This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 112c. See for the official list.


2574. Undefined behavior when lexing unmatched quotes

Section: 5.4  [lex.pptoken]     Status: DR     Submitter: US     Date: 2019-10-23     Liaison: SG12

[ Resolved by paper P2621R2 (Undefined behavior in the lexer), adopted in June, 2023. ]

(From National Body comment US 027 on the C++20 DIS.)

Subclause 5.4 [lex.pptoken] paragraph 2 specifies:

If a U+0027 apostrophe or a U+0022 quotation mark character matches the last category, the behavior is undefined.

Undefined behavior during lexing is not acceptable. This ought to be ill-formed.

Additional notes (January, 2023):

Forwarded to SG12 with paper issue 1406, by decision of the CWG and SG12 chairs.