIT
      OUTPUT_STRIP_TRAILING_WHITESPACE
      ERROR_QUIET)

I have tested and it works.

[grantsloman]

If I change the CMakeLists.txt line back to

"EXECUTE_PROCESS(COMMAND ln -fs ${CMAKE_INSTALL_PREFIX}/lib/${LOMSE_SHARED} 
                                        ${CMAKE_INSTALL_PREFIX}/lib/liblomse.so )" 

then the resulting generated command in cmake_install.cmake is

EXECUTE_PROCESS(COMMAND ln -fs /usr/local/lib/lomse-shared 
                                        /usr/local/lib/liblomse.so )

which isn't the correct target file name.

[cecilios]

I've done some tests and, curiously, the symlink is always created even when removing these lines:

    #create symlink to library
	install( CODE
        "EXECUTE_PROCESS(COMMAND ln -fs ${CMAKE_INSTALL_PREFIX}/lib/${LOMSE_SHARED} 
                                        ${CMAKE_INSTALL_PREFIX}/lib/liblomse.so )" 
    )

Therefore it seems irrelevant if that command is correct or not, and can be removed.

It looks as if cmake automatically creates the library and the symlink at build time. You can find them in build folder. Please notice that the previous command does not create a symlink in build folder so it is automatically created by cmake. And both are copied to /usr/local/lib at install time, and the symlink is adjusted to point to the installed library.

I have tested removing the previous lines from CMakeLists.txt and it works perfectly and the symlink is created at installation time.

I'm not been able to find any cmake documentation explaining this and confirming that symlinks are automatically created for libraries, but my tests suggest this. I am missing something?

@grantsloman Could you please test this, removing previous lines, in macOS?