[llvm] [Transforms] Use range-based for loops (NFC) (PR #97195)

[Matt Arsenault via llvm-commits]

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@@ -226,9 +226,7 @@ static bool mergeConstants(Module &M) {
     // Now that we have figured out which replacements must be made, do them all
     // now.  This avoid invalidating the pointers in CMap, which are unneeded
     // now.
-    for (unsigned i = 0, e = SameContentReplacements.size(); i != e; ++i) {
-      GlobalVariable *Old = SameContentReplacements[i].first;
-      GlobalVariable *New = SameContentReplacements[i].second;
+    for (const auto &[Old, New] : SameContentReplacements) {
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arsenm wrote:

I don't understand this warning. It sounds useless 

https://github.com/llvm/llvm-project/pull/97195