bpo-44180: Report generic syntax errors in the furthest position reached in the first parser pass (GH-26253)

1 files changed, 6 insertions, 1 deletions

diff --git a/Parser/pegen.c b/Parser/pegen.c
index c2f2540..406c4e8 100644
--- a/Parser/pegen.c
+++ b/Parser/pegen.c
@@ -1281,6 +1281,7 @@ _PyPegen_run_parser(Parser *p)
 {
     void *res = _PyPegen_parse(p);
     if (res == NULL) {
+        Token *last_token = p->tokens[p->fill - 1];
         reset_parser_state(p);
         _PyPegen_parse(p);
         if (PyErr_Occurred()) {
@@ -1307,7 +1308,11 @@ _PyPegen_run_parser(Parser *p)
                 RAISE_INDENTATION_ERROR("unexpected unindent");
             }
             else {
-                RAISE_SYNTAX_ERROR("invalid syntax");
+                // Use the last token we found on the first pass to avoid reporting
+                // incorrect locations for generic syntax errors just because we reached
+                // further away when trying to find specific syntax errors in the second
+                // pass.
+                RAISE_SYNTAX_ERROR_KNOWN_LOCATION(last_token, "invalid syntax");
                 // _PyPegen_check_tokenizer_errors will override the existing
                 // generic SyntaxError we just raised if errors are found.
                 _PyPegen_check_tokenizer_errors(p);