65816 now generate EXPR_NEARADDR instead of EXPR_WORD0 for default assumed address mode, which will be validated by the linker's range check rather than blindly truncated. Assuming the assembler correctly validated this, the linker is allowed to truncate.

src/ld65/expr.c

@@ -436,6 +436,10 @@ long GetExprVal (ExprNode* Expr)
         case EXPR_WORD1:
             return (GetExprVal (Expr->Left) >> 16) & 0xFFFF;
 
+        case EXPR_NEARADDR:
+            /* Assembler was expected to validate this truncation. */
+            return GetExprVal (Expr->Left) & 0xFFFF;
+
         case EXPR_FARADDR:
             return GetExprVal (Expr->Left) & 0xFFFFFF;