[Bug c++/112288] New: internal compiler error: in instantiate_decl, at cp/pt.cc:26861

[Bug c++/112288] New: internal compiler error: in instantiate_decl, at cp/pt.cc:26861

[falemagn at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112288

            Bug ID: 112288
           Summary: internal compiler error: in instantiate_decl, at
                    cp/pt.cc:26861
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: falemagn at gmail dot com
  Target Milestone: ---

It's a regression, it compiles fine with v13.2.1.

[Bug c++/112288] internal compiler error: in instantiate_decl, at cp/pt.cc:26861

[falemagn at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112288

Fabio Alemagna <falemagn at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #56472|0                           |1
        is obsolete|                            |
                 CC|                            |falemagn at gmail dot com

--- Comment #1 from Fabio Alemagna <falemagn at gmail dot com> ---
Created attachment 56474
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56474&action=edit
Generated with -freport-bug

[Bug c++/112288] [14 Regression] ICE - internal compiler error: in instantiate_decl, at cp/pt.cc:26861

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112288

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |needs-bisection
   Target Milestone|---                         |14.0

[Bug c++/112288] [11/12/13/14 Regression] ICE - internal compiler error: in instantiate_decl, at cp/pt.cc:26861

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112288

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|needs-bisection             |ice-on-valid-code
            Summary|[14 Regression] ICE -       |[11/12/13/14 Regression]
                   |internal compiler error: in |ICE - internal compiler
                   |instantiate_decl, at        |error: in instantiate_decl,
                   |cp/pt.cc:26861              |at cp/pt.cc:26861
                 CC|                            |mpolacek at gcc dot gnu.org,
                   |                            |ppalka at gcc dot gnu.org
   Last reconfirmed|                            |2023-10-30
           Priority|P3                          |P2
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Confirmed.  Started with r6-6830-g20a0c6f9bdbd78:

commit 20a0c6f9bdbd781ed5d413a10a06764a174dc394
Author: Patrick Palka <ppalka@gcc.gnu.org>
Date:   Mon Feb 8 23:02:50 2016 +0000

    Fix PR c++/69283 (auto deduction fails when ADL is required)

but reverting that fix doesn't make the ICE go away.

[Bug c++/112288] [11/12/13/14 Regression] ICE - internal compiler error: in instantiate_decl, at cp/pt.cc:26861

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112288

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
// PR c++/112288

namespace {

template <typename Context, int Start = 0, int Step = 1>
class counter
{
public:
 template <typename Unique>
 static constexpr int next()
 {
  return next<Unique>(0)*Step+Start;
 }

private:
 template <int I>
 struct slot
 {
  template <typename Dummy>
  friend constexpr auto slot_allocated(Dummy, slot<I>);
 };

 template <int I>
 struct allocate_slot {
  template <typename Dummy>
  friend constexpr auto slot_allocated(Dummy, slot<I>) {
   return true;
  }

  enum { value = I };
 };


 template <typename Unique, int I = 0, int Dummy = 0, bool =
slot_allocated(Dummy, slot<I>())>
 static constexpr int next(int)
 {
  return next<Unique, I+1>(0);
 }


 template <typename Unique, int I = 0>
 static constexpr int next(double)
 {
  return allocate_slot<I>::value;
 }
};

}


template <int I>
struct U;

struct C: counter<U<1>>{};

int a = C::next<struct unique_1>();
int b = C::next<struct unique_2>();

[Bug c++/112288] [11/12/13/14 Regression] ICE - internal compiler error: in instantiate_decl, at cp/pt.cc:26861

[falemagn at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112288

--- Comment #4 from Fabio Alemagna <falemagn at gmail dot com> ---
(In reply to Marek Polacek from comment #2)
> Confirmed.  Started with r6-6830-g20a0c6f9bdbd78:
> 
> commit 20a0c6f9bdbd781ed5d413a10a06764a174dc394
> Author: Patrick Palka <ppalka@gcc.gnu.org>
> Date:   Mon Feb 8 23:02:50 2016 +0000
> 
>     Fix PR c++/69283 (auto deduction fails when ADL is required)
> 
> but reverting that fix doesn't make the ICE go away.

That seems waaaay to old to be the cause of the issue.

As said, it works with v13.2.1

[Bug c++/112288] [11/12/13/14 Regression] ICE - internal compiler error: in instantiate_decl, at cp/pt.cc:26861

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112288

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Fabio Alemagna from comment #4)
> (In reply to Marek Polacek from comment #2)
> > Confirmed.  Started with r6-6830-g20a0c6f9bdbd78:
> > 
> > commit 20a0c6f9bdbd781ed5d413a10a06764a174dc394
> > Author: Patrick Palka <ppalka@gcc.gnu.org>
> > Date:   Mon Feb 8 23:02:50 2016 +0000
> > 
> >     Fix PR c++/69283 (auto deduction fails when ADL is required)
> > 
> > but reverting that fix doesn't make the ICE go away.
> 
> That seems waaaay to old to be the cause of the issue.
> 
> As said, it works with v13.2.1

Note the trunk has extra checkings enabled compared to a release if not
configured with `--enable-checking=release` so you might be seeing that effect
here.

[Bug c++/112288] [11/12/13/14 Regression] ICE - internal compiler error: in instantiate_decl, at cp/pt.cc:26861

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112288

--- Comment #6 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #5)
> (In reply to Fabio Alemagna from comment #4)
> > (In reply to Marek Polacek from comment #2)
> > > Confirmed.  Started with r6-6830-g20a0c6f9bdbd78:
> > > 
> > > commit 20a0c6f9bdbd781ed5d413a10a06764a174dc394
> > > Author: Patrick Palka <ppalka@gcc.gnu.org>
> > > Date:   Mon Feb 8 23:02:50 2016 +0000
> > > 
> > >     Fix PR c++/69283 (auto deduction fails when ADL is required)
> > > 
> > > but reverting that fix doesn't make the ICE go away.
> > 
> > That seems waaaay to old to be the cause of the issue.
> > 
> > As said, it works with v13.2.1
> 
> Note the trunk has extra checkings enabled compared to a release if not
> configured with `--enable-checking=release` so you might be seeing that
> effect here.

That's right.  Trunk configured with --enable-checking=release doesn't ICE,
either.

[Bug c++/112288] [11/12/13/14 Regression] ICE - internal compiler error: in instantiate_decl, at cp/pt.cc:26861

[falemagn at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112288

--- Comment #7 from Fabio Alemagna <falemagn at gmail dot com> ---
(In reply to Marek Polacek from comment #6)
> (In reply to Andrew Pinski from comment #5)
> > (In reply to Fabio Alemagna from comment #4)
> > > (In reply to Marek Polacek from comment #2)
> > > > Confirmed.  Started with r6-6830-g20a0c6f9bdbd78:
> > > > 
> > > > commit 20a0c6f9bdbd781ed5d413a10a06764a174dc394
> > > > Author: Patrick Palka <ppalka@gcc.gnu.org>
> > > > Date:   Mon Feb 8 23:02:50 2016 +0000
> > > > 
> > > >     Fix PR c++/69283 (auto deduction fails when ADL is required)
> > > > 
> > > > but reverting that fix doesn't make the ICE go away.
> > > 
> > > That seems waaaay to old to be the cause of the issue.
> > > 
> > > As said, it works with v13.2.1
> > 
> > Note the trunk has extra checkings enabled compared to a release if not
> > configured with `--enable-checking=release` so you might be seeing that
> > effect here.
> 
> That's right.  Trunk configured with --enable-checking=release doesn't ICE,
> either.

Oh! Didn't know that, my bad.

[Bug c++/112288] [11/12/13/14 Regression] ICE - internal compiler error: in instantiate_decl, at cp/pt.cc:26861 since r6-6830-g20a0c6f9bdbd78

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112288

--- Comment #8 from Patrick Palka <ppalka at gcc dot gnu.org> ---
The issue was probably latent before r6-6830.  The testcase is kind of strange,
e.g. 'slot_allocated' is defined within 'allocate_slot' instead of within
'slot', which would arguably be more natural given that its 'slot<T>' function
parameter.  And consecutive equivalent calls to 'next' apparently resolve to
different overloads due to 'slot_allocated' being defined only after we
instantiate the second 'next' overload.

Reduced:

template<class T>
struct slot {
  template<class U>
  friend constexpr bool slot_allocated(slot<T>, U);
};

template<class T>
struct allocate_slot {
  template<class U>
  friend constexpr bool slot_allocated(slot<T>, U) { return true; }
};

template<class T, bool = slot_allocated(slot<T>{}, 0)>
constexpr int next(int) { return 0; }

template<class T>
constexpr int next(...) { allocate_slot<T> s; return 42; }

// slot_allocated<slot<int>, int>() not defined yet
static_assert(next<int>(0) == 42);
// now it's defined
static_assert(next<int>(0) == 0);

[Bug c++/112288] [11/12/13/14 Regression] ICE - internal compiler error: in instantiate_decl, at cp/pt.cc:26861 since r6-6830-g20a0c6f9bdbd78

[falemagn at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112288

--- Comment #9 from Fabio Alemagna <falemagn at gmail dot com> ---
(In reply to Patrick Palka from comment #8)
> The issue was probably latent before r6-6830.  The testcase is kind of
> strange,

It's the "friend injection" technique. In this case, it's used to create a
compile-time counter. The specific test case uses templates in such a way as to
try and circumvent a diagnostic-related bug (bug #112267), which however
triggered this other bug.

[Bug c++/112288] [11/12/13/14 Regression] ICE - internal compiler error: in instantiate_decl, at cp/pt.cc:26861 since r6-6830-g20a0c6f9bdbd78

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112288

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |ppalka at gcc dot gnu.org

--- Comment #10 from Patrick Palka <ppalka at gcc dot gnu.org> ---
(In reply to Fabio Alemagna from comment #9)
> (In reply to Patrick Palka from comment #8)
> > The issue was probably latent before r6-6830.  The testcase is kind of
> > strange,
> 
> It's the "friend injection" technique. In this case, it's used to create a
> compile-time counter. The specific test case uses templates in such a way as
> to try and circumvent a diagnostic-related bug (bug #112267), which however
> triggered this other bug.

Ah thanks, I see.  I have a fix for the failing assert.

[Bug c++/112288] [11/12/13/14/15 Regression] ICE - internal compiler error: in instantiate_decl, at cp/pt.cc:26861 since r6-6830-g20a0c6f9bdbd78

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112288

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|14.0                        |14.2

--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 14.1 is being released, retargeting bugs to GCC 14.2.