fixed #13895/13896/13897 - improved extension handling in platform lookup

[firewave]

• only append extension to platform if missing and fixed a case it was missing
• do not look for extension-less platform files

[firewave]

@ludviggunne maybe also review since you worked on something related. Thanks.

[danmar]

I don't have a strong opinion we could allow extension-less platform files as far as I see.

[firewave]

I don't have a strong opinion we could allow extension-less platform files as far as I see.

See https://trac.cppcheck.net/ticket/12753 for some reasoning.

Do we have documentation of the lookup logic somewhere?

[ludviggunne]

@ludviggunne maybe also review since you worked on something related. Thanks.

LGTM, I think it makes sense to always use an extension for anything that's not plain text.

[ludviggunne]

Do we have documentation of the lookup logic somewhere?

I think this is the only info on custom platform files: https://github.com/danmar/cppcheck/blob/main/man/manual.md#platform

[firewave]

Do we have documentation of the lookup logic somewhere?

I think this is the only info on custom platform files: https://github.com/danmar/cppcheck/blob/main/man/manual.md#platform

Thanks. Will file a ticket and add/update it when the code is mostly aligned.