[ci] Check changed headers in clang-tidy when using --changed (#12540)

Co-authored-by: Claude <noreply@anthropic.com>

script/clang-tidy

@@ -253,19 +253,31 @@ def main():
         print(f"Split {args.split_at}/{args.split_num}: checking {len(files)} files")
 
     # Print file count before adding header file
-    print(f"\nTotal files to check: {len(files)}")
+    print(f"\nTotal cpp files to check: {len(files)}")
+
+    # Add header file for checking (before early exit check)
+    if args.all_headers and args.split_at in (None, 1):
+        # When --changed is used, only include changed headers instead of all headers
+        if args.changed:
+            all_headers = [
+                os.path.relpath(p, cwd) for p in git_ls_files(["esphome/**/*.h"])
+            ]
+            changed_headers = filter_changed(all_headers)
+            if changed_headers:
+                build_all_include(changed_headers)
+                files.insert(0, temp_header_file)
+            else:
+                print("No changed headers to check")
+        else:
+            build_all_include()
+            files.insert(0, temp_header_file)
+            print(f"Added all-include header file, new total: {len(files)}")
 
     # Early exit if no files to check
     if not files:
         print("No files to check - exiting early")
         return 0
 
-    # Only build header file if we have actual files to check
-    if args.all_headers and args.split_at in (None, 1):
-        build_all_include()
-        files.insert(0, temp_header_file)
-        print(f"Added all-include header file, new total: {len(files)}")
-
     # Print final file list before loading idedata
     print_file_list(files, "Final files to process:")
 

script/helpers.py

@@ -156,22 +156,25 @@ def print_error_for_file(file: str | Path, body: str | None) -> None:
         print()
 
 
-def build_all_include() -> None:
-    # Build a cpp file that includes all header files in this repo.
-    # Otherwise header-only integrations would not be tested by clang-tidy
+def build_all_include(header_files: list[str] | None = None) -> None:
+    # Build a cpp file that includes header files for clang-tidy to check.
+    # If header_files is provided, only include those headers.
+    # Otherwise, include all header files in the esphome directory.
 
-    # Use git ls-files to find all .h files in the esphome directory
-    # This is much faster than walking the filesystem
-    cmd = ["git", "ls-files", "esphome/**/*.h"]
-    proc = subprocess.run(cmd, capture_output=True, text=True, check=True)
+    if header_files is None:
+        # Use git ls-files to find all .h files in the esphome directory
+        # This is much faster than walking the filesystem
+        cmd = ["git", "ls-files", "esphome/**/*.h"]
+        proc = subprocess.run(cmd, capture_output=True, text=True, check=True)
 
-    # Process git output - git already returns paths relative to repo root
-    headers = [
-        f'#include "{include_p}"'
-        for line in proc.stdout.strip().split("\n")
-        if (include_p := line.replace(os.path.sep, "/"))
-    ]
+        # Process git output - git already returns paths relative to repo root
+        header_files = [
+            line.replace(os.path.sep, "/")
+            for line in proc.stdout.strip().split("\n")
+            if line
+        ]
 
+    headers = [f'#include "{h}"' for h in header_files]
     headers.sort()
     headers.append("")
     content = "\n".join(headers)