[clang] [clang] Add the candiscard attribute to suppress nodiscard (PR #154943)

[via cfe-commits]

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@@ -199,6 +199,10 @@ Removed Compiler Flags
 
 Attribute Changes in Clang
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+- A new attribute ``[[clang::candiscard]]`` can be applied to a function returning a nodiscard type
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yronglin wrote:

`discardable` looks good to me.

https://github.com/llvm/llvm-project/pull/154943