[clang] [clang]improve diagnosing redefined defaulted constructor with different exception specs (PR #69688)

[Congcong Cai via cfe-commits]

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@@ -378,7 +381,6 @@ Improvements to Clang's diagnostics
   C++ semantics, e.g. which function template is more specialized. This
   can sometimes lead to worse ordering.
 
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HerrCai0907 wrote:

```suggestion

```

https://github.com/llvm/llvm-project/pull/69688