py/objgenerator: Check stack before resuming a generator.

This turns a hard crash in a recursive generator into a 'maximum recursion
depth exceeded' exception.

2 files changed, 10 insertions, 0 deletions

diff --git a/tests/run-tests b/tests/run-tests
index ef2f4bc6a..42037831d 100755
--- a/tests/run-tests
+++ b/tests/run-tests
@@ -367,6 +367,7 @@ def run_tests(pyb, tests, args, base_path="."):
         skip_tests.add('micropython/heapalloc_iter.py') # requires generators
         skip_tests.add('micropython/schedule.py') # native code doesn't check pending events
         skip_tests.add('stress/gc_trace.py') # requires yield
+        skip_tests.add('stress/recursive_gen.py') # requires yield
 
     for test_file in tests:
         test_file = test_file.replace('\\', '/')
diff --git a/tests/stress/recursive_gen.py b/tests/stress/recursive_gen.py
new file mode 100644
index 000000000..65f5d8d47
--- /dev/null
+++ b/tests/stress/recursive_gen.py
@@ -0,0 +1,9 @@
+# test deeply recursive generators
+
+def gen():
+    yield from gen()
+
+try:
+    list(gen())
+except RuntimeError:
+    print('RuntimeError')