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

[Benedek Kaibas via llvm-commits]

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@@ -254,7 +256,7 @@ class Twine {
   /// We take care here to optimize "" into the empty twine -- this will be
   /// optimized out for string constants. This allows Twine arguments have
   /// default "" values, without introducing unnecessary string constants.
-  /*implicit*/ Twine(const char *Str) {
+  /*implicit*/ Twine(const char *Str LLVM_LIFETIME_BOUND) {
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benedekaibas wrote:

I think it would make more sense to add annotation incrementally and only annotate the functions that we for sure know won't introduce FPs. I will think about this more and do a commit for it tomorrow.

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