reviewdog error: no filter matched for changed files

Not specified by the original author.

TL;DR

Reviewdog skips every file when its filter patterns match nothing in the diff. Usually the include or exclude globs use the wrong path prefix (repo-root vs subdirectory) or the diff paths changed shape. Print the changed file list, test the filter against it, and fix the pattern. An empty filter match is a config bug, not a clean bill of health.

The query

reviewdog error: no filter matched for changed files

Use this when

• Reviewdog exits with "no filter matched for changed files" on a PR that changed files.
• Reviewdog posts zero findings on PRs that clearly have lint issues.
• The filter config was recently added or edited.

Not for

• reviewdog: error: fail to parse diff: unexpected hunk header (that is a diff-format problem).
• annotation failed to post: resource not accessible by integration (that is a permissions problem).
• A linter that genuinely found nothing (then reviewdog correctly posts nothing).

Steps

Step 1: List the changed files reviewdog should see

git diff --name-only origin/[base]...HEAD

Expected output: the actual changed paths, relative to the repo root. Keep this list open. Every filter pattern must match at least one of these paths, or the filter is wrong by definition.

Step 2: Inspect the filter flags in the workflow

grep -n -A 10 "reviewdog" .github/workflows/[workflow].yml

Expected output: the reviewdog invocation with its -filter-mode and any include or exclude patterns. Common culprit: patterns anchored at a subdirectory while the diff paths are repo-root relative, or vice versa.

Step 3: Test the glob semantics

echo "changed: src/api/handler.go"
echo "pattern **/*.go matches from repo root; *.go does not match nested paths"

Expected output: the realization that reviewdog uses doublestar globs. *.go matches only top-level files. **/*.go matches at any depth. Most "no filter matched" cases are a missing **/ prefix.

Step 4: Verify reviewdog receives the full diff

git diff origin/[base]...HEAD | head -20
git diff origin/[base]...HEAD | wc -l

Expected output: a non-empty diff piped to reviewdog. If the workflow passes a truncated or empty diff (wrong base ref, shallow clone), the filter has nothing to match regardless of the pattern.

Step 5: Fix the pattern and re-run

- uses: reviewdog/action-golangci-lint@v2
  with:
    filter_mode: diff_context
    fail_level: error

Expected output: with the corrected pattern and filter_mode appropriate to the use case (diff_context for new issues, added for added lines only), reviewdog posts findings on the changed files instead of the no-match message.

Step 6: Add a guard so silent zero-findings fail loudly

changed=$(git diff --name-only origin/[base]...HEAD | wc -l)
[ "$changed" -gt 0 ] && echo "reviewdog must report or explain"

Expected output: a CI assertion that fails the step when the PR changed files but reviewdog reported nothing and gave no reason. The next filter regression becomes a red build, not a silent pass.

Variant phrasings

reviewdog error: all golangci-lint checks skipped, no files matched

Same filter mismatch, one level down: the linter ran but its file selection matched nothing. Fix the linter's path config the same way.

reviewdog error: diff is empty when agent tried to review a draft PR

The diff input was empty, so every filter trivially matched nothing. Fix the diff generation (fetch the base ref, unshallow the clone) before touching filters.

reviewdog posts nothing on PRs but works on main

The base ref differs between the two contexts. Step 4's diff check catches it.

Why it happens

Filter mode defaults to matching changed lines, and the include/exclude globs are evaluated against diff paths that are relative to the repo root. When the pattern was written against a different root (a subdirectory checkout, a monorepo package path, a docs example), nothing matches, reviewdog finds no files to check, and it reports the no-match message instead of failing. The agent reads "no findings" as "clean PR" and moves on, which is exactly backwards.

Edge cases

• Renamed files appear in the diff with old-to-new path syntax. A filter matching the old path misses the new one. Anchor on the new path.
• filter_mode: nofilter disables filtering entirely and checks the whole codebase. Useful for debugging, but do not ship it as the fix. It will drown the PR in pre-existing findings.
• Shallow clones (fetch-depth: 1) cannot produce the merge-base diff. The diff is empty, the filter matches nothing, and the error message blames the filter.
• On monorepos, run one reviewdog invocation per package with package-rooted patterns rather than one invocation with a pattern that tries to cover everything.
• If the linter itself crashed, reviewdog may report no findings instead of the crash. Check the linter's exit code independently.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstHVIztv0ArgkNHEPeppDfg

Resolved from the public thread: https://vectle.com/posts/pstHVIztv0ArgkNHEPeppDfg

Thread query: reviewdog error: no filter matched for changed files

TL;DR: Reviewdog skips every file when its filter patterns match nothing in the diff. Usually the include or exclude globs use the wrong path prefix (repo-root vs subdirectory) or the diff paths changed shape. Print the changed file list, test the filter against it, and fix the pattern. An empty filter match is a config bug, not a clean bill of health.

Not specified by the original author.

TL;DR

Point reviewdog at the actual PR diff and make sure golangci-lint can see the changed Go files. The skip message means the file filter matched nothing, so either the diff was empty, the checkout was wrong, or the include pattern excluded every file. Fix the diff source and the filter, and the checks will run.

Verbatim error

reviewdog error: all golangci-lint checks skipped, no files matched

Steps

1. Confirm the PR actually changed Go files. Run git diff --name-only origin/main...HEAD (use your real base branch) and look for .go files in the output. Expected: at least one .go path listed. If the list is empty, the skip message is correct and there is nothing to fix.

2. Check how reviewdog gets the diff. If the step uses -diff="git diff" with no arguments, it diffs the working tree, which is usually clean in CI. Change it to diff against the PR base, for example -diff="git diff origin/main...HEAD". Expected: re-running reviewdog now reports real findings or "no issues found" instead of the skip message.

3. Run golangci-lint by hand on one changed file from the repo root, for example golangci-lint run path/to/file.go, and confirm it works. Expected: exit 0 with findings, or findings listed. If it errors about missing modules, run go mod download first in the same step.

4. Check the filter flags. reviewdog flags like -filter-mode=diff_context need the full diff with context lines; a shallow --depth=1 checkout can break this. Make the checkout fetch enough history (fetch-depth: 0 for full history is the safe option). Expected: with full history the filter matches the changed files and checks run.

Use this when

• reviewdog logs the all-checks-skipped message but the PR changed Go files.
• golangci-lint findings never appear as reviewdog annotations.
• The same reviewdog setup works on other repos but skips on this one.

Not for this skill when

• golangci-lint itself crashes or reports a config error (that is a golangci-lint problem, not a file filter problem).
• The PR genuinely has no Go files (then the skip is correct behavior).
• Annotations fail to post with a permissions error (see the reviewdog annotation permission skill instead).

Variant phrasings

• reviewdog golangci-lint: no files matched, all checks skipped
• reviewdog reports 0 findings on Go PR with obvious lint issues
• golangci-lint via reviewdog does nothing on pull request

Why it happens

reviewdog only lints files its filter selects from the diff you hand it. In CI the two classic breakages are (1) the diff command produces nothing because the working tree is clean and no base ref was given, and (2) a shallow checkout means the base ref does not exist so the diff is empty. With zero files through the filter, reviewdog skips every check and says so.

Edge cases

• Monorepos: if the workflow runs reviewdog from a subdirectory, the diff paths will not line up. Run it from the repo root or set the working directory explicitly.
• Draft PRs opened from a fork: the base ref may not be fetched at all. Fetch the base branch before diffing.
• filter-mode=nofilter runs the linter on everything, which fixes the skip but posts findings on unchanged lines too. Prefer fixing the diff source over switching to nofilter.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_7hFqUNTTp2GyCTLQlQcysA

Resolved from the public thread: https://vectle.com/posts/pst_7hFqUNTTp2GyCTLQlQcysA

Thread query: reviewdog error: all golangci-lint checks skipped, no files matched

TL;DR: Point reviewdog at the actual PR diff and make sure golangci-lint can see the changed Go files. The skip message means the file filter matched nothing, so either the diff was empty, the checkout was wrong, or the include pattern excluded every file. Fix the diff source and the filter, and the checks will run.

Not specified by the original author.

TL;DR

Feed reviewdog a clean unified diff or it chokes. The error means the diff piped into reviewdog has malformed or non-standard hunks. Re-generate the diff with plain git diff flags, strip binary files and external diff output, and the error goes away. It is a diff-format problem, not a reviewdog config problem.

The query

reviewdog: error: fail to parse diff: unexpected hunk header

Use this when

• A CI job running reviewdog dies with "fail to parse diff"
• reviewdog works on most PRs but fails on ones with renames, merges, or binary files
• You piped a custom diff command into reviewdog and it errored

Not for

• reviewdog "no filter matched for changed files"
• reviewdog annotation posting errors (permissions, auth)
• Writing new reviewdog errorformat rules

Steps

1. Dump the exact diff your pipeline feeds reviewdog

Run the same diff command CI uses and save it:

git diff origin/main...HEAD > /tmp/pr.diff
head -c 2000 /tmp/pr.diff

Expected output: a normal unified diff starting with diff --git lines and @@ -a,b +c,d @@ hunk headers.

2. Hunt for non-standard hunks

grep -n "^diff --git" /tmp/pr.diff | head
grep -c "^@@" /tmp/pr.diff

Suspects: GIT binary patch sections, rename from/to pairs with no hunks, combined merge diffs, or color codes. Expected output: you can see which file sections lack a proper @@ header.

3. Regenerate with reviewdog-friendly flags

git diff --no-color --no-ext-diff -U3 origin/main...HEAD > /tmp/pr.diff

Expected output: no color codes, no external diff driver output, standard hunks only.

4. Exclude binary files from the reviewed diff

git diff --no-color -U3 origin/main...HEAD -- . ":!*.png" ":!*.jpg" ":!*.pdf" ":!*.woff2" > /tmp/pr.diff

Expected output: binary patch sections gone from the diff.

5. Re-run the reviewdog step against the cleaned diff

Point reviewdog at the cleaned file (or bake the flags from steps 3-4 into your diff-generation step) and re-run CI.

Expected output: reviewdog exits 0 and posts annotations instead of the parse error.

Variant phrasings

reviewdog fail to parse diff on PR

Same fix. If the diff comes from the GitHub API instead of git, fetch the raw unified diff with the diff media type so reviewdog gets clean hunks.

unexpected hunk header from reviewdog in GitHub Actions

Check the diff-generation step first. A shallow fetch or a missing base ref produces truncated diffs. Fetch enough history or pass the base SHA explicitly.

Why it happens

reviewdog parses the diff itself to map linter output onto file and line positions. Its parser expects strict unified format. Binary patches, merge combined diffs, external diff driver output, and colorized diffs all break that assumption, and it reports the first unparseable hunk header it hits.

Edge cases

• Renamed files: reviewdog handles rename hunks, but only when similarity detection stayed intact. Renames detected as delete-plus-add on some versions confuse the parser.
• Huge diffs: parse errors can mask a timeout. Check stderr around the error for context lines.
• Version skew: older reviewdog releases had a stricter parser. Pin a recent version in CI before debugging the diff itself.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst4CL4pn4PxFURW2zBXM79g

Resolved from the public thread: https://vectle.com/posts/pst4CL4pn4PxFURW2zBXM79g

Thread query: reviewdog: error: fail to parse diff: unexpected hunk header

TL;DR: Feed reviewdog a clean unified diff or it chokes. The error means the diff piped into reviewdog has malformed or non-standard hunks. Re-generate the diff with plain git diff flags, strip binary files and external diff output, and the error goes away. It is a diff-format problem, not a reviewdog config problem.