This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115d. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2024-10-26
[Moved to DR at the February, 2014 meeting.]
According to phase 2 of 5.2 [lex.phases] paragraph 1,
Each instance of a backslash character (\) immediately followed by a new-line character is deleted, splicing physical source lines to form logical source lines. Only the last backslash on any physical source line shall be eligible for being part of such a splice. If, as a result, a character sequence that matches the syntax of a universal-character-name is produced, the behavior is undefined.
There does not appear to be a good reason for the behavior to be undefined when the line splice occurs within a raw string literal, since the splicing will be reverted (5.4 [lex.pptoken] paragraph 3).
Proposed resolution (September, 2013):
Change 5.2 [lex.phases] paragraph 1 phase 2 as follows:
Each instance of a backslash character (\) immediately followed
by a new-line character is deleted, splicing physical source lines to form
logical source lines. Only the last backslash on any physical source line
shall be eligible for being part of such a splice. If, as a
result, Except for splices reverted in a raw string literal, if
a splice results in a character sequence that matches the syntax of a
universal-character-name is produced, the behavior is
undefined. A source file that is not empty and that does not end in a
new-line character, or that ends in a new-line character immediately
preceded by a backslash character before any such splicing takes place,
shall be processed as if an additional new-line character were appended to
the file.