[llvm] [MC] Use range-based for loops (NFC) (PR #139354)

[Shilei Tian via llvm-commits]

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@@ -477,10 +477,10 @@ MCSymbolXCOFF *MCContext::createXCOFFSymbolImpl(const MCSymbolTableEntry *Name,
 
   // Append the hex values of '_' and invalid characters with "_Renamed..";
   // at the same time replace invalid characters with '_'.
-  for (size_t I = 0; I < InvalidName.size(); ++I) {
-    if (!MAI->isAcceptableChar(InvalidName[I]) || InvalidName[I] == '_') {
-      raw_svector_ostream(ValidName).write_hex(InvalidName[I]);
-      InvalidName[I] = '_';
+  for (char &I : InvalidName) {
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shiltian wrote:

I'd call it `C`.

https://github.com/llvm/llvm-project/pull/139354