Fix #20958: Support .git/info/exclude for --exclude-gitignore (#21286)

RogerJinIS · newmoooon · web-flow · commit 3bf45e6c7938 · 2026-04-22T17:19:47.000+01:00
### Summary Fixes #20958. --exclude-gitignore now respects patterns in .git/info/exclude, not just .gitignore files. Previously, mypy ignored .git/info/exclude entirely, causing files matched by those patterns to still be checked. ### Changes File: mypy/modulefinder.py — find_gitignores() File: test-data/unit/cmdline.test Added handling for .git/info/exclude inside the git root detection branch. When find_gitignores identifies a directory as a git root (i.e. it contains a .git folder), it now also checks for .git/info/exclude. If the file exists, it is parsed with PathSpec.from_lines("gitignore", ...) and included in the returned list of gitignore specs, alongside any .gitignore found in the same directory. Parse errors are printed to stderr and the file is skipped, matching the existing behavior for malformed .gitignore files. --------- Co-authored-by: Cindy Wang <xinyuew4@andrew.cmu.edu>
diff --git a/mypy/modulefinder.py b/mypy/modulefinder.py
@@ -728,6 +728,14 @@ def find_gitignores(dir: str) -> list[tuple[str, PathSpec]]:
     parent_dir = os.path.dirname(dir)
     if parent_dir == dir or os.path.exists(os.path.join(dir, ".git")):
         parent_gitignores = []
+        git_info_exclude = os.path.join(dir, ".git", "info", "exclude")
+        if os.path.isfile(git_info_exclude):
+            with open(git_info_exclude) as f:
+                exclude_lines = f.readlines()
+            try:
+                parent_gitignores = [(dir, PathSpec.from_lines("gitignore", exclude_lines))]
+            except GitIgnorePatternError:
+                print(f"error: could not parse {git_info_exclude}", file=sys.stderr)
     else:
         parent_gitignores = find_gitignores(parent_dir)
 
diff --git a/test-data/unit/cmdline.test b/test-data/unit/cmdline.test
@@ -989,6 +989,17 @@ b
 [out]
 b/bpkg.py:1: error: "int" not callable
 
+[case testCmdlineExcludeGitignoreWithGitInfoExclude]
+# cmd: mypy --exclude-gitignore .
+[file .git/info/exclude]
+abc
+[file abc/apkg.py]
+1()
+[file c/cpkg.py]
+1()
+[out]
+c/cpkg.py:1: error: "int" not callable
+
 [case testCmdlineCfgExclude]
 # cmd: mypy .
 [file mypy.ini]
