[clang] [llvm] [EquivalenceClasses] Use SmallVector for deterministic iteration order. (PR #134075)

[Matt Arsenault via llvm-commits]

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@@ -138,6 +139,9 @@ class EquivalenceClasses {
   /// ECValues, it just keeps the key as part of the value.
   std::set<ECValue, ECValueComparator> TheMapping;
 
+  /// List of all members, used to provide a determinstic iteration order.
+  SmallVector<const ECValue *> Members;
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arsenm wrote:

Can you combine into SetVector? 

https://github.com/llvm/llvm-project/pull/134075