[llvm] [ADT] Fix llvm::concat_iterator for `ValueT == common_base_class *` (PR #144744)

[Javier Lopez-Gomez via llvm-commits]

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@@ -1088,7 +1089,7 @@ class concat_iterator
     if (Begin == End)
       return {};
 
-    if constexpr (ReturnsByValue)
+    if constexpr (ReturnsValueOrPointer)
       return *Begin;
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jalopezg-git wrote:

Yeah, let me give it another round of work - this week is WG21 meeting; I was in a hurry but still wanted to open a draft PR.

https://github.com/llvm/llvm-project/pull/144744