[llvm] [ADT] Add `[[clang::lifetimebound]]` annotations to Twine.h (PR #210474)

[via llvm-commits]

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@@ -470,8 +479,8 @@ class Twine {
   /// given SmallVector and a StringRef to the SmallVector's data is returned.
   ///
   /// The returned StringRef's size does not include the null terminator.
-  LLVM_ABI StringRef
-  toNullTerminatedStringRef(SmallVectorImpl<char> &Out) const;
+  LLVM_ABI StringRef toNullTerminatedStringRef(
+      SmallVectorImpl<char> &Out LLVM_LIFETIME_BOUND) const;
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isuckatcs wrote:

> Yes, you are right based on the comment:

Please don't annotate based on comments in the source code. Annotate it based on the definition. In this case the comment reflects the definition, but it might not always be the case.

https://github.com/llvm/llvm-project/pull/210474