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From: "aschepler at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/98440] New: Accepts ill-formed reinterpret_cast<int&&>(1)
Date: Thu, 24 Dec 2020 21:38:53 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D98440

            Bug ID: 98440
           Summary: Accepts ill-formed reinterpret_cast<int&&>(1)
           Product: gcc
           Version: 10.2.0
            Status: UNCONFIRMED
          Keywords: accepts-invalid
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: aschepler at gmail dot com
  Target Milestone: ---

g++ does not give any error or warning for a reinterpret_cast when the targ=
et
type is an rvalue reference type and the expression operand is a prvalue, f=
or
example reinterpret_cast<int&&>(1).

In standard section [expr.reinterpret.cast], casts to reference types are
described only by paragraph 11, which allows casting a glvalue to a referen=
ce
type, but specifically says "No temporary is created". So the temporary
materialization conversion can't be implicitly used like in most expression=
s,
and the paragraph can't apply.

Clang++, MSVC, and ICC all produce error messages for the expression
reinterpret_cast<int&&>(1).=