bpo-46240: Correct the error for unclosed parentheses when the tokenizer is not finished (GH-30378)

Author: pablogsal

Lib/test/test_exceptions.py

@@ -227,7 +227,7 @@ def testSyntaxErrorOffset(self):
         check('x = "a', 1, 5)
         check('lambda x: x = 2', 1, 1)
         check('f{a + b + c}', 1, 2)
-        check('[file for str(file) in []\n])', 1, 11)
+        check('[file for str(file) in []\n]', 1, 11)
         check('a = « hello » « world »', 1, 5)
         check('[\nfile\nfor str(file)\nin\n[]\n]', 3, 5)
         check('[file for\n str(file) in []]', 2, 2)

Lib/test/test_syntax.py

@@ -1663,6 +1663,9 @@ def test_error_parenthesis(self):
         for paren in "([{":
             self._check_error(paren + "1 + 2", f"\\{paren}' was never closed")
 
+        for paren in "([{":
+            self._check_error(f"a = {paren} 1, 2, 3\nb=3", f"\\{paren}' was never closed")
+
         for paren in ")]}":
             self._check_error(paren + "1 + 2", f"unmatched '\\{paren}'")
 

Misc/NEWS.d/next/Core and Builtins/2022-01-03-23-31-25.bpo-46240.8lGjeK.rst

@@ -0,0 +1,3 @@
+Correct the error message for unclosed parentheses when the tokenizer
+doesn't reach the end of the source when the error is reported. Patch by
+Pablo Galindo

Parser/pegen_errors.c

@@ -388,7 +388,8 @@ _Pypegen_set_syntax_error(Parser* p, Token* last_token) {
     if (PyErr_Occurred()) {
         // Prioritize tokenizer errors to custom syntax errors raised
         // on the second phase only if the errors come from the parser.
-        if (p->tok->done == E_DONE && PyErr_ExceptionMatches(PyExc_SyntaxError)) {
+        int is_tok_ok = (p->tok->done == E_DONE || p->tok->done == E_OK);
+        if (is_tok_ok && PyErr_ExceptionMatches(PyExc_SyntaxError)) {
             _PyPegen_tokenize_full_source_to_check_for_errors(p);
         }
         // Propagate the existing syntax error.