[Bug c++/111122] New: local temps from get_nsdmi -> break_out_target_exprs break constexpr evaluation

[Bug c++/111122] New: local temps from get_nsdmi -> break_out_target_exprs break constexpr evaluation

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111122

            Bug ID: 111122
           Summary: local temps from get_nsdmi -> break_out_target_exprs
                    break constexpr evaluation
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

struct T {
  const char *d = new char[2] { 'o', 'k' };
  constexpr int size () const { return 2; }
  constexpr const char *data () const { return d; }
  constexpr ~T () { delete[] d; }
};
constexpr int a = T{}.size ();
constexpr int b = T{}.data ()[0];
//constexpr const char *c = T{}.data ();

is rejected by g++ with
test42.C:7:29: error: the value of ‘<anonymous>’ is not usable in a constant
expression
    7 | constexpr int a = T{}.size ();
      |                             ^
test42.C:7:21: note: ‘<anonymous>’ was not declared ‘constexpr’
    7 | constexpr int a = T{}.size ();
      |                     ^
test42.C:8:32: error: the value of ‘<anonymous>’ is not usable in a constant
expression
    8 | constexpr int b = T{}.data ()[0];
      |                                ^
test42.C:8:21: note: ‘<anonymous>’ was not declared ‘constexpr’
    8 | constexpr int b = T{}.data ()[0];
      |                     ^
during potential_constant_expression_1,
while clang++ accepts it.

[Bug c++/111122] local temps from get_nsdmi -> break_out_target_exprs break constexpr evaluation

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111122

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Try from inside a function instead. There is another bug about local Temps used
from constexpr from a non-function scope causinbissues.

[Bug c++/111122] local temps from get_nsdmi -> break_out_target_exprs break constexpr evaluation

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111122

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Sure,

struct T {
  const char *d = init ();
  constexpr int size () const { return 2; }
  constexpr const char *data () const { return d; }
  constexpr const char *init () const { return new char[2] { 'o', 'k' }; }
  constexpr ~T () { delete[] d; }
};
constexpr int a = T{}.size ();
constexpr int b = T{}.data ()[0];

works.