Fix logical checks which report position out of bounds

2 files changed, 28 insertions, 2 deletions

diff --git a/src/flake8/checker.py b/src/flake8/checker.py
index 572c153..30d44b8 100644
--- a/src/flake8/checker.py
+++ b/src/flake8/checker.py
@@ -523,8 +523,9 @@ class FileChecker(object):
             self.processor.update_checker_state_for(plugin)
             results = self.run_check(plugin, logical_line=logical_line) or ()
             for offset, text in results:
-                offset = find_offset(offset, mapping)
-                line_number, column_offset = offset
+                line_number, column_offset = find_offset(offset, mapping)
+                if line_number == column_offset == 0:
+                    LOG.warning("position of error out of bounds: %s", plugin)
                 self.report(
                     error_code=None,
                     line_number=line_number,
@@ -674,4 +675,7 @@ def find_offset(offset, mapping):
         if offset <= token_offset:
             position = token[1]
             break
+    else:
+        position = (0, 0)
+        offset = token_offset = 0
     return (position[0], position[1] + offset - token_offset)
diff --git a/tests/integration/test_checker.py b/tests/integration/test_checker.py
index 096b350..eaab5c3 100644
--- a/tests/integration/test_checker.py
+++ b/tests/integration/test_checker.py
@@ -5,6 +5,7 @@ import pytest
 from flake8 import checker
 from flake8._compat import importlib_metadata
 from flake8.plugins import manager
+from flake8.processor import FileProcessor
 
 PHYSICAL_LINE = "# Physical line content"
 
@@ -159,6 +160,27 @@ def test_line_check_results(plugin_target, len_results):
     assert file_checker.results == expected
 
 
+def test_logical_line_offset_out_of_bounds():
+    """Ensure that logical line offsets that are out of bounds do not crash."""
+
+    @plugin_func
+    def _logical_line_out_of_bounds(logical_line):
+        yield 10000, 'L100 test'
+
+    file_checker = mock_file_checker_with_plugin(_logical_line_out_of_bounds)
+
+    logical_ret = (
+        '',
+        'print("xxxxxxxxxxx")',
+        [(0, (1, 0)), (5, (1, 5)), (6, (1, 6)), (19, (1, 19)), (20, (1, 20))],
+    )
+    with mock.patch.object(
+        FileProcessor, 'build_logical_line', return_value=logical_ret,
+    ):
+        file_checker.run_logical_checks()
+        assert file_checker.results == [('L100', 0, 0, 'test', None)]
+
+
 PLACEHOLDER_CODE = 'some_line = "of" * code'