[clang] Add tests for CWG issues 6, 212, 232, 2823. (PR #165633)

[Aaron Ballman via cfe-commits]

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@@ -61,6 +61,24 @@ namespace cwg2819 { // cwg2819: 19 c++26
 #endif
 } // namespace cwg2819
 
+namespace cwg2823 { // cwg2823: no
+#if __cplusplus >= 201103L
+  constexpr int *p = 0;
+  constexpr int *q1 = &*p;
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AaronBallman wrote:

Yup, agreed that's a Clang bug (and a recent regression, from the looks of it); I filed https://github.com/llvm/llvm-project/issues/168707 to track it. Thanks!

https://github.com/llvm/llvm-project/pull/165633