Bug#1053133: Italic/slant variant is always used in Emacs, even when it shouldn't be

[Nicholas D Steeves <sten@debian.org>]

Package: fonts-courier-prime
Version: 0+git20190115-3
Severity: normal
Control: forwarded -1 https://github.com/quoteunquoteapps/CourierPrime/issues/9

Hi,

I'm currently investigating why the Italic/slant variant is always
used in Emacs, even when it shouldn't be. Thus far I've only found the
following with fontforge:

    The PostScript font name "Courier Prime-Regular" is
    invalid.
    It should be printable ASCII,
    must not contain (){}[]<>%/ or space
    and must be shorter than 63 characters
    Could that be why the slant/italics variant is matched?

I also found this:

    The glyph named Delta is mapped to U+0394.
      But its name indicates it should be mapped to U+2206.
    The glyph named Omega is mapped to U+03A9.
      But its name indicates it should be mapped to U+2126.
    The glyph named Tcommaaccent is mapped to U+021A.
      But its name indicates it should be mapped to U+0162.
    The glyph named mu is mapped to U+03BC.
      But its name indicates it should be mapped to U+00B5.
    The glyph named tcommaaccent is mapped to U+021B.
      But its name indicates it should be mapped to U+0163.

but the latter doesn't seem relevant to the italics/slant bug that I'm
reporting.

>From what I gathered on #emacs@LiberaChat, Emacs is very picky about even slightly out-of-spec fonts, but on the upside that makes it a great linter! :)

To reproduce the issue, install a GUI variant of emacs, install
fonts-courier-prime, and M-x set-frame-font to a non-italics,
non-Code, non-Sans variant of Courier Prime.

'hope someone who knows more about fonts can provide instructions/guidance to take this further.  Please CC me on all correspondences.

Regards,
Nicholas