github: update lint.yml to post details on formatting issue

.github/workflows/lint.yml

@@ -8,6 +8,7 @@ on:
 
 permissions:
   contents: read
+  pull-requests: write
 
 jobs:
   format_code:
@@ -21,6 +22,34 @@ jobs:
         clangformat: 17.0.5
 
     - name: Run clang-format
+      id: clang_format
       run: |
         find include src -name '*.h' -o -name '*.cc' |  xargs clang-format -i -style=file -fallback-style=none
-        git diff --exit-code
+        git diff | tee fmt.patch
+        if [ -s fmt.patch ]; then
+          exit 1
+        fi
+    - uses: actions/github-script@v7
+      if: failure() && steps.clang_format.outcome == 'failure'
+      with:
+        script: |
+          const fs = require('fs');
+          const patch = fs.readFileSync('fmt.patch', { encoding: 'utf8' });
+          const comment = `clang-format 17.0.5 found issues in the formatting in your code:
+          <details>
+          <summary>
+          View the diff from clang-format:
+          </summary>
+
+          \`\`\`diff
+          ${patch}
+          \`\`\`
+
+          </details>
+          `;
+          await github.rest.issues.createComment({
+            issue_number: context.issue.number,
+            owner: context.repo.owner,
+            repo: context.repo.repo,
+            body: comment
+          });