Use --query_file to avoid to long args (#272)

`bazel_query` passed the query expression as a single `argv` element. PR
with a huge diff caused `OSError: [Errno 7] Argument list too long`.
Instead use `--query_file` now.

Author: martin4861

tools/lint/changed_targets.py

@@ -12,6 +12,7 @@
 import os
 import subprocess
 import sys
+import tempfile
 from pathlib import Path
 from typing import Callable, Sequence
 
@@ -106,23 +107,28 @@ def query_labels(result: subprocess.CompletedProcess) -> list[str]:
 
 def bazel_query(workspace: Path) -> RunQuery:
     def run(expression: str) -> list[str]:
-        return query_labels(
-            subprocess.run(
-                [
-                    "bazel",
-                    "query",
-                    "--keep_going",
-                    "--output=label",
-                    "--noshow_progress",
-                    "--ui_event_filters=-info",
-                    expression,
-                ],
-                cwd=workspace,
-                check=False,
-                capture_output=True,
-                text=True,
+        with tempfile.NamedTemporaryFile(
+            "w", suffix=".query", encoding="utf-8"
+        ) as query_file:
+            query_file.write(expression)
+            query_file.flush()
+            return query_labels(
+                subprocess.run(
+                    [
+                        "bazel",
+                        "query",
+                        "--keep_going",
+                        "--output=label",
+                        "--noshow_progress",
+                        "--ui_event_filters=-info",
+                        f"--query_file={query_file.name}",
+                    ],
+                    cwd=workspace,
+                    check=False,
+                    capture_output=True,
+                    text=True,
+                )
             )
-        )
 
     return run
 

tools/lint/test_changed_targets.py

@@ -8,13 +8,15 @@
 import io
 import subprocess
 import unittest
+from pathlib import Path
 from unittest import mock
 
 import tools.lint.changed_targets as changed_targets
 from tools.lint.changed_targets import (
     QUERY_PARTIAL_EXIT_CODE,
     SOURCE_EXTENSIONS,
     QueryError,
+    bazel_query,
     main,
     owning_targets,
     parse_args,
@@ -148,6 +150,36 @@ def test_other_failure_raises(self):
         self.assertEqual(raised.exception.returncode, 1)
 
 
+class TestBazelQuery(unittest.TestCase):
+    def run_query(self, expression: str) -> subprocess.CompletedProcess:
+        recorded = {}
+
+        def fake_run(command, **kwargs):
+            recorded["command"] = command
+            query_file = command[-1].removeprefix("--query_file=")
+            recorded["expression"] = Path(query_file).read_text()
+            return completed(0, "//a:a\n")
+
+        with mock.patch.object(subprocess, "run", side_effect=fake_run):
+            bazel_query(Path("/workspace"))(expression)
+        return recorded
+
+    def test_expression_goes_to_a_file_not_argv(self):
+        """A large pull request exceeds MAX_ARG_STRLEN if the expression is an argument."""
+        expression = "same_pkg_direct_rdeps(set(%s))" % " ".join(
+            f"pkg/file{index}.cc" for index in range(20000)
+        )
+        recorded = self.run_query(expression)
+        self.assertEqual(recorded["expression"], expression)
+        self.assertNotIn(expression, recorded["command"])
+        self.assertTrue(recorded["command"][-1].startswith("--query_file="))
+
+    def test_query_file_is_removed(self):
+        recorded = self.run_query("//a:a")
+        query_file = recorded["command"][-1].removeprefix("--query_file=")
+        self.assertFalse(Path(query_file).exists())
+
+
 class TestMain(unittest.TestCase):
     def run_main(self, run_query):
         with (