<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/145956>145956</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang] For-range with structured bindings during constant evaluation
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          katzdm
      </td>
    </tr>
</table>

<pre>
    As far as I can tell, the following should be well-formed:

```cpp
consteval auto f() -> int {
    struct Pair { int first; int second; };

    Pair arr[] = {{1, 1}};
    for (auto const& [key, value] : arr) {
        [=] { [[maybe_unused]] int s = key; }();
    }
    return 0;
}

int p = f();
```
https://compiler-explorer.com/z/5cGfrMTd7

GCC and MSVC accept; Clang and EDG reject, but EDG has acknowledged their behavior as a bug.

I did some preliminary digging, and the issue looks to occur while computing the lvalue-to-rvalue conversion of the `DeclRefExpr` that names `key` in the initializer of `s`; the `findCompleteObject` routine seems to be tripping over the structured binding and returns an empty `CompleteObject` [here](https://github.com/llvm/llvm-project/blob/a0c5f1992d2188dd58987445aa00a55edad2357f/clang/lib/AST/ExprConstant.cpp#L4488).
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJyUVE2P2zYQ_TX0ZWCDpr4POvhjvQjQoEUT9FpQ4khilyIFkvJm99cXQ3mbFO0lhgCL5MybN_OeKEPQo0VsWXFmxXUn1zg5377I-K7mXefUW3sKMEgPMsAn6KWFiMYwcYE4IQzOGPeq7QhhcqtR0CG8ojH7wfkZFctOjKen5NvTLwvjp97ZEPEuDcg1OhiYqJloYM-yJ9A2AqvOjJ8AAEL0ax_hN6k97abTQfsQWbYtAvbOKlqx6sqy81aPUlOO9H7rDFh2TbjV-UjsjxT-kUHhg_PARJ0IJX5MlMCK8wu-UfxdmhU3nFNCFc0PNOlHdbJrCqnOaVWcZ_nW4Z-rXQMqVqTDRDqxIeQH79T_dy60tb15jKu3wB-dpX3GTwSyJJDhx9x_xsz4aYpxCSSAuDFx6928aIN-j98W4zz6Q-9mJm7vTNyK_nnwn7-qasN-vlxAWgWfv_xxAdn3uKRhX4y0Yzp4uj6Dx7-wjzSYbo1pZ5IBZP9i3atBNaIif2gPHU7yrl3yj4RuHQ9blU-gtILgZoTFo9GzttK_gdLjqO1IwFSKPKZDWBGMcy8BogPX96uH10kbBOpqjWQ_CjRJo310e5_eSMY7-qCdBTekEFbyK_bmdxyevi2elRziJCNYOWOgQ5Kk5KDtVtnqqKXR7-gJgJU80Gyz8wfWoK26uHkxGPHXLk2k5OAdcUIIiHOi3CFEr5eFiLo7-pS-OXv1qKDTVunHcDfBA0gLOC_xjcr8twQrzhN68iMT9b-VHnWc1u4hrzH3j7_94t2m2a0zrmPiJnlfDMemEUoc61qpom7qKs8LKTmXRYFKKpEV1UD2IfEJSFPi6ctXJm40wQt9KNLGA33XIvslz2ty42Gn2kw1WSN32B6rgjdlWZR8N7UK5XHIlMp7VRfymKuqamRTF1XXZYPqqp1uBRcFL0V5bLKS88NQiuMgZVc3dV_Vec5yjrPU5kBNHZwfd8kg7TEvmqLcGdmhCek6E-JBW9DN5ts0hW4dA8u50SGG7xBRR5PuwC2juMLN-b2XdkR41XH6H7UCqNWTav1jBkAX2iqjdna3etP-tCypj8DE7dHKvRV_BwAA___2vcBz">