[clang] [clang] Generate note on declaration for nodiscard-related attributes (PR #112289)

[Erich Keane via cfe-commits]

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@@ -9290,6 +9290,8 @@ def warn_unused_result_typedef_unsupported_spelling : Warning<
 def warn_unused_volatile : Warning<
   "expression result unused; assign into a variable to force a volatile load">,
   InGroup<DiagGroup<"unused-volatile-lvalue">>;
+def note_nodiscard_specified_here : Note<
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erichkeane wrote:

Either a string parameter, or add another select entry/ies.  Thats easy enough. An alternative is to add an enum for them with an operator << overload available.

https://github.com/llvm/llvm-project/pull/112289