[Bug c++/126599] [reflection] display_string_of(nullptr-pointer-to-data-member) is "-1"

[jakub at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126599

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
For
struct S { int s, t; };
template <auto M>
void foo (int);
void
bar ()
{
  foo <(int S::*)nullptr> ();
  foo <&S::s> ();
  foo <&S::t> ();
}
we diagnose
pr126599.C: In function ‘void bar()’:
pr126599.C:7:27: error: no matching function for call to ‘foo<-1>()’
    7 |   foo <(int S::*)nullptr> ();
      |   ~~~~~~~~~~~~~~~~~~~~~~~~^~
  • there is 1 candidate
    • candidate 1: ‘template<auto M> void foo(int)’
      pr126599.C:3:6:
          3 | void foo (int);
            |      ^~~
      • candidate expects 1 argument, 0 provided
pr126599.C:8:15: error: no matching function for call to ‘foo<&S::s>()’
    8 |   foo <&S::s> ();
      |   ~~~~~~~~~~~~^~
  • there is 1 candidate
    • candidate 1: ‘template<auto M> void foo(int)’
      pr126599.C:3:6:
          3 | void foo (int);
            |      ^~~
      • candidate expects 1 argument, 0 provided
pr126599.C:9:15: error: no matching function for call to ‘foo<&S::t>()’
    9 |   foo <&S::t> ();
      |   ~~~~~~~~~~~~^~
  • there is 1 candidate
    • candidate 1: ‘template<auto M> void foo(int)’
      pr126599.C:3:6:
          3 | void foo (int);
            |      ^~~
      • candidate expects 1 argument, 0 provided
&S::s and &S::t is printed for PTRMEM_CST, while -1 is printed for OFFSET_TYPE
INTEGER_CST:
216           /* A NULL pointer-to-data-member is represented by -1, not by
217              zero.  */
218           tree val = (TYPE_PTRDATAMEM_P (type)
219                       ? build_int_cst_type (type, -1)
220                       : build_int_cst (type, 0));