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From: "StevenSun2021 at hotmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/108218] New: [12 Regression] Constant arguments in the new
 expression is not checked in unevaluated operand
Date: Sat, 24 Dec 2022 15:52:56 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 12.1.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108218

            Bug ID: 108218
           Summary: [12 Regression] Constant arguments in the new
                    expression is not checked in unevaluated operand
           Product: gcc
           Version: 12.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: StevenSun2021 at hotmail dot com
  Target Milestone: ---

```
int main() {
    decltype(new int[-1]) a; // compiles with g++-12! <- regression here
                             // does not compile with g++-11


    auto b =3D new int[-1];    // does not compile with g++-12
                             // does not compile with g++-11
}
```
https://godbolt.org/z/aMGMrbfrd


expected behavior:
if, after conversion to std::size_t, the first dimension is a core constant
expression and it is potentially evaluated, the program is ill-formed.
https://en.cppreference.com/w/cpp/language/new

gcc(<=3D11.3 (current version)) and clang(>=3D3) does this check.=