diff --git a/stage0/test_spl_vm.c b/stage0/test_spl_vm.c
index 27e9705..d080d10 100644
--- a/stage0/test_spl_vm.c
+++ b/stage0/test_spl_vm.c
@@ -476,7 +476,7 @@ void test_call_add(void) {
      *   ret i64     ip=10
      */
     spl_ins_t add_insns[] = {ins(SPL_LADDR, SPL_VOID, 0), ins(SPL_LOAD, SPL_I64, 0),
-                             ins(SPL_LADDR, SPL_VOID, 1), ins(SPL_LOAD, SPL_I64, 0),
+                             ins(SPL_LADDR, SPL_VOID, 8), ins(SPL_LOAD, SPL_I64, 0),
                              ins(SPL_ADD, SPL_I64, 0),    ins(SPL_RET, SPL_I64, 0)};
     spl_ins_t main_insns[] = {ins(SPL_PUSH, SPL_I32, 10), ins(SPL_PUSH, SPL_I32, 20),
                               ins(SPL_PUSH, SPL_VOID, 0), ins(SPL_CALL, SPL_VOID, 2),
@@ -583,7 +583,7 @@ void test_calli(void) {
      *   ret i64     ip=11
      */
     spl_ins_t add_insns[] = {ins(SPL_LADDR, SPL_VOID, 0), ins(SPL_LOAD, SPL_I64, 0),
-                             ins(SPL_LADDR, SPL_VOID, 1), ins(SPL_LOAD, SPL_I64, 0),
+                             ins(SPL_LADDR, SPL_VOID, 8), ins(SPL_LOAD, SPL_I64, 0),
                              ins(SPL_ADD, SPL_I64, 0),    ins(SPL_RET, SPL_I64, 0)};
     spl_ins_t main_insns[] = {ins(SPL_PUSH, SPL_I32, 10),  ins(SPL_PUSH, SPL_I32, 20),
                               ins(SPL_PUSH, SPL_VOID, 2),  ins(SPL_PUSH, SPL_VOID, 0),
diff --git a/stage1/spl_comp.c b/stage1/spl_comp.c
index ac04a92..76e1fb8 100644
--- a/stage1/spl_comp.c
+++ b/stage1/spl_comp.c
@@ -107,7 +107,7 @@ void spl_patch_to_here(spl_comp_t *ctx, spl_val_t addr) {
     spl_patch(ctx, addr, offset);
 }
 
-/* ---- Multi-slot copy helper ---- */
+/* ---- Multi-slot copy helpers ---- */
 
 void spl_emit_copy_slots(spl_comp_t *ctx, int dest_offset, usize nslots) {
     for (usize i = 0; i < nslots; i++) {
@@ -124,6 +124,31 @@ void spl_emit_copy_slots(spl_comp_t *ctx, int dest_offset, usize nslots) {
     }
 }
 
+/* Copy nslots from source address to destination address.
+ * Stack before: [..., depth_items..., dest_addr, src_addr] (src TOS)
+ * Stack after: [..., depth_items...]
+ * depth: number of items below dest_addr that must be preserved (e.g. 1 if
+ *        there's a base pointer between the rest of the stack and dest_addr). */
+void spl_emit_copy_addr_to_addr(spl_comp_t *ctx, usize nslots, int depth) {
+    for (usize i = 0; i < nslots; i++) {
+        spl_emit(ctx, SPL_DUP, SPL_VOID, 0);
+        if (i > 0) {
+            spl_emit(ctx, SPL_PUSH, SPL_USIZE, i * sizeof(spl_val_t));
+            spl_emit(ctx, SPL_ADD, SPL_USIZE, 0);
+        }
+        spl_emit(ctx, SPL_LOAD, SPL_PTR, 0);
+        spl_emit(ctx, SPL_PICK, SPL_VOID, 2 + depth);
+        if (i > 0) {
+            spl_emit(ctx, SPL_PUSH, SPL_USIZE, i * sizeof(spl_val_t));
+            spl_emit(ctx, SPL_ADD, SPL_USIZE, 0);
+        }
+        spl_emit(ctx, SPL_SWAP, SPL_VOID, 0);
+        spl_emit(ctx, SPL_STORE, SPL_PTR, 0);
+    }
+    spl_emit(ctx, SPL_DROP, SPL_VOID, 0);
+    spl_emit(ctx, SPL_DROP, SPL_VOID, 0);
+}
+
 /* ---- Uniform LOAD/STORE type helper ---- */
 
 spl_type_t spl_type_emit_type(spl_type_info_t *type) {
@@ -165,17 +190,22 @@ int spl_type_is_scalar(spl_type_info_t *type) {
 
 void spl_emit_load_to_var(spl_comp_t *ctx, int ptr_slot_offset, usize byte_offset,
                           spl_type_info_t *data_type, int var_offset) {
-    spl_type_t bt = spl_type_emit_type(data_type);
     spl_emit(ctx, SPL_LADDR, SPL_PTR, ptr_slot_offset);
     spl_emit(ctx, SPL_LOAD, SPL_PTR, 0);
     if (byte_offset > 0) {
         spl_emit(ctx, SPL_PUSH, SPL_USIZE, byte_offset);
         spl_emit(ctx, SPL_ADD, SPL_USIZE, 0);
     }
-    spl_emit(ctx, SPL_LOAD, bt, 0);
-    spl_emit(ctx, SPL_LADDR, SPL_PTR, var_offset);
-    spl_emit(ctx, SPL_SWAP, SPL_VOID, 0);
-    spl_emit(ctx, SPL_STORE, bt, 0);
+    if (data_type && !spl_type_is_scalar(data_type) &&
+        spl_type_size(data_type) > sizeof(spl_val_t)) {
+        spl_emit_copy_slots(ctx, var_offset, spl_type_slot_count(data_type));
+    } else {
+        spl_type_t bt = spl_type_emit_type(data_type);
+        spl_emit(ctx, SPL_LOAD, bt, 0);
+        spl_emit(ctx, SPL_LADDR, SPL_PTR, var_offset);
+        spl_emit(ctx, SPL_SWAP, SPL_VOID, 0);
+        spl_emit(ctx, SPL_STORE, bt, 0);
+    }
 }
 
 /* ---- Scope management ---- */
diff --git a/stage1/spl_comp.h b/stage1/spl_comp.h
index e30ba79..e36dc4b 100644
--- a/stage1/spl_comp.h
+++ b/stage1/spl_comp.h
@@ -287,6 +287,7 @@ void spl_patch_to_here(spl_comp_t *ctx, spl_val_t addr);
  * Stack: [..., temp_addr] → [...]
  * Copies nslots slots (each sizeof(spl_val_t) bytes) from temp offset to dest_offset. */
 void spl_emit_copy_slots(spl_comp_t *ctx, int dest_offset, usize nslots);
+void spl_emit_copy_addr_to_addr(spl_comp_t *ctx, usize nslots, int depth);
 void spl_emit_ret(spl_comp_t *ctx, spl_type_info_t *ret_type);
 void spl_emit_store_init(spl_comp_t *ctx, int var_offset, spl_type_info_t *var_type);
 
diff --git a/stage1/spl_expr.c b/stage1/spl_expr.c
index ab0cda4..e79d5fb 100644
--- a/stage1/spl_expr.c
+++ b/stage1/spl_expr.c
@@ -457,7 +457,11 @@ static void parse_one_field_init(spl_comp_t *ctx, spl_field_vec_t *fields, int b
                         spl_emit(ctx, SPL_ADD, SPL_USIZE, 0);
                     }
                     spl_parse_expr(ctx, PREC_MIN);
-                    spl_emit(ctx, SPL_STORE, st, 0);
+                    if (elem_type && !spl_type_is_scalar(elem_type)) {
+                        spl_emit_copy_addr_to_addr(ctx, spl_type_slot_count(elem_type), 1);
+                    } else {
+                        spl_emit(ctx, SPL_STORE, st, 0);
+                    }
                     skip_nl(ctx);
                 }
                 if (peek(ctx)->type == TOK_COMMA)
@@ -657,6 +661,67 @@ static int parse_call_args(spl_comp_t *ctx) {
     return nargs;
 }
 
+/* Type check: warn when a value is passed where a pointer of the same type is expected.
+ * This catches bugs like passing `tok` (Token) where `*Token` is expected. */
+static void spl_check_arg_type(spl_comp_t *ctx, const char *fname, spl_type_info_t *arg_type,
+                               spl_type_info_t *param_type, int arg_idx) {
+    if (!arg_type || !param_type)
+        return;
+    if (param_type->kind == TYPE_PTR && param_type->elem && arg_type->kind != TYPE_PTR &&
+        arg_type->name && param_type->elem->name &&
+        strcmp(arg_type->name, param_type->elem->name) == 0) {
+        fprintf(stderr,
+                "%s: warning: argument %d of '%s' expects '%s*', "
+                "got '%s' (missing '&'?)\n",
+                ctx->fname, arg_idx + 1, fname, param_type->elem->name, arg_type->name);
+    }
+}
+
+/* Wrapper: parse_call_args with type checking against parameter types */
+static int parse_call_args_checked(spl_comp_t *ctx, const char *fname,
+                                   spl_type_info_t **param_types, int nparams) {
+    int nargs = 0;    /* physical slot count (for CALL) */
+    int nlogical = 0; /* logical arg index (for param_types lookup) */
+    if (peek(ctx)->type != TOK_R_PAREN) {
+        for (;;) {
+            spl_expr_result_t arg = spl_parse_expr(ctx, PREC_MIN);
+            if (param_types && nlogical < nparams && param_types[nlogical])
+                spl_check_arg_type(ctx, fname, arg.type, param_types[nlogical], nlogical);
+
+            /* For multi-slot struct/enum by-value parameters, expand
+             * the address left on the stack into multiple data slots. */
+            int arg_slots = 1;
+            if (param_types && nlogical < nparams && param_types[nlogical] && arg.type &&
+                param_types[nlogical]->kind != TYPE_PTR &&
+                !spl_type_is_scalar(param_types[nlogical]) &&
+                spl_type_size(param_types[nlogical]) > sizeof(spl_val_t)) {
+                usize nslots = (spl_type_size(param_types[nlogical]) + sizeof(spl_val_t) - 1) /
+                               sizeof(spl_val_t);
+                for (usize i = 0; i < nslots; i++) {
+                    spl_emit(ctx, SPL_DUP, SPL_VOID, 0);
+                    if (i > 0) {
+                        spl_emit(ctx, SPL_PUSH, SPL_USIZE, i * sizeof(spl_val_t));
+                        spl_emit(ctx, SPL_ADD, SPL_USIZE, 0);
+                    }
+                    spl_emit(ctx, SPL_LOAD, SPL_PTR, 0);
+                    spl_emit(ctx, SPL_SWAP, SPL_VOID, 0);
+                }
+                spl_emit(ctx, SPL_DROP, SPL_VOID, 0);
+                arg_slots = (int)nslots;
+            }
+
+            nargs += arg_slots;
+            nlogical++;
+            if (peek(ctx)->type == TOK_COMMA) {
+                advance(ctx);
+                continue;
+            }
+            break;
+        }
+    }
+    return nargs;
+}
+
 static spl_expr_result_t parse_ident(spl_comp_t *ctx) {
     spl_tok_t *t = advance(ctx);
     char name[256];
@@ -673,7 +738,7 @@ static spl_expr_result_t parse_ident(spl_comp_t *ctx) {
         spl_func_info_t *f = &vec_at(ctx->funcs, fi);
         advance(ctx); /* skip ( */
 
-        int nargs = parse_call_args(ctx);
+        int nargs = parse_call_args_checked(ctx, f->name, f->param_types, f->nparams);
         expect(ctx, TOK_R_PAREN);
 
         if (f->is_extern) {
@@ -690,6 +755,23 @@ static spl_expr_result_t parse_ident(spl_comp_t *ctx) {
         }
 
         spl_expr_result_t r = {f->ret_type, 0};
+
+        /* Multi-slot struct return: copy from returned address to caller's
+         * temp space. The returned address points to fp[1] in callee's frame
+         * (fp[0] is a gap). After RET, sp = callee_fp, so the first PUSH in
+         * emit_copy_slots (DUP) writes to the gap slot, not data. */
+        if (f->ret_type && !spl_type_is_scalar(f->ret_type) &&
+            spl_type_size(f->ret_type) > sizeof(spl_val_t)) {
+            usize nslots = spl_type_slot_count(f->ret_type);
+            int temp_offset = ctx->current_local_bytes;
+            ctx->current_local_bytes += (int)(nslots * sizeof(spl_val_t));
+            if (ctx->current_local_bytes > ctx->peak_local_bytes)
+                ctx->peak_local_bytes = ctx->current_local_bytes;
+            spl_emit_copy_slots(ctx, temp_offset, nslots);
+            spl_emit(ctx, SPL_LADDR, SPL_PTR, temp_offset);
+            r.is_lvalue = 1;
+        }
+
         return r;
     }
 
@@ -946,7 +1028,15 @@ static spl_expr_result_t parse_postfix_expr(spl_comp_t *ctx, spl_expr_result_t l
                             nargs = 0;
                         }
 
-                        nargs += parse_call_args(ctx);
+                        {
+                            spl_type_info_t **cp = func->param_types;
+                            int cn = func->nparams;
+                            if (is_instance && cn > 0) {
+                                cp++;
+                                cn--;
+                            }
+                            nargs += parse_call_args_checked(ctx, func->name, cp, cn);
+                        }
                         expect(ctx, TOK_R_PAREN);
 
                         /* Record fixup for forward-reference resolution */
@@ -957,6 +1047,20 @@ static spl_expr_result_t parse_postfix_expr(spl_comp_t *ctx, spl_expr_result_t l
                         vec_push(ctx->call_fixup_funcs, func->func_idx);
 
                         left = (spl_expr_result_t){func->ret_type, 0};
+
+                        /* Multi-slot return: copy to temp, keep address */
+                        if (func->ret_type && !spl_type_is_scalar(func->ret_type) &&
+                            spl_type_size(func->ret_type) > sizeof(spl_val_t)) {
+                            usize nslots = spl_type_slot_count(func->ret_type);
+                            int temp_offset = ctx->current_local_bytes;
+                            ctx->current_local_bytes += (int)(nslots * sizeof(spl_val_t));
+                            if (ctx->current_local_bytes > ctx->peak_local_bytes)
+                                ctx->peak_local_bytes = ctx->current_local_bytes;
+                            spl_emit_copy_slots(ctx, temp_offset, nslots);
+                            spl_emit(ctx, SPL_LADDR, SPL_PTR, temp_offset);
+                            left.is_lvalue = 1;
+                        }
+
                         break;
                     }
                 }
@@ -1193,7 +1297,10 @@ static spl_expr_result_t parse_infix(spl_comp_t *ctx, spl_expr_result_t left, sp
 
         if (left.is_lvalue) {
             spl_type_t bt = spl_type_emit_type(left.type);
-            if (op == TOK_ASSIGN) {
+            if (op == TOK_ASSIGN && left.type && !spl_type_is_scalar(left.type) &&
+                right.is_lvalue) {
+                spl_emit_copy_addr_to_addr(ctx, spl_type_slot_count(left.type), 0);
+            } else if (op == TOK_ASSIGN) {
                 spl_emit(ctx, SPL_STORE, bt, 0);
             } else {
                 spl_emit(ctx, SPL_PICK, SPL_VOID, 1);
@@ -1310,8 +1417,20 @@ void spl_emit_match_value_cmp(spl_comp_t *ctx, int val_offset) {
  * ============================================================ */
 
 void spl_emit_ret(spl_comp_t *ctx, spl_type_info_t *ret_type) {
-    spl_type_t rt = ret_type ? spl_type_emit_type(ret_type) : SPL_VOID;
-    spl_emit(ctx, SPL_RET, rt, 0);
+    if (ret_type && !spl_type_is_scalar(ret_type) && spl_type_size(ret_type) > sizeof(spl_val_t)) {
+        /* Multi-slot struct return: copy to fp[0..nslots-1] (above saved_sp),
+         * then return address of fp[0]. Caller copies from that address to its
+         * own temp space (see parse_ident / method call handling). */
+        usize nslots = spl_type_slot_count(ret_type);
+        /* Store at fp[1..nslots] (skip fp[0] as gap) so that RET's PUSH
+         * and caller's LADDR both write to the gap slot, not the data. */
+        spl_emit_copy_slots(ctx, (int)sizeof(spl_val_t), nslots);
+        spl_emit(ctx, SPL_LADDR, SPL_PTR, (int)sizeof(spl_val_t));
+        spl_emit(ctx, SPL_RET, SPL_PTR, 0);
+    } else {
+        spl_type_t rt = ret_type ? spl_type_emit_type(ret_type) : SPL_VOID;
+        spl_emit(ctx, SPL_RET, rt, 0);
+    }
 }
 
 /* ============================================================
@@ -1336,7 +1455,11 @@ void spl_emit_store_init(spl_comp_t *ctx, int var_offset, spl_type_info_t *var_t
         for (int i = (int)var_type->array_len - 1; i >= 0; i--) {
             spl_emit(ctx, SPL_LADDR, SPL_PTR, var_offset + (int)(i * stride));
             spl_emit(ctx, SPL_SWAP, SPL_VOID, 0);
-            spl_emit(ctx, SPL_STORE, bt, 0);
+            if (elem && !spl_type_is_scalar(elem)) {
+                spl_emit_copy_addr_to_addr(ctx, spl_type_slot_count(elem), 0);
+            } else {
+                spl_emit(ctx, SPL_STORE, bt, 0);
+            }
         }
     } else if (var_type && var_type->kind == TYPE_SLICE) {
         spl_emit(ctx, SPL_LADDR, SPL_PTR, var_offset + (int)sizeof(spl_val_t));
diff --git a/stage1/spl_parser.c b/stage1/spl_parser.c
index c653bdd..5e88e36 100644
--- a/stage1/spl_parser.c
+++ b/stage1/spl_parser.c
@@ -86,14 +86,49 @@ static int parse_fn_body(spl_comp_t *ctx, const char *fn_name, spl_type_info_t *
             skip_nl(ctx);
         }
 
-        spl_patch(ctx, alloc_addr, ctx->peak_local_bytes / (int)sizeof(spl_val_t) - nparams);
+        /* Compute physical param slot count (1 slot = 8 bytes).
+         * Multi-slot struct params occupy ceil(size/8) slots; scalar params occupy 1 each. */
+        int total_phys_slots = 0;
+        for (int i = 0; i < nparams; i++) {
+            usize psz = spl_type_size(ptypes[i]);
+            total_phys_slots += (int)((psz + sizeof(spl_val_t) - 1) / sizeof(spl_val_t));
+        }
+        /* Ensure ALLOC provides enough space for multi-slot return value
+         * pre-placed at fp[0..nslots-1] (above saved_sp). */
+        if (ret_type && !spl_type_is_scalar(ret_type) &&
+            spl_type_size(ret_type) > sizeof(spl_val_t)) {
+            usize min_bytes = spl_type_slot_count(ret_type) * sizeof(spl_val_t);
+            if ((usize)ctx->peak_local_bytes < min_bytes)
+                ctx->peak_local_bytes = (int)min_bytes;
+        }
+        spl_patch(ctx, alloc_addr,
+                  ctx->peak_local_bytes / (int)sizeof(spl_val_t) - total_phys_slots);
         expect(ctx, TOK_R_BRACE);
     }
 
     spl_emit_defer_epilogue(ctx, ctx->scope_depth);
     spl_pop_scope(ctx);
 
-    spl_emit(ctx, SPL_RET, SPL_VOID, 0);
+    /* Store param_types for call-site type checking and multi-slot expansion */
+    {
+        spl_func_info_t *f = &vec_at(ctx->funcs, fi);
+        f->param_types = calloc(nparams, sizeof(spl_type_info_t *));
+        f->param_names = calloc(nparams, sizeof(char *));
+        for (int i = 0; i < nparams; i++) {
+            f->param_types[i] = ptypes[i];
+            f->param_names[i] = strdup(pnames[i]);
+        }
+    }
+
+    /* Epilogue return: for multi-slot returns, return address of fp[1]
+     * (fp[0] is a gap slot that absorbs the RET PUSH, data at fp[1..nslots]). */
+    if (ctx->current_ret_type && !spl_type_is_scalar(ctx->current_ret_type) &&
+        spl_type_size(ctx->current_ret_type) > sizeof(spl_val_t)) {
+        spl_emit(ctx, SPL_LADDR, SPL_PTR, (int)sizeof(spl_val_t));
+        spl_emit(ctx, SPL_RET, SPL_PTR, 0);
+    } else {
+        spl_emit(ctx, SPL_RET, SPL_VOID, 0);
+    }
     spl_prog_end_func(&ctx->prog, fi);
     ctx->current_func_idx = -1;
     ctx->current_ret_type = NULL;
@@ -183,16 +218,6 @@ static void parse_method_decl(spl_comp_t *ctx, spl_type_info_t *container) {
 
     int fi = parse_fn_body(ctx, qualified, ret_type, nparams, pnames, ptypes, 0);
 
-    {
-        spl_func_info_t *f = &vec_at(ctx->funcs, fi);
-        f->param_types = calloc(nparams, sizeof(spl_type_info_t *));
-        f->param_names = calloc(nparams, sizeof(char *));
-        for (int i = 0; i < nparams; i++) {
-            f->param_types[i] = ptypes[i];
-            f->param_names[i] = strdup(pnames[i]);
-        }
-    }
-
     spl_type_add_method(container, mname, fi);
 }
 
diff --git a/stage1/spl_stmt.c b/stage1/spl_stmt.c
index 1b6c59e..e71eb21 100644
--- a/stage1/spl_stmt.c
+++ b/stage1/spl_stmt.c
@@ -451,11 +451,16 @@ static void parse_for_stmt(spl_comp_t *ctx) {
     spl_emit(ctx, SPL_PUSH, SPL_U64, elem_byte_size);
     spl_emit(ctx, SPL_MUL, SPL_U64, 0);
     spl_emit(ctx, SPL_ADD, SPL_U64, 0);
-    spl_type_t elem_bt = elem_type ? spl_type_emit_type(elem_type) : SPL_I32;
-    spl_emit(ctx, SPL_LOAD, elem_bt, 0);
-    spl_emit(ctx, SPL_LADDR, SPL_PTR, val_offset);
-    spl_emit(ctx, SPL_SWAP, SPL_VOID, 0);
-    spl_emit(ctx, SPL_STORE, elem_bt, 0);
+    if (elem_type && !spl_type_is_scalar(elem_type) &&
+        spl_type_size(elem_type) > sizeof(spl_val_t)) {
+        spl_emit_copy_slots(ctx, val_offset, spl_type_slot_count(elem_type));
+    } else {
+        spl_type_t elem_bt = elem_type ? spl_type_emit_type(elem_type) : SPL_I32;
+        spl_emit(ctx, SPL_LOAD, elem_bt, 0);
+        spl_emit(ctx, SPL_LADDR, SPL_PTR, val_offset);
+        spl_emit(ctx, SPL_SWAP, SPL_VOID, 0);
+        spl_emit(ctx, SPL_STORE, elem_bt, 0);
+    }
 
     skip_nl(ctx);
     spl_parse_block(ctx); /* body */
diff --git a/stage1/test10_struct.spl b/stage1/test10_struct.spl
index e266387..74c8392 100644
--- a/stage1/test10_struct.spl
+++ b/stage1/test10_struct.spl
@@ -8,6 +8,133 @@ type Pair = struct {
     b: i32,
 }
 
+type Three = struct {
+    a: i64,
+    b: i64,
+    c: i64,
+}
+
+type Tag = enum {
+    Unknown,
+    BlockComment,
+    LineComment,
+    Ident,
+    Number,
+}
+
+type Token = struct {
+    loc_start: i32,
+    loc_end: i32,
+    tag: Tag,
+}
+
+fn make_three(a: i64, b: i64, c: i64) Three {
+    ret Three { .a = a, .b = b, .c = c };
+}
+
+fn sum_three(t: Three) i64 {
+    ret t.a + t.b + t.c;
+}
+
+fn make_token(s: i32, e: i32, t: Tag) Token {
+    ret Token { .loc_start = s, .loc_end = e, .tag = t };
+}
+
+fn test_ret_enum_struct() i32 {
+    var tok := make_token(10, 20, Tag.BlockComment);
+    if tok.loc_start != 10 { ret 1; }
+    if tok.loc_end != 20 { ret 2; }
+    if tok.tag != Tag.BlockComment { ret 3; }
+    ret 0;
+}
+
+fn test_nested_ret_enum() i32 {
+    var tok := make_token(1, 5, Tag.Ident);
+    if tok.tag != Tag.Ident { ret 1; }
+    var tok2 := make_token(6, 9, Tag.Number);
+    if tok2.tag != Tag.Number { ret 2; }
+    if tok.tag != Tag.Ident { ret 3; }
+    ret 0;
+}
+
+fn test_copy_token() i32 {
+    var tok := make_token(0, 100, Tag.LineComment);
+    var c := tok;
+    if c.loc_start != 0 { ret 1; }
+    if c.tag != Tag.LineComment { ret 2; }
+    c.tag = Tag.Ident;
+    if tok.tag != Tag.LineComment { ret 3; }
+    if c.tag != Tag.Ident { ret 4; }
+    ret 0;
+}
+
+fn test_pass_token(t: Token) i32 {
+    if t.tag != Tag.Number { ret 1; }
+    if t.loc_start != 42 { ret 2; }
+    ret 0;
+}
+
+fn test_param_pass_token() i32 {
+    var tok := make_token(42, 99, Tag.Number);
+    var r := test_pass_token(tok);
+    if r != 0 { ret r; }
+    ret 0;
+}
+
+fn test_get_tag(tok: Token) i32 {
+    ret tok.tag;
+}
+
+fn test_chain_func_call() i32 {
+    var tok := make_token(1, 2, Tag.BlockComment);
+    var tg := test_get_tag(tok);
+    if tg != Tag.BlockComment { ret 1; }
+    var tok2 := make_token(3, 4, Tag.LineComment);
+    var tg2 := test_get_tag(tok2);
+    if tg2 != Tag.LineComment { ret 2; }
+    ret 0;
+}
+
+fn test_ret_multi_slot_struct() i32 {
+    var t := make_three(10, 20, 30);
+    if t.a != 10 { ret 1; }
+    if t.b != 20 { ret 2; }
+    if t.c != 30 { ret 3; }
+    ret 0;
+}
+
+fn test_pass_struct_by_value() i32 {
+    var t := make_three(10, 20, 30);
+    var sum := sum_three(t);
+    if sum != 60 { ret 1; }
+    ret 0;
+}
+
+fn test_copy_struct() i32 {
+    var t := make_three(10, 20, 30);
+    var t2: Three;
+    t2 = t;
+    if t2.a != 10 { ret 1; }
+    t2.a = 99;
+    if t.a != 10 { ret 2; }
+    if t2.a != 99 { ret 3; }
+    ret 0;
+}
+
+fn test_multi_calls() i32 {
+    var ta := make_three(5, 10, 15);
+    var tb := make_three(20, 25, 30);
+    if ta.a + ta.b + ta.c != 30 { ret 1; }
+    if tb.a + tb.b + tb.c != 75 { ret 2; }
+    ret 0;
+}
+
+fn test_literal_arg() i32 {
+    var sum := sum_three(Three { .a = 7, .b = 8, .c = 9 });
+    if sum != 24 { ret 1; }
+    ret 0;
+}
+
 fn main() i32 {
     /* struct 字段访问 */
     var p: Pair;
@@ -60,5 +187,29 @@ fn main() i32 {
     if o.inner.val != 42 { ret 7; }
     if o.extra != 58 { ret 8; }
 
+    /* 多 slot 结构体返回值测试 */
+    var r9 := test_ret_multi_slot_struct();
+    if r9 != 0 { ret 100; }
+    var r10 := test_pass_struct_by_value();
+    if r10 != 0 { ret 101; }
+    var r11 := test_copy_struct();
+    if r11 != 0 { ret 102; }
+    var r12 := test_multi_calls();
+    if r12 != 0 { ret 103; }
+    var r13 := test_literal_arg();
+    if r13 != 0 { ret 104; }
+
+    /* 含 enum 字段的结构体返回值测试 */
+    var r14 := test_ret_enum_struct();
+    if r14 != 0 { ret 110; }
+    var r15 := test_nested_ret_enum();
+    if r15 != 0 { ret 111; }
+    var r16 := test_copy_token();
+    if r16 != 0 { ret 112; }
+    var r17 := test_param_pass_token();
+    if r17 != 0 { ret 113; }
+    var r18 := test_chain_func_call();
+    if r18 != 0 { ret 114; }
+
     ret 0;
 }