[lldb] [llvm] [lldb] Fix GetIndexOfChildWithName on register sets (PR #212727)

[David Spickett via llvm-commits]

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@@ -113,6 +113,17 @@ Makes programs 10x faster by doing Special New Thing.
 
 ### Changes to LLDB
 
+#### SBAPI
+
+* A [bug](https://github.com/llvm/llvm-project/issues/211787) involving SBValues
+  representing a register set was fixed. The methods `GetIndexOfChildWithName`
+  and `GetChildMemberWithName` were incorrectly looking up values in all
+  register sets. This meant that `GetIndexOfChildWithName` could return an index
+  greater than the size of the set, and that `GetChildMemberWithName` could
+  return values that were actually in a different set. Both methods are now fixed
+  so that they are limited to the registers within the register set. Scripts
+  using these methods may have to be updated as a result.
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DavidSpickett wrote:

I wouldn't normally release note a bug fix but since the behaviour could silently change I thought it best to do so.

I think we're justified in fixing it because GetNumChildren always reported the same number, and it now works in the way a reasonable person would expect. But existing scripts might do some strange things.

https://github.com/llvm/llvm-project/pull/212727