This package uses a local USE variable of USE=vim for the same effect as the global USE=vim-syntax.
Thanks for pointing it out, assigning to maintainers.
(In reply to comment #0)
> This package uses a local USE variable of USE=vim for the same effect as the
> global USE=vim-syntax.
I don't think gtk-doc is using that USE flag for installing syntax scripts, that USE is for using vim for highlighting
It does indeed have nothing to do with vim-syntax, please see the original bug report as reported in the ChangeLog.
It seems I missed the subtle distinction between "source code highlighting through app-editors/vim" and "syntax hightlighting" in app-editors/vim.
For completeness, the bug mentioned in the ChangeLog and comment #3 is bug 306569.