Issue #18518: timeit now rejects statements which can't be compiled outside

a function or a loop (e.g. "return" or "break").

2 files changed, 18 insertions, 0 deletions

diff --git a/Lib/test/test_timeit.py b/Lib/test/test_timeit.py
index b3a96bb..267d2c8 100644
--- a/Lib/test/test_timeit.py
+++ b/Lib/test/test_timeit.py
@@ -73,9 +73,21 @@ class TestTimeit(unittest.TestCase):
 
     def test_timer_invalid_stmt(self):
         self.assertRaises(ValueError, timeit.Timer, stmt=None)
+        self.assertRaises(SyntaxError, timeit.Timer, stmt='return')
+        self.assertRaises(SyntaxError, timeit.Timer, stmt='yield')
+        self.assertRaises(SyntaxError, timeit.Timer, stmt='yield from ()')
+        self.assertRaises(SyntaxError, timeit.Timer, stmt='break')
+        self.assertRaises(SyntaxError, timeit.Timer, stmt='continue')
+        self.assertRaises(SyntaxError, timeit.Timer, stmt='from timeit import *')
 
     def test_timer_invalid_setup(self):
         self.assertRaises(ValueError, timeit.Timer, setup=None)
+        self.assertRaises(SyntaxError, timeit.Timer, setup='return')
+        self.assertRaises(SyntaxError, timeit.Timer, setup='yield')
+        self.assertRaises(SyntaxError, timeit.Timer, setup='yield from ()')
+        self.assertRaises(SyntaxError, timeit.Timer, setup='break')
+        self.assertRaises(SyntaxError, timeit.Timer, setup='continue')
+        self.assertRaises(SyntaxError, timeit.Timer, setup='from timeit import *')
 
     fake_setup = "import timeit; timeit._fake_timer.setup()"
     fake_stmt = "import timeit; timeit._fake_timer.inc()"
diff --git a/Lib/timeit.py b/Lib/timeit.py
index 5971d37..3807794 100755
--- a/Lib/timeit.py
+++ b/Lib/timeit.py
@@ -115,6 +115,12 @@ class Timer:
         local_ns = {}
         global_ns = _globals() if globals is None else globals
         if isinstance(stmt, str):
+            # Check that the code can be compiled outside a function
+            if isinstance(setup, str):
+                compile(setup, dummy_src_name, "exec")
+                compile(setup + '\n' + stmt, dummy_src_name, "exec")
+            else:
+                compile(stmt, dummy_src_name, "exec")
             stmt = reindent(stmt, 8)
             if isinstance(setup, str):
                 setup = reindent(setup, 4)