[clang] [clang] Improve diagnostic on [[nodiscard]] attribute (PR #112521)

[Yihe Li via cfe-commits]

================
@@ -115,20 +115,20 @@ void usage() {
   S('A'); // expected-warning {{ignoring temporary created by a constructor declared with 'nodiscard' attribute: Don't let that S-Char go!}}
   S(1);
   S(2.2);
-  Y(); // expected-warning {{ignoring temporary created by a constructor declared with 'nodiscard' attribute: Don't throw me away either!}}
+  Y(); // expected-warning {{ignoring temporary of type 'Y' declared with 'nodiscard' attribute: Don't throw me away either!}}
   S s;
-  ConvertTo{}; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute: Don't throw me away!}}
+  ConvertTo{}; // expected-warning {{ignoring return value of type 'ConvertTo' declared with 'nodiscard' attribute: Don't throw me away!}}
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Mick235711 wrote:

Yeah, definitely because of that, since the following also gives two different warnings ([CE](https://godbolt.org/z/rPb5jaY1x)):
```cpp
struct [[nodiscard]] A {};
void use()
{
    A();
    A{};
}
```
This probably is not intended (I hope), but I'm not familiar enough with related infrastructure to suggest a fix. Either way, that is not in the scope of this PR.

https://github.com/llvm/llvm-project/pull/112521