Issue #21669: Special case print & exec syntax errors

1 files changed, 25 insertions, 0 deletions

diff --git a/Lib/test/test_grammar.py b/Lib/test/test_grammar.py
index f012de1..70d85b1 100644
--- a/Lib/test/test_grammar.py
+++ b/Lib/test/test_grammar.py
@@ -390,6 +390,31 @@ class GrammarTests(unittest.TestCase):
         check_syntax_error(self, "x + 1 = 1")
         check_syntax_error(self, "a + 1 = b + 2")
 
+    # Check the heuristic for print & exec covers significant cases
+    # As well as placing some limits on false positives
+    def test_former_statements_refer_to_builtins(self):
+        keywords = "print", "exec"
+        # Cases where we want the custom error
+        cases = [
+            "{} foo",
+            "{} {{1:foo}}",
+            "if 1: {} foo",
+            "if 1: {} {{1:foo}}",
+            "if 1:\n    {} foo",
+            "if 1:\n    {} {{1:foo}}",
+        ]
+        for keyword in keywords:
+            custom_msg = "call to '{}'".format(keyword)
+            for case in cases:
+                source = case.format(keyword)
+                with self.subTest(source=source):
+                    with self.assertRaisesRegex(SyntaxError, custom_msg):
+                        exec(source)
+                source = source.replace("foo", "(foo.)")
+                with self.subTest(source=source):
+                    with self.assertRaisesRegex(SyntaxError, "invalid syntax"):
+                        exec(source)
+
     def test_del_stmt(self):
         # 'del' exprlist
         abc = [1,2,3]