[clang] [CIR] Upstream CIR method attribute handling (PR #174640)

[Erich Keane via cfe-commits]

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@@ -133,4 +137,48 @@ mlir::Operation *LowerItaniumCXXABI::lowerGetRuntimeMember(
                              cir::CastKind::bitcast, memberBytesPtr);
 }
 
+mlir::TypedAttr LowerItaniumCXXABI::lowerMethodConstant(
+    cir::MethodAttr attr, const mlir::DataLayout &layout,
+    const mlir::TypeConverter &typeConverter) const {
+  cir::IntType ptrdiffCIRTy = getPtrDiffCIRTy(lm);
+  auto loweredMethodTy = mlir::cast<cir::RecordType>(
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erichkeane wrote:

Why are we doing `lowerMethodType`  and getting a `RecordType` back?  Is that weird? 

https://github.com/llvm/llvm-project/pull/174640