python · pablogsal · Mar 18, 2021 · Mar 3, 2021 · Mar 17, 2021
diff --git a/Grammar/python.gram b/Grammar/python.gram
@@ -211,13 +211,15 @@ finally_block[asdl_stmt_seq*]: 'finally' ':' a=block { a }
 match_stmt[stmt_ty]:
    | "match" subject=subject_expr ':' NEWLINE INDENT cases[asdl_match_case_seq*]=case_block+ DEDENT {
        CHECK_VERSION(stmt_ty, 10, "Pattern matching is", _Py_Match(subject, cases, EXTRA)) }
+    | invalid_match_stmt
 subject_expr[expr_ty]:
    | value=star_named_expression ',' values=star_named_expressions? {
        _Py_Tuple(CHECK(asdl_expr_seq*, _PyPegen_seq_insert_in_front(p, value, values)), Load, EXTRA) }
    | named_expression
 case_block[match_case_ty]:
    | "case" pattern=patterns guard=guard? ':' body=block {
        _Py_match_case(pattern, guard, body, p->arena) }
+    | invalid_case_block
 guard[expr_ty]: 'if' guard=named_expression { guard }

 patterns[expr_ty]:
@@ -853,3 +855,9 @@ invalid_except_block:
        RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "exception group must be parenthesized") }
    | 'except' expression ['as' NAME ] &&':'
    | 'except' &&':' 
+
+invalid_match_stmt:
+    | "match" subject_expr !':' { CHECK_VERSION(void*, 10, "Pattern matching is", RAISE_SYNTAX_ERROR("expected ':'") ) }
+
+invalid_case_block:
+    | "case" patterns guard? !':' { RAISE_SYNTAX_ERROR("expected ':'") }
diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
@@ -825,6 +825,24 @@
   Traceback (most recent call last):
   SyntaxError: expected ':'

+   >>> match x
+   ...   case list():
+   ...       pass
+   Traceback (most recent call last):
+   SyntaxError: expected ':'
+
+   >>> match x:
+   ...   case list()
+   ...       pass
+   Traceback (most recent call last):
+   SyntaxError: expected ':'
+
+   >>> match x:
+   ...   case [y] if y > 0
+   ...       pass
+   Traceback (most recent call last):
+   SyntaxError: expected ':'
+
 Make sure that the old "raise X, Y[, Z]" form is gone:
   >>> raise X, Y
   Traceback (most recent call last):
@@ -1159,6 +1177,24 @@ def test_error_parenthesis(self):
        for paren in ")]}":
            self._check_error(paren + "1 + 2", f"unmatched '\\{paren}'")

+    def test_match_call_does_not_raise_syntax_error(self):
+        code = """
+def match(x):
+    return 1+1
+
+match(34)
+"""
+        compile(code, "<string>", "exec")
+
+    def test_case_call_does_not_raise_syntax_error(self):
+        code = """
+def case(x):
+    return 1+1
+
+case(34)
+"""
+        compile(code, "<string>", "exec")
+

 def test_main():
    support.run_unittest(SyntaxTestCase)