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From: "nathan at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/96363] New: bogus error with constrained partial
 specialization
Date: Tue, 28 Jul 2020 21:50:30 +0000
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X-Bugzilla-Component: c++
X-Bugzilla-Version: 10.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D96363

            Bug ID: 96363
           Summary: bogus error with constrained partial specialization
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nathan at gcc dot gnu.org
  Target Milestone: ---

template <typename T> class TPL;

template <typename T> struct Trait;

template <typename T>
  requires (Trait<T>::val =3D=3D 0)
class TPL<T>;  // #1

template <typename T>
  requires (Trait<T>::val =3D=3D 1)
class TPL<T>;  // #2 error here

cc1plus -quiet -std=3Dc++20 par.cc=20
par.cc:11:7: error: =E2=80=98TPL<T>=E2=80=99 does not match original declar=
ation
   11 | class TPL<T>;
      |       ^~~~~~
par.cc:1:29: note: original template declaration here
    1 | template <typename T> class TPL;
      |                             ^~~

ICBW, but if #2 is rejected, why is #1 accepted.  Aren't these just two par=
tial
specializations with different constraints?=