Allow FlexibleArray with union array data

BeefLibs/corlib/src/Interop.bf

@@ -89,7 +89,7 @@ namespace System
 			}
 		}
 
-		[AttributeUsage(.Struct)]
+		[AttributeUsage(.Struct, .DisallowAllowMultiple)]
 		struct FlexibleArrayAttribute : Attribute, IOnTypeInit
 		{
 			String mName;
@@ -99,20 +99,61 @@ namespace System
 				mName = name;
 			}
 
+			public this(params Span<String> names)
+			{
+				mName = new String();
+				for (var name in names)
+				{
+					if (!mName.IsEmpty)
+						mName.Append("\n");
+					mName.Append(name);
+				}
+			}
+
 			[Comptime]
 			public void OnTypeInit(Type type, Self* prev)
 			{
 				if (type.IsGenericParam)
 					return;
 				var field = type.GetField(type.FieldCount - 1).GetValueOrDefault();
-				if ((field.FieldType == null) || (!field.FieldType.IsSizedArray) || (field.FieldType.Size != 0))
-					Runtime.FatalError("Type must end in a zero-sized array");
-				var elementType = (field.FieldType as SizedArrayType).UnderlyingType;
-				Compiler.Align(type, elementType.Align);
-				Compiler.EmitTypeBody(type, scope $"""
-					public {elementType}* {mName} mut => (({elementType}*)((uint8*)&this + Math.Align(typeof(Self).Size, typeof({elementType}).Align)));
-					public static int GetAllocSize(int arrayCount) => Math.Align(typeof(Self).Size, typeof({elementType}).Align) + typeof({elementType}).Size*arrayCount;
-					""");
+				if (field.FieldType?.IsUnion == true)
+				{
+					int diff = 0;
+					for (var unionField in field.FieldType.GetFields(.Instance))
+						diff++;
+					for (var names in mName.Split('\n'))
+						diff--;
+					if (diff != 0)
+						Runtime.FatalError("Incorrect number of names specified");
+
+					var nameItr = mName.Split('\n');
+					for (var unionField in field.FieldType.GetFields(.Instance))
+					{
+						var name = nameItr.GetNext().Value;
+						if ((!unionField.FieldType.IsSizedArray) || (unionField.FieldType.Size != 0))
+							Runtime.FatalError(scope $"Union field '{unionField.Name}' must be a zero-sized array");
+						var elementType = (unionField.FieldType as SizedArrayType).UnderlyingType;
+						Compiler.Align(type, elementType.Align);
+						Compiler.EmitTypeBody(type, scope $"""
+							public {elementType}* {name} mut => (({elementType}*)((uint8*)&this + typeof(Self).Size));
+							public static int GetAllocSize_{name}(int arrayCount) => typeof(Self).Size + typeof({elementType}).Size*arrayCount;
+
+							""");
+					}
+				}
+				else
+				{
+					if (mName.Contains('\n'))
+						Runtime.FatalError("Only a single accessor name expected");
+					if ((field.FieldType == null) || (!field.FieldType.IsSizedArray) || (field.FieldType.Size != 0))
+						Runtime.FatalError("Type must end in a zero-sized array");
+					var elementType = (field.FieldType as SizedArrayType).UnderlyingType;
+					Compiler.Align(type, elementType.Align);
+					Compiler.EmitTypeBody(type, scope $"""
+						public {elementType}* {mName} mut => (({elementType}*)((uint8*)&this + typeof(Self).Size));
+						public static int GetAllocSize(int arrayCount) => typeof(Self).Size + typeof({elementType}).Size*arrayCount;
+						""");
+				}
 			}
 		}
 	}

IDEHelper/Compiler/BfModule.cpp

@@ -11777,6 +11777,14 @@ BfIRValue BfModule::ConstantToCurrent(BfConstant* constant, BfIRConstHolder* con
 				newVals.Add(ConstantToCurrent(constHolder->GetConstant(val), constHolder, elementType));
 			}
 		}
+		else if (wantType->IsInstanceOf(mCompiler->mSpanTypeDef))
+		{
+			auto elementType = wantType->GetUnderlyingType();
+			for (auto val : constArray->mValues)
+			{
+				newVals.Add(ConstantToCurrent(constHolder->GetConstant(val), constHolder, elementType));
+			}
+		}
 		else
 		{
 			auto wantTypeInst = wantType->ToTypeInstance();