bugale · bugale · Aug 14, 2026 · Aug 14, 2026
diff --git a/README.md b/README.md
@@ -39,8 +39,9 @@ steps:
   repository. If set to an empty string, the action will not write a SARIF file. The SARIF is always generated and printed to the workflow log.
 
 - `comment`: Set to true to comment on the PR with the issues. If set to false or ommitted, the action will not comment on the PR. Issues that carry a fix are
-  commented as [suggested changes](#suggested-changes). An issue is commented on only if every line it spans is part of the pull request's diff, as GitHub
-  rejects comments anchored outside it.
+  commented as [suggested changes](#suggested-changes). An issue is commented on only if the pull request's diff adds at least one of the lines it spans, as
+  GitHub rejects comments anchored outside the diff. An issue whose range reaches beyond what the diff shows is anchored on the part of it that the diff does
+  show, and its fix is then rendered as plain text rather than as a suggestion, since applying it would rewrite lines the pull request does not show.
 
 - `summary`: True by default - generates a markdown summary for the job. If set to false, the action will not generate a markdown summary.
 
@@ -210,6 +211,11 @@ commented as a suggestion. To have one commented, widen the replacement to cover
 
 The fixes Bugalint writes out always use the second form, so a fix survives being read back from a SARIF file that Bugalint itself generated.
 
+A fix is offered as a suggestion only when the pull request's diff shows every line the issue spans. A formatter reformatting a whole statement because one of
+its lines changed reports a range reaching past the three context lines the diff carries around that change, and GitHub rejects a comment anchored outside the
+diff. Such an issue is still commented on, anchored on the lines of its range that the diff does show, with its fix rendered as a plain code block and a note
+naming the lines it covers, since applying it in one click would rewrite lines the pull request does not show.
+
 ### Example With Custom Regex
 
 This is an example of how this action can be used to parse the output of a hypothetical custom linter called `mylinter`, which outputs issues in the following

diff --git a/__tests__/bugalint.test.ts b/__tests__/bugalint.test.ts
@@ -7,7 +7,7 @@ import {
   getRegexParser,
   parseDiffLines,
   isNewIssue,
-  isCommentableIssue,
+  getCommentAnchor,
   failOnIssues,
   filterNewIssues,
   _testExports,
@@ -75,11 +75,26 @@ index 1111111..2222222 100644
     expect(isNewIssue({ path: 'A/B/test.py' }, diffLines, '.')).toBe(false)
   })
 
-  it('comments only on issues whose whole range is in the diff', () => {
-    expect(isCommentableIssue({ path: 'A/B/test.py', line: 1, eline: 3 }, diffLines, '.')).toBe(true)
-    expect(isCommentableIssue({ path: 'A/B/test.py', line: 3, eline: 4 }, diffLines, '.')).toBe(false)
-    expect(isCommentableIssue({ path: 'A/B/other.py', line: 1 }, diffLines, '.')).toBe(false)
-    expect(isCommentableIssue({ path: 'A/B/test.py' }, diffLines, '.')).toBe(false)
+  it('anchors a comment on the whole range when the diff shows all of it', () => {
+    const anchor = { path: 'A/B/test.py', line: 1, eline: 3, partial: false }
+    expect(getCommentAnchor({ path: 'A/B/test.py', line: 1, eline: 3 }, diffLines, '.')).toStrictEqual(anchor)
+  })
+
+  it('anchors a comment on the shown part of a range the diff cuts off', () => {
+    const anchor = { path: 'A/B/test.py', line: 3, eline: 3, partial: true }
+    expect(getCommentAnchor({ path: 'A/B/test.py', line: 3, eline: 4 }, diffLines, '.')).toStrictEqual(anchor)
+  })
+
+  it('relativizes the anchor path to the analysis path', () => {
+    const anchor = { path: 'A/B/test.py', line: 3, eline: 3, partial: false }
+    expect(getCommentAnchor({ path: 'test.py', line: 3 }, diffLines, 'A\\B')).toStrictEqual(anchor)
+  })
+
+  it('anchors nothing on an issue the diff does not add', () => {
+    expect(getCommentAnchor({ path: 'A/B/test.py', line: 1 }, diffLines, '.')).toBeUndefined()
+    expect(getCommentAnchor({ path: 'A/B/other.py', line: 1 }, diffLines, '.')).toBeUndefined()
+    expect(getCommentAnchor({ path: 'A/B/test.py' }, diffLines, '.')).toBeUndefined()
+    expect(getCommentAnchor({ line: 2 }, diffLines, '.')).toBeUndefined()
   })
 
   describe('failOnIssues', () => {
@@ -152,6 +167,46 @@ describe('commentBody', () => {
   })
 })
 
+describe('fixBeyondDiff', () => {
+  const diff = [
+    'diff --git a/A.cpp b/A.cpp',
+    'index 1111111..2222222 100644',
+    '--- a/A.cpp',
+    '+++ b/A.cpp',
+    '@@ -874,7 +874,7 @@',
+    ' &obja,',
+    ' &iosb,',
+    ' nullptr,',
+    '-    FLAG_A | FLAG_B | FLAG_C,',
+    '+    FLAG_A | FLAG_B,',
+    ' nullptr,',
+    ' 0,',
+    ' CreateFileTypeNone,',
+    ''
+  ].join('\n')
+  const diffLines = parseDiffLines(diff)
+  const issue = { level: 'warning' as const, path: 'A.cpp', line: 868, eline: 883, fix: ['status = f(a,', '          b);'] }
+  const tag = '<!-- bugale/bugalint clang-format -->'
+
+  it('anchors on the lines the hunk shows when the fix reaches past both of its ends', () => {
+    expect(getCommentAnchor(issue, diffLines, '.')).toStrictEqual({ path: 'A.cpp', line: 874, eline: 880, partial: true })
+  })
+
+  it('offers the fix as plain text rather than a suggestion, naming the lines it covers', () => {
+    expect(_testExports.buildCommentBody(tag, 'clang-format', issue, true)).toBe(
+      `${tag}\n[warning:clang-format]\n` +
+        'The pull request diff does not show all of lines 868-883, so this replacement cannot be offered as a suggestion:\n' +
+        '```\nstatus = f(a,\n          b);\n```'
+    )
+  })
+
+  it('still offers a suggestion once the diff shows the whole fix', () => {
+    expect(_testExports.buildCommentBody(tag, 'clang-format', issue)).toBe(
+      `${tag}\n[warning:clang-format]\n\`\`\`suggestion\nstatus = f(a,\n          b);\n\`\`\``
+    )
+  })
+})
+
 describe('sarifFix', () => {
   const fixOf = (region: Region, deletedRegion: Region, text: string): string[] | undefined => {
     const log = {
@@ -304,8 +359,8 @@ describe('invertedRange', () => {
 
   it('never reaches a comment anchor whose start follows its end', () => {
     const diffLines = parseDiffLines('diff --git a/t.py b/t.py\n--- a/t.py\n+++ b/t.py\n@@ -1,1 +1,3 @@\n x\n+y\n+z\n')
-    expect(isCommentableIssue({ path: 't.py', line: 2, eline: 3 }, diffLines, '.')).toBe(true)
-    expect(isCommentableIssue({ path: 't.py', line: 3, eline: 2 }, diffLines, '.')).toBe(false)
+    expect(getCommentAnchor({ path: 't.py', line: 2, eline: 3 }, diffLines, '.')).toStrictEqual({ path: 't.py', line: 2, eline: 3, partial: false })
+    expect(getCommentAnchor({ path: 't.py', line: 3, eline: 2 }, diffLines, '.')).toBeUndefined()
   })
 })
 

diff --git a/dist/index.js b/dist/index.js
@@ -29940,7 +29940,7 @@ exports.addComments = addComments;
 exports.getPrDiff = getPrDiff;
 exports.parseDiffLines = parseDiffLines;
 exports.isNewIssue = isNewIssue;
-exports.isCommentableIssue = isCommentableIssue;
+exports.getCommentAnchor = getCommentAnchor;
 exports.filterNewIssues = filterNewIssues;
 exports.failOnIssues = failOnIssues;
 exports.createSummary = createSummary;
@@ -30201,14 +30201,19 @@ function getKnownParser(identifier, message) {
 function getRegexParser(regex, message, levelMap) {
     return (input) => appendMessage(parseRegex(input, regex, levelMap), message);
 }
-function buildCommentBody(commentTag, identifier, issue) {
+function buildCommentBody(commentTag, identifier, issue, partial = false) {
     const identifiers = `[${[issue.level, identifier, issue.id, issue.sym].filter((n) => n).join(':')}]`;
     const body = `${commentTag}\n${[issue.msg != null && issue.msg !== '' ? `**${issue.msg}**` : undefined, identifiers].filter((n) => n).join('\n')}`;
     if (issue.fix == null || (issue.fix.length === 1 && issue.fix[0] === '')) {
         return body;
     }
     const fence = '`'.repeat(Math.max(3, ...Array.from(issue.fix.join('\n').matchAll(/`+/g), (m) => m[0].length + 1)));
-    return `${body}\n${fence}suggestion\n${issue.fix.map((line) => `${line}\n`).join('')}${fence}`;
+    const fix = issue.fix.map((line) => `${line}\n`).join('');
+    if (!partial) {
+        return `${body}\n${fence}suggestion\n${fix}${fence}`;
+    }
+    const note = `The pull request diff does not show all of lines ${issue.line}-${issue.eline ?? issue.line}, so this replacement cannot be offered as a suggestion:`;
+    return `${body}\n${note}\n${fence}\n${fix}${fence}`;
 }
 async function addComments(issues, prDiff, githubToken, identifier, owner, repo, prNumber, analysisPath) {
     /* eslint camelcase: ["error", {allow: ['^pull_number$', '^comment_id$', '^start_side$', '^start_line$']}] */
@@ -30227,22 +30232,22 @@ async function addComments(issues, prDiff, githubToken, identifier, owner, repo,
     const comments = [];
     for (const issue of issues) {
         (0, core_1.debug)(`Processing issue on ${issue.path}:${issue.line}`);
-        if (!isCommentableIssue(issue, diffLines, analysisPath)) {
-            (0, core_1.debug)(`Skipping issue on ${issue.path}:${issue.line} because it is not on lines the pull request diff shows`);
+        const anchor = getCommentAnchor(issue, diffLines, analysisPath);
+        if (anchor == null) {
+            (0, core_1.debug)(`Skipping issue on ${issue.path}:${issue.line} because it is not on lines the pull request adds`);
             continue;
         }
         if (comments.length >= 50) {
             (0, core_1.warning)('More than 50 comments detected. Only the first 50 will be posted.');
             break;
         }
-        const endLine = issue.eline ?? issue.line;
         const args = {
-            path: normalizePath(issue.path, analysisPath),
+            path: anchor.path,
             side: 'RIGHT',
             start_side: 'RIGHT',
-            line: endLine,
-            start_line: endLine === issue.line ? undefined : issue.line,
-            body: buildCommentBody(commentTag, identifier, issue)
+            line: anchor.eline,
+            start_line: anchor.eline === anchor.line ? undefined : anchor.line,
+            body: buildCommentBody(commentTag, identifier, issue, anchor.partial)
         };
         (0, core_1.debug)(`Generating comment ${JSON.stringify(args)}`);
         comments.push(args);
@@ -30304,12 +30309,30 @@ function isNewIssue(issue, diffLines, analysisPath) {
     const lines = diffLines[normalizePath(issue.path, analysisPath)];
     return issueLines(issue.line, issue.eline).some((line) => lines?.[line] ?? false);
 }
-function isCommentableIssue(issue, diffLines, analysisPath) {
-    if (!isNewIssue(issue, diffLines, analysisPath)) {
-        return false;
+function getCommentAnchor(issue, diffLines, analysisPath) {
+    if (issue.path == null || issue.line == null) {
+        return undefined;
     }
-    const lines = diffLines[normalizePath(issue.path, analysisPath)];
-    return issueLines(issue.line, issue.eline).every((line) => lines?.[line] != null);
+    const commentPath = normalizePath(issue.path, analysisPath);
+    const lines = diffLines[commentPath];
+    const eline = issue.eline ?? issue.line;
+    const range = issueLines(issue.line, eline);
+    const added = range.find((line) => lines?.[line] ?? false);
+    if (added == null) {
+        return undefined;
+    }
+    if (range.every((line) => lines?.[line] != null)) {
+        return { path: commentPath, line: issue.line, eline, partial: false };
+    }
+    let start = added;
+    let end = added;
+    while (start > issue.line && lines?.[start - 1] != null) {
+        start--;
+    }
+    while (end < eline && lines?.[end + 1] != null) {
+        end++;
+    }
+    return { path: commentPath, line: start, eline: end, partial: true };
 }
 function filterNewIssues(issues, prDiff, analysisPath) {
     const diffLines = parseDiffLines(prDiff);

diff --git a/src/bugalint.ts b/src/bugalint.ts
@@ -297,14 +297,19 @@ export function getRegexParser(regex: RegExp, message: string, levelMap?: Record
   return (input: string) => appendMessage(parseRegex(input, regex, levelMap), message)
 }
 
-function buildCommentBody(commentTag: string, identifier: string, issue: Issue): string {
+function buildCommentBody(commentTag: string, identifier: string, issue: Issue, partial = false): string {
   const identifiers = `[${[issue.level, identifier, issue.id, issue.sym].filter((n) => n).join(':')}]`
   const body = `${commentTag}\n${[issue.msg != null && issue.msg !== '' ? `**${issue.msg}**` : undefined, identifiers].filter((n) => n).join('\n')}`
   if (issue.fix == null || (issue.fix.length === 1 && issue.fix[0] === '')) {
     return body
   }
   const fence = '`'.repeat(Math.max(3, ...Array.from(issue.fix.join('\n').matchAll(/`+/g), (m) => m[0].length + 1)))
-  return `${body}\n${fence}suggestion\n${issue.fix.map((line) => `${line}\n`).join('')}${fence}`
+  const fix = issue.fix.map((line) => `${line}\n`).join('')
+  if (!partial) {
+    return `${body}\n${fence}suggestion\n${fix}${fence}`
+  }
+  const note = `The pull request diff does not show all of lines ${issue.line}-${issue.eline ?? issue.line}, so this replacement cannot be offered as a suggestion:`
+  return `${body}\n${note}\n${fence}\n${fix}${fence}`
 }
 
 export async function addComments(
@@ -336,23 +341,23 @@ export async function addComments(
   const comments = []
   for (const issue of issues) {
     debug(`Processing issue on ${issue.path}:${issue.line}`)
-    if (!isCommentableIssue(issue, diffLines, analysisPath)) {
-      debug(`Skipping issue on ${issue.path}:${issue.line} because it is not on lines the pull request diff shows`)
+    const anchor = getCommentAnchor(issue, diffLines, analysisPath)
+    if (anchor == null) {
+      debug(`Skipping issue on ${issue.path}:${issue.line} because it is not on lines the pull request adds`)
       continue
     }
     if (comments.length >= 50) {
       warning('More than 50 comments detected. Only the first 50 will be posted.')
       break
     }
 
-    const endLine = issue.eline ?? issue.line
     const args = {
-      path: normalizePath(issue.path, analysisPath),
+      path: anchor.path,
       side: 'RIGHT',
       start_side: 'RIGHT',
-      line: endLine,
-      start_line: endLine === issue.line ? undefined : issue.line,
-      body: buildCommentBody(commentTag, identifier, issue)
+      line: anchor.eline,
+      start_line: anchor.eline === anchor.line ? undefined : anchor.line,
+      body: buildCommentBody(commentTag, identifier, issue, anchor.partial)
     }
     debug(`Generating comment ${JSON.stringify(args)}`)
     comments.push(args)
@@ -421,12 +426,37 @@ export function isNewIssue(issue: Issue, diffLines: DiffLines, analysisPath: str
   return issueLines(issue.line, issue.eline).some((line) => lines?.[line] ?? false)
 }
 
-export function isCommentableIssue(issue: Issue, diffLines: DiffLines, analysisPath: string): issue is Issue & Required<Pick<Issue, 'path' | 'line'>> {
-  if (!isNewIssue(issue, diffLines, analysisPath)) {
-    return false
+export interface CommentAnchor {
+  path: string
+  line: number
+  eline: number
+  partial: boolean
+}
+
+export function getCommentAnchor(issue: Issue, diffLines: DiffLines, analysisPath: string): CommentAnchor | undefined {
+  if (issue.path == null || issue.line == null) {
+    return undefined
   }
-  const lines: Record<number, boolean> | undefined = diffLines[normalizePath(issue.path, analysisPath)]
-  return issueLines(issue.line, issue.eline).every((line) => lines?.[line] != null)
+  const commentPath = normalizePath(issue.path, analysisPath)
+  const lines: Record<number, boolean> | undefined = diffLines[commentPath]
+  const eline = issue.eline ?? issue.line
+  const range = issueLines(issue.line, eline)
+  const added = range.find((line) => lines?.[line] ?? false)
+  if (added == null) {
+    return undefined
+  }
+  if (range.every((line) => lines?.[line] != null)) {
+    return { path: commentPath, line: issue.line, eline, partial: false }
+  }
+  let start = added
+  let end = added
+  while (start > issue.line && lines?.[start - 1] != null) {
+    start--
+  }
+  while (end < eline && lines?.[end + 1] != null) {
+    end++
+  }
+  return { path: commentPath, line: start, eline: end, partial: true }
 }
 
 export function filterNewIssues(issues: Iterable<Issue>, prDiff: string, analysisPath: string): Issue[] {