[why]
The D2Coding font has a lot of glyphs shared between multiple unicode codepoints.
Usually we just want to change the glyph on one particular codepoint and not on all linked ones; which will affect codepoints not in our patching ranges.
For example the glyph FULL BLOCK is used by codepoint 2588 and E286. In the Exxx range they have a lot of icons, and also a full block.
[how]
Remove all links on glyphs that we are about to patch over, so that we really just patch the codepoint we want to patch (and have no hidden 'links').
[note]
This could in principle break alts or ligs if they rely on another codepoint that we removed. But breaking ligs is always a possibility when patching over existing glyphs.
[note]
I checked several (not all) fonts in our repertoire, and only D2coding is affected.
[why] The D2Coding font has a lot of glyphs shared between multiple unicode codepoints. Usually we just want to change the glyph on one particular codepoint and not on all linked ones; which will affect codepoints not in our patching ranges.
For example the glyph FULL BLOCK is used by codepoint
2588andE286. In theExxxrange they have a lot of icons, and also a full block.[how] Remove all links on glyphs that we are about to patch over, so that we really just patch the codepoint we want to patch (and have no hidden 'links').
[note] This could in principle break alts or ligs if they rely on another codepoint that we removed. But breaking ligs is always a possibility when patching over existing glyphs.
[note] I checked several (not all) fonts in our repertoire, and only D2coding is affected.
Fixes: #1454
Reported-by: @hdd1013
Requirements / Checklist
What does this Pull Request (PR) do?
How should this be manually tested?
Once check one font file of all source-fonts via ... there is a test script for that?
Any background context you can provide?
What are the relevant tickets (if any)?
Screenshots (if appropriate or helpful)