gh-102856: Allow comments inside multi-line f-string expresions

Author: cmaureir

Lib/test/test_fstring.py

@@ -644,10 +644,11 @@ def test_comments(self):
         self.assertEqual(f'{"#"}', '#')
         self.assertEqual(f'{d["#"]}', 'hash')
 
-        self.assertAllRaise(SyntaxError, "f-string expression part cannot include '#'",
-                            ["f'{1#}'",   # error because the expression becomes "(1#)"
-                             "f'{3(#)}'",
+        self.assertAllRaise(SyntaxError, "'{' was never closed",
+                            ["f'{1#}'",   # error because everything after '#' is a comment
                              "f'{#}'",
+                             "f'one: {1#}'",
+                             "f'{1# one} {2 this is a comment still#}'",
                              ])
         self.assertAllRaise(SyntaxError, r"f-string: unmatched '\)'",
                             ["f'{)#}'",   # When wrapped in parens, this becomes

Parser/tokenizer.c

@@ -1793,12 +1793,6 @@ tok_get_normal_mode(struct tok_state *tok, tokenizer_mode* current_tok, struct t
     /* Skip comment, unless it's a type comment */
     if (c == '#') {
 
-        // We don't allow # inside a one-line f-string expr,
-        // but we do in multi-line f-string expr
-        if (INSIDE_FSTRING(tok) && (tok->lineno == 1)) {
-            return MAKE_TOKEN(syntaxerror(tok, "f-string expression part cannot include '#'"));
-        }
-
         const char *prefix, *p, *type_start;
         int current_starting_col_offset;