try/catch all of visitor

Author: tybug

hypothesis-python/src/hypothesis/internal/constants_ast.py

@@ -98,17 +98,17 @@ def constants_from_module(module: ModuleType) -> AbstractSet[ConstantT]:
     try:
         source = inspect.getsource(module)
         tree = ast.parse(source)
+        visitor = ConstantVisitor()
+        visitor.visit(tree)
     except Exception:
+        # A bunch of things can go wrong here.
+        # * `module` may have a missing or wrong source location
+        # * ast.parse may fail on the source code
+        # * NodeVisitor may hit a RecursionError (see many related issues on
+        #   e.g. libcst https://github.com/Instagram/LibCST/issues?q=recursion),
+        #   or a MemoryError (`"[1, " * 200 + "]" * 200`)
         return set()
 
-    visitor = ConstantVisitor()
-    try:
-        visitor.visit(tree)
-    except RecursionError:  # pragma: no cover
-        # NodeVisitor has a recursive structure, and so deeply nested expressions
-        # can hit the recursion limit. See the many related issues on e.g. libcst:
-        # https://github.com/Instagram/LibCST/issues?q=recursion
-        pass
     return visitor.constants
 
 

hypothesis-python/tests/cover/test_constants_ast.py

@@ -9,6 +9,7 @@
 # obtain one at https://mozilla.org/MPL/2.0/.
 
 import ast
+import inspect
 import subprocess
 import sys
 import textwrap
@@ -190,3 +191,15 @@ def test_constants_from_bad_module():
 )
 def test_local_modules_ignores_test_modules(path):
     assert not _is_local_module_file(path)
+
+
+def test_ignores_ast_parse_error(tmp_path):
+    p = tmp_path / "errors_on_parse.py"
+    p.write_text("[1, " * 200 + "]" * 200)
+    module = ModuleType("<test_constants_from_module_large_string>")
+    module.__file__ = str(p)
+
+    with pytest.raises(MemoryError):
+        ast.parse(inspect.getsource(module))
+
+    assert constants_from_module(module) == set()