port lint should warn when modeline is missing

[ryandesign (Ryan Carsten Schmidt)]

port lint should warn if the Portfile doesn't have a modeline. We recommend a ​standard modeline, but some ports use a slightly different modeline, or make it span multiple lines, or put it at the end of the Portfile. While I would prefer port authors use the standard modeline at the top of the Portfile on a single line, for lint purposes we could probably allow any modeline anywhere. Or maybe that's too hard to code, in which case we could be more restrictive.

[kurthindenburg (Kurt Hindenburg)]

My attempt - ​https://github.com/macports/macports-base/pull/26

[jmroot (Joshua Root)]

r-

The patch in the PR warns in every case except where exactly the recommended modeline is on the first line. The request here is to warn only if the Portfile doesn't have a modeline. The existing variation in modelines is valid because indentation style is up to the maintainer, and because some maintainers use a custom Portfile syntax highlighting mode in their editor and set the file type to Portfile in the modeline to enable that.

The other thing that lint should complain about is if the actual indentation doesn't match that declared in the modeline, but that might be difficult.

[kurthindenburg (Kurt Hindenburg)]

There are about 2497 warnings with the modeline on the first line; there are about 3 modelines warnings on other lines in all the Portfiles (~20k).

[ryandesign (Ryan Carsten Schmidt)]

In 24d3bd45be4359eb10fde4704e314b2df081eade/macports-base (master):

Check for tab characters in port lint

If a portfile uses a modeline that says tabs should be expanded, warn if
the portfile contains unexpanded tab characters.

See: #52767