[error] Reject attempts to copy object storage.

Fix #176

Sema.fu

@@ -1088,6 +1088,9 @@ public class FuSema
 		case FuToken.Assign:
 			CheckLValue(left);
 			CoercePermanent(right, left.Type);
+			if (left.Type is FuStorageType && right is FuSymbolReference
+				&& !(left is FuSymbolReference symbol && symbol.Symbol is FuNamedValue storageDef && storageDef.IsAssignableStorage()))
+				ReportError(right, "Cannot copy object storage");
 			SetSharedAssign(left, right);
 			expr.Left = left;
 			expr.Right = right;
@@ -1462,6 +1465,8 @@ public class FuSema
 						if (!(expr.Value is FuLiteral literal) || !literal.IsDefaultValue())
 							ReportError(expr.Value, "Only null, zero and false supported as an array initializer");
 					}
+					else if (type is FuStorageType && expr.Value is FuSymbolReference)
+						ReportError(expr.Value, "Cannot copy object storage");
 					CoercePermanent(expr.Value, type);
 				}
 			}

libfut.cpp

@@ -5601,11 +5601,17 @@ std::shared_ptr<FuExpr> FuSema::visitBinaryExpr(std::shared_ptr<FuBinaryExpr> ex
 	case FuToken::assign:
 		checkLValue(left.get());
 		coercePermanent(right.get(), left->type.get());
-		setSharedAssign(left.get(), right.get());
-		expr->left = left;
-		expr->right = right;
-		expr->type = left->type;
-		return expr;
+		{
+			const FuSymbolReference * symbol;
+			const FuNamedValue * storageDef;
+			if (dynamic_cast<const FuStorageType *>(left->type.get()) && dynamic_cast<const FuSymbolReference *>(right.get()) && !((symbol = dynamic_cast<const FuSymbolReference *>(left.get())) && (storageDef = dynamic_cast<const FuNamedValue *>(symbol->symbol)) && storageDef->isAssignableStorage()))
+				reportError(right.get(), "Cannot copy object storage");
+			setSharedAssign(left.get(), right.get());
+			expr->left = left;
+			expr->right = right;
+			expr->type = left->type;
+			return expr;
+		}
 	case FuToken::addAssign:
 		checkLValue(left.get());
 		if (left->type->id == FuId::stringStorageType)
@@ -5998,6 +6004,8 @@ void FuSema::visitVar(std::shared_ptr<FuVar> expr)
 					if (!(literal = dynamic_cast<const FuLiteral *>(expr->value.get())) || !literal->isDefaultValue())
 						reportError(expr->value.get(), "Only null, zero and false supported as an array initializer");
 				}
+				else if (dynamic_cast<const FuStorageType *>(type) && dynamic_cast<const FuSymbolReference *>(expr->value.get()))
+					reportError(expr->value.get(), "Cannot copy object storage");
 				coercePermanent(expr->value.get(), type);
 			}
 		}

libfut.cs

@@ -5743,6 +5743,8 @@ FuExpr VisitBinaryExpr(FuBinaryExpr expr)
 			case FuToken.Assign:
 				CheckLValue(left);
 				CoercePermanent(right, left.Type);
+				if (left.Type is FuStorageType && right is FuSymbolReference && !(left is FuSymbolReference symbol && symbol.Symbol is FuNamedValue storageDef && storageDef.IsAssignableStorage()))
+					ReportError(right, "Cannot copy object storage");
 				SetSharedAssign(left, right);
 				expr.Left = left;
 				expr.Right = right;
@@ -6097,6 +6099,8 @@ void VisitVar(FuVar expr)
 							if (!(expr.Value is FuLiteral literal) || !literal.IsDefaultValue())
 								ReportError(expr.Value, "Only null, zero and false supported as an array initializer");
 						}
+						else if (type is FuStorageType && expr.Value is FuSymbolReference)
+							ReportError(expr.Value, "Cannot copy object storage");
 						CoercePermanent(expr.Value, type);
 					}
 				}

libfut.js

@@ -6043,6 +6043,10 @@ export class FuSema
 		case FuToken.ASSIGN:
 			this.#checkLValue(left);
 			this.#coercePermanent(right, left.type);
+			let symbol;
+			let storageDef;
+			if (left.type instanceof FuStorageType && right instanceof FuSymbolReference && !((symbol = left) instanceof FuSymbolReference && (storageDef = symbol.symbol) instanceof FuNamedValue && storageDef.isAssignableStorage()))
+				this.#reportError(right, "Cannot copy object storage");
 			this.#setSharedAssign(left, right);
 			expr.left = left;
 			expr.right = right;
@@ -6430,6 +6434,8 @@ export class FuSema
 						if (!((literal = expr.value) instanceof FuLiteral) || !literal.isDefaultValue())
 							this.#reportError(expr.value, "Only null, zero and false supported as an array initializer");
 					}
+					else if (type instanceof FuStorageType && expr.value instanceof FuSymbolReference)
+						this.#reportError(expr.value, "Cannot copy object storage");
 					this.#coercePermanent(expr.value, type);
 				}
 			}

test/error/ObjectStgCopy.fu

@@ -0,0 +1,11 @@
+public class Test
+{
+	public static bool Run()
+	{
+		Test() o;
+		Test() c = o; //ERROR: Cannot copy object storage
+		Test() t;
+		t = o; //ERROR: Cannot copy object storage
+		return true;
+	}
+}