fix(parser): support git diff.mnemonicPrefix in diff header#195
Merged
barrettruth merged 2 commits intobarrettruth:mainfrom Mar 17, 2026
Merged
fix(parser): support git diff.mnemonicPrefix in diff header#195barrettruth merged 2 commits intobarrettruth:mainfrom
barrettruth merged 2 commits intobarrettruth:mainfrom
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Looking at this later today. Did not know about this setting - thanks for ironing it out. |
letientai299
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diffs.nvim was lazy=true and only loaded as a neogit dependency, so it never activated during `git commit -v`. Also switch to fork that fixes diff.mnemonicPrefix support (upstream PR: barrettruth/diffs.nvim#195).
Problem: `git diff.mnemonicPrefix = true` produces diff headers like `diff --git c/init.lua i/init.lua` using single-letter mnemonic prefixes (`c/`, `i/`, `w/`) instead of the standard `a/`/`b/`. The parser only matched `a/.+ b/(.+)`, so mnemonic-prefixed diffs produced no highlighting. Solution: Change the pattern to `%a/.+ %a/(.+)` (Lua `%a` matches any letter), accepting any single-letter prefix while correctly rejecting numeric prefixes like `1/`/`2/`. Adds tests for both the accepted mnemonic cases and the rejected numeric case.
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When
diff.mnemonicPrefixis enabled in git config, diff headers usecontext-dependent single-letter prefixes instead of the default
a/and
b/. For example,git commit -vproduces:where
c/= commit (HEAD) andi/= index (staged). Other contextsuse
w/(worktree),o/(object), etc. The full set is documentedin git-diff(1) under
diff.mnemonicPrefix.The parser hardcoded
a/andb/, so it failed to extract thefilename from the diff header. Without a filename, filetype detection
returned nil and no syntax highlighting was applied to hunk content.
The fix replaces the literal
aandbwith%a(Lua pattern forany ASCII letter). This is a strict superset of the old behavior:
a/…b/still matches (the default prefix).c/…i/,w/…i/, etc. now also match./still won't match, so paths like1/fooor./fooare correctly rejected./.+) is unchanged, so the capture groupstill extracts the path after the second prefix.
The
diff --combinedanddiff --ccbranches are unaffected.