[clang] [LifetimeSafety] Warn on meaningless [[clang::lifetimebound]] parameters (PR #201101)

[Gábor Horváth via cfe-commits]

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@@ -631,6 +631,13 @@ This warning may produce false-positives diagnostics when it cannot fully model
   }];
 }
 
+def LifetimeSafetyMeaninglessLifetimebound
+    : DiagGroup<"lifetime-safety-meaningless-lifetimebound"> {
+  code Documentation = [{
+Detects uses of [[clang::lifetimebound]] that have no effect because the annotated type cannot carry a lifetime.
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Xazax-hun wrote:

Nit: strictly speaking, the `lifetimebound` annotation is not a type annotation, so referring to the "annotated type" is not correct. 

I think we could use terminology like "the type of the annotated parameter" or "the type of the annotated implicit object parameter" depending on the kind of annotation instead. 

https://github.com/llvm/llvm-project/pull/201101