[Bug c/77331] New: incorrect range location in -Wformat with a concatenated format literal

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77331

            Bug ID: 77331
           Summary: incorrect range location in -Wformat with a
                    concatenated format literal
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

While getting the latest c-format.c changes integrated into the -Wformat-length
pass and testing the result I noticed that GCC underlines different parts of
the format strings than shown in the examples in the comment above the
definition of the format_warning_va function.  The output shown in the comments
makes sense.  The actual output not so much because parts of the format strings
that are unrelated to the problem are underlined.

$ cat t.c && /build/gcc-trunk/gcc/xgcc -B /build/gcc-trunk/gcc -S -Wformat
-Wformat-signedness t.c
extern int printf (const char*, ...);

void f (const char *msg)
{
  printf ("hello " "%i", msg);

#define INT_FMT "%i"

  printf ("hello " INT_FMT " world", msg);

}
t.c: In function ‘f’:
t.c:5:11: warning: format ‘%i’ expects argument of type ‘int’, but argument 2
has type ‘const char *’ [-Wformat=]
   printf ("hello " "%i", msg);
           ^~~~~~~~
t.c:5:22: note: format string is defined here
   printf ("hello " "%i", msg);
                     ~^
                     %s
t.c:9:11: warning: format ‘%i’ expects argument of type ‘int’, but argument 2
has type ‘const char *’ [-Wformat=]
   printf ("hello " INT_FMT " world", msg);
           ^~~~~~~~
t.c:7:19: note: format string is defined here
 #define INT_FMT "%i"
                  ~^
                  %s