[Bug c++/87713] New: single character underlined in an error message instead of the whole token

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87713

            Bug ID: 87713
           Summary: single character underlined in an error message
                    instead of the whole token
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

Every now and then I notice a diagnostic where only a single character of a
token (identifier?) is underlined but up until now I haven't had luck
reproducing it (often times it involves macros).  The ill-formed C++ test case
below shows one situation when this happens without macros.  Note the
underlining in the second error.

$ cat t.C && gcc -S  -Wall t.C
int i = sizeof ((int));
t.C:1:18: error: expected primary-expression before ‘int’
    1 | int i = sizeof ((int));
      |                  ^~~
t.C:1:18: error: expected ‘)’ before ‘int’
    1 | int i = sizeof ((int));
      |                 ~^~~
      |                  )
t.C:1:23: error: expected ‘)’ before ‘;’ token
    1 | int i = sizeof ((int));
      |                ~      ^
      |                       )

Other C++ compilers as well as GCC's C front end handle this more gracefully. 
They print just a single message along the lines of:

t.C:1:22: error: expected expression before ‘)’ token