(Fortran) FORTRAN 77 style comments

[interkosmos]

Describe the issue
Two comment styles are supported, old C (FORTRAN 77) and new !. Syntax starting with C/c in column 1 are treated as comments. The ^C comment indicator should be better replaced with ^C (appended whitespace) as a workaround.

Which language seems to have the issue?
Fortran.

Are you using highlight or highlightAuto?
highlight

Sample Code to Reproduce

module test
    implicit none
    public :: foo
contains ! <-- is treated as comment because of `c` in first column
    function foo()
        integer :: foo
        foo = 1
    end function foo
end module test

Expected behavior
Syntax starting with character c should not be treated as comments.

Additional context
The comments in fortran.js are defined as:

  const COMMENT = {
    variants: [
      hljs.COMMENT('!', '$', {relevance: 0}),
      // allow Fortran 77 style comments
      hljs.COMMENT('^C', '$', {relevance: 0})
    ]
  };

Perhaps, it is sufficient to replace ^C with ^C or ^C\s.

[joshgoebel]

Longer discussion: #2310

The space variant doesn't work because evidently C==== is a style some use (or at least it was pointed out its more than valid) ... and one could imagine other variants... perhaps \b would be better... but would anyone use CCCCCCC?

This is hard because really these should likely be two separate languages, not one.

Are you perhaps someone with a deep understanding or Fortran and the various commenting styles someone uses within the scope of the actual rules?

[interkosmos]

I agree, it’s a tricky question. Perhaps, it is better to split between FORTRAN 77 and modern Fortran, and remove the C comment indicator entirely. I’ll try to work on fortran77.js language configuration file in near future.

[joshgoebel]

@interkosmos Would you want to make a PR where we extend this to C\s and see how it goes? I'm not opposed to trying it.

I’ll try to work on fortran77.js language configuration file in near future.

Would it be that different from Fortran 90? Are these really two entirely different langauges?

[interkosmos]

Would you want to make a PR where we extend this to C\s and see how it goes? I'm not opposed to trying it.

Yeah, why not.

Would it be that different from Fortran 90? Are these really two entirely different langauges?

FORTRAN 77 is written in fixed-source format, with the first six columns of a row being reserved for comments, format descriptors, line break indications, and so on. Fortran 90 changed to free-source format, without such restrictions.

[joshgoebel]

FORTRAN 77 is written in fixed-source format, with the first six columns of a row being reserved for comments, format descriptors, line break indications, and so on. Fortran 90 changed to free-source format, without such restrictions.

Sounds about like my understanding... but for highlighting purposes how are they any different other than the ambiguity with comments? It seems right now we perfectly highlight both - with this comment exception, no?

[interkosmos]

Yes, I don’t see any edge case at the moment. So, if ^C\s checks out you would rather keep a single language file?

[nathanweeks]

FWIW, in free source form (Fortran >= 90),call SOME_SUBROUTINE is also currently treated as a comment when the call statement begins in the first column.

[joshgoebel]

Pretty sure this also resolves that no?

[nathanweeks]

Yes, it seems like it should. Looking forward to seeing it merged!