Approach #1: check_banned_import_if_snippet_present()

build-support/bin/check_banned_imports.py

@@ -15,8 +15,9 @@ def main() -> None:
   )
   rust_files = find_files("src/rust/engine", extension=".rs")
 
-  check_banned_import(
+  check_banned_import_if_snippet_present(
     python_files,
+    snippet_regex=r"^from __future__ import",
     bad_import_regex=r"^import subprocess$",
     correct_import_message="`from pants.util.process_handler import subprocess`"
   )
@@ -54,5 +55,19 @@ def check_banned_import(files: List[str], *, bad_import_regex: str, correct_impo
       f"{correct_import_message}. Bad files:\n{bad_files_str}")
 
 
+def check_banned_import_if_snippet_present(
+  files: List[str], *, snippet_regex: str, bad_import_regex: str, correct_import_message: str
+) -> None:
+  regex = re.compile(snippet_regex)
+  filtered_files: List[str] = []
+  for fp in files:
+    with open(fp, 'r') as f:
+      if any(re.search(regex, line) for line in f.readlines()):
+        filtered_files.append(fp)
+  check_banned_import(
+    filtered_files, bad_import_regex=bad_import_regex, correct_import_message=correct_import_message
+  )
+
+
 if __name__ == "__main__":
   main()