This somewhat works around some changes to cape, which I was abusing to
effectively get a capf yasnippet function that would only return results
on exact matches. This allows normal lsp completion to work just fine,
except for exact matches against specific snippets.
Now we use the yasnippet-capf package instead, no longer needing the
company-yasnippet package, and hacking it to also only give a single
result back, with some caveats.
When lsp-mode is active, it tries to ensure it's own
lsp-completion-at-point function is listed before any other functions in
completion-at-point-functions.
This however prevents completions for yasnippet snippets and
files/folders from working, as completion never moved on beyond
lsp-completion-at-point. Previously I had managed to fix this by using
the DEPTH option of add-hook to get siren-yasnippet-capf and cape-file
to run before lsp-completion-at-point.
But it seems lsp-mode has changed from using add-hook to a more custom
method of always ensuring lsp-completion-at-point is always first on the
list. Hence we need to the same using the new siren-prepend macro I
recently added.
I opted for accepting copilot completions using C-<tab> /
<backtab> (shift+tab) instead of regular tab, as it was often getting in
the way of yasnippet and lsp completion suggestions. This allows a more
explicit acceptance of Copilot suggestions.
This applies especially in lsp-mode. Yasnippet snippets now show as
completion candidates if the word at point exactly matches a snippet
keyword, otherwise it'll fallback to normal lsp backed completion.
And it also supports completing file/directory names now too while
lsp-mode is active.
All this is done by modifying completion-at-point-functions after
lsp-mode has done it's trickery with it. Along with a dirty hack to
company-yasnippet to make it only activate on exact matches. Without
this hack, lsp backed completion rarely activates as snippets would have
higher priority if there's any partial matches.
