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

[manu at gcc dot gnu.org]

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

--- Comment #51 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
There are few things still that don't work:

1. C++ does not work

2. Locations within strings expanded from a macro

3. Location within strings from a const char array.

void foo(void) {
#define c               " %d %d "
  __builtin_printf(c, 0.5, 0);

  const char a[] = " %d ";
  __builtin_printf(a, 0.5);
}

GCC 9:

<source>:2:25: error: format '%d' expects argument of type 'int', but argument
2 has type 'double' [-Werror=format=]
2 | #define c               " %d %d "
  |                         ^~~~~~~~~
<source>:3:20: note: in expansion of macro 'c'
3 |   __builtin_printf(c, 0.5, 0);
  |                    ^
<source>:6:20: error: format '%d' expects argument of type 'int', but argument
2 has type 'double' [-Werror=format=]
6 |   __builtin_printf(a, 0.5);
  |                    ^  ~~~
  |                       |
  |                       double

Clang can do (3) but not (2):

<source>:3:23: error: format specifies type 'int' but the argument has type
'double' [-Werror,-Wformat]
  __builtin_printf(c, 0.5, 0);
                   ~  ^~~
<source>:6:23: error: format specifies type 'int' but the argument has type
'double' [-Werror,-Wformat]
  __builtin_printf(a, 0.5);
                   ~  ^~~
<source>:5:22: note: format string is defined here
  const char a[] = " %d ";
                     ^~
                     %f