Swift SIL: add NominalFieldsArray.getNameOfField(withIndex:)

Author: eeckstein

SwiftCompilerSources/Sources/SIL/Type.swift

@@ -80,6 +80,10 @@ public struct NominalFieldsArray : RandomAccessCollection, FormattedLikeArray {
     }
     return idx >= 0 ? idx : nil
   }
+
+  public func getNameOfField(withIndex idx: Int) -> StringRef {
+    StringRef(bridged: SILType_getNominalFieldName(type.bridged, idx))
+  }
 }
 
 public struct TupleElementArray : RandomAccessCollection, FormattedLikeArray {

include/swift/SIL/SILBridging.h

@@ -274,6 +274,7 @@ BridgedType SILType_getNominalFieldType(BridgedType type, SwiftInt index,
                                         BridgedFunction function);
 SwiftInt SILType_getFieldIdxOfNominalType(BridgedType type,
                                           llvm::StringRef fieldName);
+llvm::StringRef SILType_getNominalFieldName(BridgedType type, SwiftInt index);
 SwiftInt SILType_getCaseIdxOfEnumType(BridgedType type,
                                       llvm::StringRef caseName);
 

lib/SIL/Utils/SILBridging.cpp

@@ -461,6 +461,14 @@ BridgedType SILType_getNominalFieldType(BridgedType type, SwiftInt index,
   return {fieldType.getOpaqueValue()};
 }
 
+StringRef SILType_getNominalFieldName(BridgedType type, SwiftInt index) {
+  SILType silType = castToSILType(type);
+
+  NominalTypeDecl *decl = silType.getNominalOrBoundGenericNominal();
+  VarDecl *field = getIndexedField(decl, (unsigned)index);
+  return field->getName().str();
+}
+
 SwiftInt SILType_getFieldIdxOfNominalType(BridgedType type,
                                           StringRef fieldName) {
   SILType ty = castToSILType(type);