[Bug c/52952] Wformat location info is bad (wrong column number)

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52952

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-05-22 08:29:08 UTC ---
The format string could be even something like
   void f() {
         __builtin_printf(
            u8R"abcd(%.)abcd"
               "*d");
                  }
So, the question is, if we have a way to find from the source_location on the
ADDR_EXPR around STRING_CST the original non-concatenated tokens, and given
index into the (possibly) translated STRING_CST redo the lexing of those
tokens, looking at which byte in the source tokens maps to that offset in the
STRING_CST.