[llvm] [EquivClasses] Introduce members iterator-helper (NFC) (PR #130139)

[Florian Hahn via llvm-commits]

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@@ -178,6 +178,9 @@ class EquivalenceClasses {
   member_iterator member_end() const {
     return member_iterator(nullptr);
   }
+  auto members(iterator I) const {
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fhahn wrote:

Could you spell out the type here as is generally preferred in LLVM unless not possible otherwise?

https://github.com/llvm/llvm-project/pull/130139