Rollup merge of rust-lang#158568 - liza371:llvm-23-compat, r=nikic

llvm-wrapper: use accessors for private fields in LLVM 23+

In LLVM, FeatureKV/SubtargetKV pointers are now private:
llvm/llvm-project#206237
This change fixes compiler errors when building rustc with ToT LLVM
by using the key() and desc() accessors.

Author: JonathanBrouwer

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -288,7 +288,11 @@ extern "C" void LLVMRustPrintTargetCPUs(LLVMTargetMachineRef TM,
   // Just print a bare list of target CPU names, and let Rust-side code handle
   // the full formatting of `--print=target-cpus`.
   for (auto &CPU : CPUTable) {
+#if LLVM_VERSION_GE(23, 0)
+    OS << CPU.key() << "\n";
+#else
     OS << CPU.Key << "\n";
+#endif
   }
 }
 
@@ -315,9 +319,15 @@ extern "C" void LLVMRustGetTargetFeature(LLVMTargetMachineRef TM, size_t Index,
 #endif
   const ArrayRef<SubtargetFeatureKV> FeatTable =
       MCInfo.getAllProcessorFeatures();
+#if LLVM_VERSION_GE(23, 0)
+  const SubtargetFeatureKV &Feat = FeatTable[Index];
+  *Feature = Feat.key();
+  *Desc = Feat.desc();
+#else
   const SubtargetFeatureKV Feat = FeatTable[Index];
   *Feature = Feat.Key;
   *Desc = Feat.Desc;
+#endif
 }
 
 extern "C" const char *LLVMRustGetHostCPUName(size_t *OutLen) {