[Bug c++/107282] New: ICE on valid code template + overloaded + visit

[Bug c++/107282] New: ICE on valid code template + overloaded + visit

[boris_oncev at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107282

            Bug ID: 107282
           Summary: ICE on valid code template + overloaded + visit
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: boris_oncev at hotmail dot com
  Target Milestone: ---

ICE on >=C++17 on all supported versions

https://godbolt.org/z/5exMcrhYz

[Bug c++/107282] ICE on valid code template + overloaded + visit

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107282

Martin Liška <marxin at gcc dot gnu.org> changed:

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

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Thanks for the report, please always paste source code here and not to an
external service:

#include <variant>

template <class... Ts>
struct overloaded : Ts... {
    using Ts::operator()...;
};

template <class... Ts>
overloaded(Ts...) -> overloaded<Ts...>;

using Var1 = std::variant<int, float>;

struct Unrelated {
    Var1 bar;
};

// works without the template
template <class T>
Var1 copyLifeState(Var1 const& value) {
    return std::visit(overloaded{
                          [](auto&) -> Var1 { return {1}; },
                          [](Unrelated& v) -> Var1 {
                              return std::visit(
                                  overloaded{
                                      [](int) -> Var1 { return {2}; },
                                      [](float) -> Var1 { return {2}; },
                                  },
                                  v.bar);
                          },
                      },
                      value);
}
int main() {
    Var1 value = 2;
    copyLifeState<int>(value);
}

[Bug c++/107282] ICE on valid code template + overloaded + visit

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107282

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2022-10-17
                 CC|                            |nathan at gcc dot gnu.org,
                   |                            |ppalka at gcc dot gnu.org

--- Comment #2 from Martin Liška <marxin at gcc dot gnu.org> ---
Reduced test-case:

$ cat pr107282.ii
template <typename _Visitor, typename _Variants>
void visit(_Visitor, _Variants);
template <class... Ts> struct overloaded : Ts... {
  using Ts::operator()...;
};
template <class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
template <class> int copyLifeState(int value) {
  visit(overloaded{[] { overloaded{[] {}}; }}, value);
  return 0;
}

int
main() { int value = copyLifeState<int>(value); }

Maybe started with r11-6855-g4804de453e7f5f90.

[Bug c++/107282] ICE on valid code template + overloaded + visit

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107282

--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Hmm, that commit seems unrelated.  Bisection for me points to
r11-2455-gc6ef9d8d3f1122 (with -g).

[Bug c++/107282] ICE on valid code template + overloaded + visit

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107282

Martin Liška <marxin at gcc dot gnu.org> changed:

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

--- Comment #4 from Martin Liška <marxin at gcc dot gnu.org> ---
Yes, sorry, I can verify it started with r11-2455-gc6ef9d8d3f11221d.

[Bug c++/107282] ICE on valid code template + overloaded + visit

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107282

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
So we are late processing (rest_of_handle_final) dwaf2out_decl of copyLifeState
and there iterating the scope vars which include a TYPE_DECL ._anon_2 here
for which we generate a type DIE because

27023         if (is_redundant_typedef (decl))
27024           gen_type_die (TREE_TYPE (decl), context_die);

but the type was already generated early and there will be no way to
refer to just the type late (or TYPE_DECLs in practice from LTO).

diff --git a/gcc/dwarf2out.cc b/gcc/dwarf2out.cc
index e81044b8c48..090465a4896 100644
--- a/gcc/dwarf2out.cc
+++ b/gcc/dwarf2out.cc
@@ -27021,7 +27021,10 @@ gen_decl_die (tree decl, tree origin, struct
vlr_context *ctx,
        break;

       if (is_redundant_typedef (decl))
-       gen_type_die (TREE_TYPE (decl), context_die);
+       {
+         if (early_dwarf)
+           gen_type_die (TREE_TYPE (decl), context_die);
+       }
       else
        /* Output a DIE to represent the typedef itself.  */
        gen_typedef_die (decl, context_die);

fixes this, but I'm not sure it isn't barking up the wrong tree given
the bisection - but that should only end up emitting more debug early
and not affect what we do late.