[Bug c/68473] [6 Regression] ICE: in contains_point, at diagnostic-show-locus.c:340 after error

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68473

--- Comment #2 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
It's attempting to print this source range:
(gdb) p *range
$8 = {m_start = {m_line = 13, m_column = 12},
      m_finish = {m_line = 6, m_column = 26},
      m_show_caret_p = true,
      m_caret = {m_line = 13, m_column = 12}}

i.e. (after dealing with tabs):

        0000000001111111111222222222233333333334444444444555555555566666666667
        1234567890123456879012345687901234568790123456879012345687901234568790
     1  /* { dg-options "-fdiagnostics-show-caret -mno-fp-ret-in-387" } */
     2
     3  #include <math.h>
     4
     5  #define TEST_EQ(FUNC) do { \
     6  if ((long)FUNC##l(xl,xl) != (long)xl) \
                                 ^FINISH
     7      return; \
     8    } while (0)
     9
    10  void
    11  foo (long double xl)
    12  {
    13    TEST_EQ (fmin);
                  ^
                  START&CARET
    14  }