Put `.mod` files on `.gitignore`

[minhqdao]

Using the Modern Fortran plugin in VSCode, .mod files are continuously generated and I think it makes sense to exclude them from VC by adding them to .gitignore.

The .mod files in the example folders should also be excluded.

I think it also makes sense to also add them to the template for generating fpm packages.

[awvwgk]

.mod files should never be generated in source tree, this issue should be addressed in Modern Fortran to store the .mod files in a dedicated directory like done by other tools, e.g. fpm is using build/.

[awvwgk]

I recall that LFortran was not honoring the -J option passed by fpm when I first implemented support for it and instead stored the .mod files in the current working directory (see lfortran/lfortran#472). If you are using LFortran as linter in Modern Fortran this might be an LFortran issue rather than a Modern Fortran / VSCode issue.

[LKedward]

Thanks @minhqdao. As Sebastian has said, this is an issue with the vscode Modern Fortran plugin not with fpm. As a solution, I would recommend explicitly specifying a module directory to the Modern Fortran plugin:

{
  "fortran.linter.extraArgs" : [
    "-Jbuild" 
  ] 
} 

Alternatively, you could suggest a PR to the Modern Fortran plugin to make this the default for fpm projects.

[minhqdao]

Thanks @minhqdao. As Sebastian has said, this is an issue with the vscode Modern Fortran plugin not with fpm. As a solution, I would recommend explicitly specifying a module directory to the Modern Fortran plugin:

{
  "fortran.linter.extraArgs" : [
    "-Jbuild" 
  ] 
} 

Alternatively, you could suggest a PR to the Modern Fortran plugin to make this the default for fpm projects.

Thanks for the suggestion, @LKedward, but it seems that lfortran isn't able to find the build folder to write the .mod files in with the -Jbuild argument. I'll raise an issue there and put the .mod files in my global .gitignore while this isn't resolved.

[minhqdao]

Man, I don't know why I thought it was lfortran, but the compiler I'm using for linting is actually gfortran. Nevertheless, using the argument -J${workspaceFolder}/build puts .mod files in the build folder. But it only works if the build folder already exists.

-J${workspaceFolder}/build/mod makes it even cleaner, but one definitely has to manually create that folder.