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From: "roi.jacobson1 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/104615] New: [Concepts] ICE in explicit instantiation when
 multiple candidates are valid (CWG2421)
Date: Mon, 21 Feb 2022 17:35:08 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104615

            Bug ID: 104615
           Summary: [Concepts] ICE in explicit instantiation when multiple
                    candidates are valid (CWG2421)
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: roi.jacobson1 at gmail dot com
  Target Milestone: ---

#include <concepts>
template<class T>
struct B {
    int f() requires (!std::same_as<T, char>) {
        return 0;
    }
    int f() requires (!std::same_as<T, char> && !std::same_as<T, float>) {
        return 1;
    }
};
template struct B<int>;


This crashes GCC with "<source>:12:23: error: Two symbols with same
comdat_group are not linked by the same_comdat_group list." as both functio=
ns
are compiled and have the same mangling.

Also, CWG2421 is still open about what the actual behavior should be in this
case.=