[Bug c++/113274] New: Memoization in template parameters is overly aggressive; false memoization for const pointers

[Bug c++/113274] New: Memoization in template parameters is overly aggressive; false memoization for const pointers

[janschultke at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113274

            Bug ID: 113274
           Summary: Memoization in template parameters is overly
                    aggressive; false memoization for const pointers
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: janschultke at googlemail dot com
  Target Milestone: ---

## Minimal Reproducible Example (https://godbolt.org/z/Y7Kr9o546)

template <auto>
struct A {
    static constexpr bool value = false;
};

template <auto p>
  requires __is_same(decltype(p), int*)
struct A<p> {
    static constexpr bool value = false;
};

int x = 0;
//static_assert( A<&x>::value );
static_assert( A<const_cast<const int*>(&x)>::value == false );

## Explanation

Uncommenting the first static_assert causes compilation failure of the second
static_assert.
This should definitely not happen, as the following instantiations should be
distinct:

- A<(int*) &x>
- A<(const int*) &x>

GCC aggressively memoizes the first instantiation in A<&x>, which results in
the subsequent A<(const int*)&x>::value being identical, even though it should
not be.

[Bug c++/113274] Memoization in template parameters is overly aggressive; false memoization for const pointers

[janschultke at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113274

--- Comment #1 from Jan Schultke <janschultke at googlemail dot com> ---
Original problem and more discussion:
https://stackoverflow.com/q/77774976/5740428

[Bug c++/113274] Memoization in template parameters is overly aggressive; false memoization for const pointers

[janschultke at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113274

--- Comment #2 from Jan Schultke <janschultke at googlemail dot com> ---
OOPS, I've messed up the repro. It should be true in the partial
specialization.

https://godbolt.org/z/11dW3cTfc

[Bug c++/113274] Memoization in template parameters is overly aggressive; false memoization for const pointers

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113274

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |DUPLICATE
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Dup of bug 113272.

*** This bug has been marked as a duplicate of bug 113272 ***