[llvm] [Github][CI] Add `doc8` for clang-tidy documentation formatting (PR #168827)

[Baranov Victor via llvm-commits]

================
@@ -215,7 +235,125 @@ def run_clang_tidy(changed_files: List[str], args: LintArgs) -> Optional[str]:
     return clean_clang_tidy_output(proc.stdout.strip())
 
 
-def run_linter(changed_files: List[str], args: LintArgs) -> tuple[bool, Optional[dict]]:
+def clean_doc8_output(output: str) -> Optional[str]:
+    if not output:
+        return None
+
+    lines = output.split("\n")
+    cleaned_lines = []
+    in_summary = False
+
+    for line in lines:
+        if line.startswith("Scanning...") or line.startswith("Validating..."):
+            continue
+        if line.startswith("========"):
+            in_summary = True
+            continue
+        if in_summary:
+            continue
+        if line.strip():
+            cleaned_lines.append(line)
+
+    if cleaned_lines:
+        return "\n".join(cleaned_lines)
+    return None
+
+
+def get_doc8_instructions() -> str:
+    # TODO: use git diff
+    return "doc8 ./clang-tools-extra/docs/clang-tidy/checks/"
----------------
vbvictor wrote:

Should implement it in the end, it should be easy because we have `changed_files` already passed as argument - just check if one of the file there starts with "/clang-tools-extra/docs/clang-tidy/checks/".
Look at how clang-tidy handle it: `--changed-files "$CHANGED_FILES"`

https://github.com/llvm/llvm-project/pull/168827