[Bug c++/85944] Address of temporary bound to a function parameter at global scope not considered constexpr

[Bug c++/85944] Address of temporary bound to a function parameter at global scope not considered constexpr

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85944

Patrick Palka <ppalka at gcc dot gnu.org> changed:

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

--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
The problem seems to be that maybe_nonzero_address doesn't return true for all
temporaries, only those created at function scope, but here the temporary for
'S{}' is created at namespace scope.

[Bug c++/85944] Address of temporary bound to a function parameter at global scope not considered constexpr

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85944

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fiesh at zefix dot tv

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
*** Bug 106212 has been marked as a duplicate of this bug. ***

[Bug c++/85944] Address of temporary bound to a function parameter at global scope not considered constexpr

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85944

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2021-12-06 00:00:00         |2022-7-6

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
This affects the Debug Mode checks in std::array's operator== as reported in PR
106212:

namespace std
{
  struct array
  {
    constexpr const void* data() const { return this; }

    constexpr bool operator==(const array&) const
    {
      if (data() == nullptr)
        throw 1;
      return true;
    }
  };
}

struct P {
  bool operator==(P const &) const = default;
  std::array e;
};

void f() {
  static_assert(P() == P());
}

  static_assert(P() == P());



namespace std
{
  struct array
  {
    constexpr const void* data() const { return this; }

    constexpr bool operator==(const array&) const
    {
      if (data() == nullptr)
        throw 1;
      return true;
    }
  };
}

struct P {
  bool operator==(P const &) const = default;
  std::array e;
};

void f() {
  static_assert(P() == P()); // OK
}

  static_assert(P() == P()); // NOT OK

[Bug c++/85944] Address of temporary bound to a function parameter at global scope not considered constexpr

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85944

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |johelegp at gmail dot com

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
*** Bug 107378 has been marked as a duplicate of this bug. ***

[Bug c++/85944] Address of temporary bound to a function parameter at global scope not considered constexpr

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85944

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I'm afraid the middle-end can't do here much.
maybe_nonzero_address handles file scope vars (vars in symbol table) and
automatic vars, but for the TARGET_EXPR temporaries created by
force_target_expr -> build_local_temp if they are built outside of the function
it doesn't know anything about them until they are gimplified.  They are
artificial VAR_DECLs with NULL DECL_CONTEXT, their DECL_CONTEXT will be set
only
during gimplification when the static ctors function is created.

So, either we'd need to mark such local temporaries some way that
maybe_nonzero_address could assume that while they don't look like automatic
vars yet, they will be ones later on (special attribute, or flag, etc.), or
constexpr.cc would need to handle folding those cases itself.

[Bug c++/85944] Address of temporary bound to a function parameter at global scope not considered constexpr

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85944

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |danakj at orodu dot net

--- Comment #8 from Patrick Palka <ppalka at gcc dot gnu.org> ---
*** Bug 108897 has been marked as a duplicate of this bug. ***

[Bug c++/85944] Address of temporary bound to a function parameter at global scope not considered constexpr

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85944

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |terra at gnome dot org

--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
*** Bug 109517 has been marked as a duplicate of this bug. ***

[Bug c++/85944] Address of temporary bound to a function parameter at global scope not considered constexpr

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85944

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ed at catmur dot uk

--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 109975 has been marked as a duplicate of this bug. ***

[Bug c++/85944] Address of temporary at global scope not considered constexpr

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85944

--- Comment #11 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 109976 has been marked as a duplicate of this bug. ***

[Bug c++/85944] Address of temporary at global scope not considered constexpr

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85944

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gccbugbjorn at fahller dot se

--- Comment #12 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 110828 has been marked as a duplicate of this bug. ***