#include "spl_sema.h"
#include "spl_intrin.h"
#include "spl_type.h"

void spl_scope_init(spl_scope_t *scope) {
    vec_init(scope->scopes);
    vec_push(scope->scopes, (spl_scope_node_t){0});
    scope->current_scope = 0;
    scope->root_scope = 0;
}

void spl_scope_drop(spl_scope_t *scope) {
    for (usize i = 0; i < vec_size(scope->scopes); ++i) {
        map_free(vec_at(scope->scopes, i).symbols);
    }
    vec_free(scope->scopes);
    scope->current_scope = 0;
    scope->root_scope = 0;
}

spl_scope_id_t spl_scope_alloc(spl_scope_t *scope) {
    spl_scope_node_t n = {0};
    n.parent = scope->current_scope;
    map_init(n.symbols, MAP_HASH_STR, MAP_CMP_STR);
    vec_push(scope->scopes, n);
    return vec_size(scope->scopes) - 1;
}

bool spl_scope_insert(spl_scope_t *scope, spl_scope_id_t id, spl_symbol_t symbol) {
    if (!id || id >= vec_size(scope->scopes)) {
        LOG_FATAL("sema scope insert error");
        return false;
    }
    spl_scope_node_t *node = &vec_at(scope->scopes, id);
    spl_symbol_t old = {0};
    if (map_get(node->symbols, symbol.name, &old)) {
        SPL_ERROR(&(spl_dbg_node_t){0}, "duplicate symbol `%s`", symbol.name);
        return false;
    }
    map_put(node->symbols, symbol.name, symbol);
    return true;
}

bool spl_scope_find(spl_scope_t *scope, const char *name, spl_symbol_t *out) {
    if (!scope || !name || !out)
        return false;
    for (spl_scope_id_t id = scope->current_scope; id != 0; id = vec_at(scope->scopes, id).parent) {
        spl_scope_node_t *s = &vec_at(scope->scopes, id);
        if (map_get(s->symbols, name, out)) {
            return true;
        }
    }
    return false;
}

static spl_ast_node_ref_vec_t *node_attr_list(spl_ast_node_t *n) {
    switch (n->kind) {
    case SPL_AST_FN_DECL:
        return &n->fn_decl.tag_list;
    case SPL_AST_VAR_DECL:
    case SPL_AST_CONST_DECL:
        return &n->var_const_decl.attr_list;
    case SPL_AST_TYPE_DECL:
        return &n->type_decl.attr_list;
    case SPL_AST_PARAM_DECL:
        return &n->param_decl.attr_list;
    case SPL_AST_MEMBER_DECL:
        return &n->member_decl.attr_list;
    case SPL_AST_TOP_LEVEL_BLOCK:
        return &n->top_level_block.tag_list;
    default:
        return NULL;
    }
}

static void sema_resolve_attrs(spl_sema_t *sema, spl_ast_node_ref_vec_t *raw,
                               spl_attr_id_vec_t *out) {
    for (usize i = 0; i < vec_size(*raw); ++i) {
        spl_ast_node_ref_t aref = vec_at(*raw, i);
        spl_ast_node_t *a = spl_ast_node(sema->ast, aref);
        if (!a || (a->kind != SPL_AST_TAG_ITEM && a->kind != SPL_AST_EXTERNAL_TAG_ITEM))
            continue;

        spl_attr_info_t *info = spl_attr_lookup(sema->attr, NULL, a->tag_item.name);
        if (!info) {
            SPL_ERROR(&a->dbg, "unknown attribute `%s`", a->tag_item.name);
            sema->error_count++;
            continue;
        }

        usize nargs = vec_size(a->tag_item.args);
        if ((int)nargs < info->min_args || (info->max_args >= 0 && (int)nargs > info->max_args)) {
            SPL_ERROR(&a->dbg, "attribute `%s` expects %d..%d args, got %zu", info->name,
                      info->min_args, info->max_args, nargs);
            sema->error_count++;
            continue;
        }

        spl_attr_arg_vec_t args;
        vec_init(args);
        int bad = 0;
        for (usize j = 0; j < nargs; ++j) {
            spl_ast_node_t *arg = spl_ast_node(sema->ast, vec_at(a->tag_item.args, j));
            spl_attr_arg_t oa = {0};
            if (!arg) {
                bad = 1;
                break;
            }
            switch (arg->kind) {
            case SPL_AST_EXPR_IDENT:
                oa.kind = SPL_ATTR_ARG_STR;
                oa.value.s = arg->ident.name;
                break;
            case SPL_AST_EXPR_STRING_LIT:
                oa.kind = SPL_ATTR_ARG_STR;
                oa.value.s = arg->string_lit.data;
                break;
            case SPL_AST_EXPR_INT_LIT:
                oa.kind = SPL_ATTR_ARG_INT;
                oa.value.i = arg->int_lit.bits;
                break;
            default:
                SPL_ERROR(&a->dbg, "attribute arg #%zu has unsupported form", j);
                sema->error_count++;
                bad = 1;
                break;
            }
            if (bad)
                break;
            vec_push(args, oa);
        }
        if (bad) {
            vec_free(args);
            continue;
        }

        spl_attr_id_t id = spl_attr_alloc(sema->attr, info, args);
        vec_push(*out, id);
    }
}

static spl_lang_type_id_t sema_infer(spl_sema_t *sema, spl_ast_node_ref_t ref);
static spl_lang_type_id_t sema_coerce(spl_sema_t *sema, spl_ast_node_ref_t ref,
                                      spl_lang_type_id_t expected);
static spl_lang_type_id_t sema_intrin_call(spl_sema_t *sema, spl_ast_node_t *n, spl_intrin_t in,
                                           spl_ast_node_ref_vec_t *args);
static spl_lang_type_id_t sema_intrin_field(spl_sema_t *sema, spl_ast_node_t *n, spl_intrin_t in);
static spl_lang_type_id_t sema_eval_decl(spl_sema_t *sema, spl_def_id_t def_id);
static spl_lang_type_id_t sema_infer_fn_signature(spl_sema_t *sema, spl_ast_node_t *n);

static bool sema_is_infer(spl_sema_t *sema, spl_lang_type_id_t tid) {
    spl_lang_type_node_t *n = spl_lang_type_node(sema->type, tid);
    return n && n->kind == SPL_LANG_TYPE_INFER;
}

static spl_lang_type_id_t sema_lang_from_ir(spl_sema_t *sema, spl_type_id_t ir) {
    for (usize i = 1; i < vec_size(sema->type->lang_table); ++i) {
        spl_lang_type_node_t *ln = &vec_at(sema->type->lang_table, i);
        if (ln->ir_type_id == ir)
            return i;
    }
    return 0;
}

static bool sema_is_literal(spl_ast_node_t *n) {
    switch (n->kind) {
    case SPL_AST_EXPR_INT_LIT:
    case SPL_AST_EXPR_FLOAT_LIT:
    case SPL_AST_EXPR_CHAR_LIT:
    case SPL_AST_EXPR_STRING_LIT:
    case SPL_AST_EXPR_BOOL_LIT:
    case SPL_AST_EXPR_NULL_LIT:
    case SPL_AST_EXPR_UNDEFINED_LIT:
        return true;
    default:
        return false;
    }
}

static void sema_type_to_str(spl_sema_t *sema, spl_lang_type_id_t tid, char *buf, usize cap) {
    if (!buf || cap == 0)
        return;
    if (tid == 0) {
        snprintf(buf, cap, "<none>");
        return;
    }
    spl_lang_type_node_t *n = spl_lang_type_node(sema->type, tid);
    if (!n) {
        snprintf(buf, cap, "<invalid lang#%zu>", tid);
        return;
    }
    spl_type_node_t *ir = spl_type_node(sema->type, n->ir_type_id);
    switch (n->kind) {
    case SPL_LANG_TYPE_INT:
        if (ir && ir->int_type.bits == 0)
            snprintf(buf, cap, "comptime_int(#%zu)", tid);
        else if (ir)
            snprintf(buf, cap, "%s%zu(#%zu)", ir->int_type.is_signed ? "i" : "u", ir->int_type.bits,
                     tid);
        else
            snprintf(buf, cap, "int?(#%zu)", tid);
        break;
    case SPL_LANG_TYPE_FLOAT:
        if (ir && ir->float_type.bits == 0)
            snprintf(buf, cap, "comptime_float(#%zu)", tid);
        else if (ir)
            snprintf(buf, cap, "f%zu(#%zu)", ir->float_type.bits, tid);
        else
            snprintf(buf, cap, "float?(#%zu)", tid);
        break;
    case SPL_LANG_TYPE_BOOL:
        snprintf(buf, cap, "bool(#%zu)", tid);
        break;
    case SPL_LANG_TYPE_UNIT:
        snprintf(buf, cap, "unit(#%zu)", tid);
        break;
    case SPL_LANG_TYPE_NEVER:
        snprintf(buf, cap, "never(#%zu)", tid);
        break;
    case SPL_LANG_TYPE_ANY:
        snprintf(buf, cap, "any(#%zu)", tid);
        break;
    case SPL_LANG_TYPE_INFER:
        snprintf(buf, cap, "infer(#%zu)", tid);
        break;
    case SPL_LANG_TYPE_ERROR:
        snprintf(buf, cap, "error(#%zu)", tid);
        break;
    case SPL_LANG_TYPE_PTR:
        snprintf(buf, cap, "ptr(#%zu)", tid);
        break;
    case SPL_LANG_TYPE_ARRAY:
        snprintf(buf, cap, "array(#%zu)", tid);
        break;
    case SPL_LANG_TYPE_SLICE:
        snprintf(buf, cap, "slice(#%zu)", tid);
        break;
    case SPL_LANG_TYPE_TUPLE:
        snprintf(buf, cap, "tuple(#%zu)", tid);
        break;
    case SPL_LANG_TYPE_RANGE:
        snprintf(buf, cap, "range(#%zu)", tid);
        break;
    case SPL_LANG_TYPE_FN:
        snprintf(buf, cap, "fn(#%zu)", tid);
        break;
    case SPL_LANG_TYPE_VARARGS:
        snprintf(buf, cap, "varargs(#%zu)", tid);
        break;
    default:
        snprintf(buf, cap, "langkind=%d ir=%zu(#%zu)", (int)n->kind, n->ir_type_id, tid);
        break;
    }
}

static inline void sema_push_scope(spl_sema_t *sema) {
    spl_scope_id_t new_scope = spl_scope_alloc(sema->scope);
    sema->store_scope = sema->scope->current_scope;
    sema->scope->current_scope = new_scope;
}

static inline void sema_pop_scope(spl_sema_t *sema) {
    spl_scope_id_t cur = sema->scope->current_scope;
    if (cur != 0 && cur < vec_size(sema->scope->scopes)) {
        sema->scope->current_scope = vec_at(sema->scope->scopes, cur).parent;
    } else {
        sema->scope->current_scope = sema->store_scope;
    }
}

static spl_lang_type_id_t sema_for_elem_type(spl_sema_t *sema, spl_lang_type_id_t lang_tid) {
    spl_lang_type_node_t *n = spl_lang_type_node(sema->type, lang_tid);
    if (!n)
        return 0;
    switch (n->kind) {
    case SPL_LANG_TYPE_ARRAY:
    case SPL_LANG_TYPE_SLICE:
    case SPL_LANG_TYPE_RANGE:
    case SPL_LANG_TYPE_PTR:
        return n->extra.elem;
    default:
        return 0;
    }
}

static spl_lang_type_id_t sema_infer_fn_signature(spl_sema_t *sema, spl_ast_node_t *n) {
    if (!n || n->resolved_def_id == 0)
        return 0;
    spl_def_node_t *def = spl_def_node(sema->type, n->resolved_def_id);
    if (def && def->lang_id != 0)
        return def->lang_id;

    spl_lang_type_id_vec_t param_types;
    vec_init(param_types);
    for (usize i = 0; i < vec_size(n->fn_decl.params); ++i) {
        spl_ast_node_t *pd = spl_ast_node(sema->ast, vec_at(n->fn_decl.params, i));
        if (pd && pd->kind == SPL_AST_PARAM_DECL && pd->param_decl.type_expr)
            vec_push(param_types, sema_infer(sema, pd->param_decl.type_expr));
        else
            vec_push(param_types, spl_lang_make_varargs(sema->type));
    }
    spl_lang_type_id_t ret_tid = sema_infer(sema, n->fn_decl.ret_type);
    if (ret_tid == 0)
        ret_tid = spl_lang_make_unit(sema->type);
    spl_lang_type_id_t fn_tid = spl_lang_make_fn(
        sema->type, ret_tid, vec_unsafe_get_data(param_types), vec_size(param_types));
    vec_free(param_types);
    spl_def_resolve(sema->type, n->resolved_def_id, fn_tid);
    return fn_tid;
}

static spl_lang_type_id_t sema_build_aggregate(spl_sema_t *sema, spl_ast_node_t *te,
                                               spl_def_id_t owner_def_id) {
    spl_type_member_vec_t members;
    vec_init(members);
    spl_lang_method_vec_t methods;
    vec_init(methods);

    for (usize i = 0; i < vec_size(te->type_aggregate.members); ++i) {
        spl_ast_node_ref_t mref = vec_at(te->type_aggregate.members, i);
        spl_ast_node_t *mn = spl_ast_node(sema->ast, mref);
        if (!mn)
            continue;

        if (mn->kind == SPL_AST_MEMBER_DECL) {
            spl_lang_type_id_t mtid = sema_infer(sema, mn->member_decl.type_expr);
            spl_type_member_t m = {.name = mn->member_decl.name,
                                   .type_id = spl_lang_type_get_ir_type(sema->type, mtid),
                                   .ast_node_ref = mref};
            vec_push(members, m);
        } else if (mn->kind == SPL_AST_FN_DECL) {
            spl_def_id_t fn_def =
                spl_def_alloc(sema->type, SPL_DEF_FN, mn->fn_decl.name, mn->dbg, mref);
            mn->resolved_def_id = fn_def;
            spl_def_node_t *fn_d = spl_def_node(sema->type, fn_def);
            if (fn_d)
                fn_d->owner_def = owner_def_id;
            spl_lang_method_t meth = {.name = mn->fn_decl.name, .def_id = fn_def};
            vec_push(methods, meth);
        }
    }

    spl_type_node_kind_t tk;
    if (strcmp(te->type_aggregate.kind_name, "struct") == 0)
        tk = SPL_TYPE_STRUCT;
    else if (strcmp(te->type_aggregate.kind_name, "union") == 0)
        tk = SPL_TYPE_UNION;
    else if (strcmp(te->type_aggregate.kind_name, "enum") == 0)
        tk = SPL_TYPE_ENUM;
    else
        tk = SPL_TYPE_STRUCT;

    spl_type_layout_t layout = {.mode = SPL_TYPE_LAYOUT_AUTO};
    spl_type_id_t agg_ir = spl_type_builder_agg(sema->type, tk, &members,
                                                spl_type_builder_int(sema->type, 32, 1), layout);
    vec_free(members);

    spl_lang_type_kind_t lk;
    switch (tk) {
    case SPL_TYPE_STRUCT:
        lk = SPL_LANG_TYPE_STRUCT;
        break;
    case SPL_TYPE_UNION:
        lk = SPL_LANG_TYPE_UNION;
        break;
    case SPL_TYPE_ENUM:
        lk = SPL_LANG_TYPE_ENUM;
        break;
    case SPL_TYPE_SHAPE:
        lk = SPL_LANG_TYPE_SHAPE;
        break;
    default:
        lk = SPL_LANG_TYPE_STRUCT;
        break;
    }
    spl_lang_type_node_t ln = {0};
    ln.kind = lk;
    ln.ir_type_id = agg_ir;
    ln.methods = methods;
    return spl_lang_node_push(sema->type, &ln);
}

static spl_lang_type_id_t sema_eval_decl(spl_sema_t *sema, spl_def_id_t def_id) {
    spl_def_node_t *def = spl_def_node(sema->type, def_id);
    if (!def)
        return 0;

    if (def->state == SPL_DECL_RESOLVED || def->state == SPL_DECL_ERROR)
        return def->lang_id;

    if (def->lang_id != 0) {
        def->state = SPL_DECL_RESOLVED;
        return def->lang_id;
    }

    if (def->state == SPL_DECL_RESOLVING) {
        SPL_ERROR(&def->dbg_node, "circular dependency on `%s`", def->name ? def->name : "?");
        sema->error_count++;
        def->state = SPL_DECL_ERROR;
        return 0;
    }

    def->state = SPL_DECL_RESOLVING;

    spl_ast_node_t *n = spl_ast_node(sema->ast, def->ast_node_ref);
    spl_lang_type_id_t result = 0;

    if (n) {
        switch (n->kind) {
        case SPL_AST_TYPE_DECL: {
            if (n->type_decl.type_expr) {
                spl_ast_node_t *te = spl_ast_node(sema->ast, n->type_decl.type_expr);
                if (te && te->kind == SPL_AST_TYPE_AGGREGATE)
                    result = sema_build_aggregate(sema, te, def_id);
                else
                    result = sema_infer(sema, n->type_decl.type_expr);
            }
            n->resolved_lang_tid = result;
            break;
        }
        case SPL_AST_FN_DECL: {
            spl_lang_type_id_t saved_agg = sema->current_aggregate_lang;
            if (def->owner_def) {
                spl_def_node_t *owner = spl_def_node(sema->type, def->owner_def);
                if (owner && owner->lang_id != 0)
                    sema->current_aggregate_lang = owner->lang_id;
            }
            result = sema_infer_fn_signature(sema, n);
            sema->current_aggregate_lang = saved_agg;
            break;
        }
        case SPL_AST_VAR_DECL:
        case SPL_AST_CONST_DECL: {
            if (n->var_const_decl.type)
                result = sema_infer(sema, n->var_const_decl.type);
            else if (n->var_const_decl.init_expr)
                result = sema_infer(sema, n->var_const_decl.init_expr);
            break;
        }
        default:
            break;
        }
    }

    spl_def_node_t *final_def = spl_def_node(sema->type, def_id);
    if (final_def) {
        final_def->lang_id = result;
        final_def->state = result ? SPL_DECL_RESOLVED : SPL_DECL_ERROR;
    }
    return result;
}

static void sema_collect_names(spl_sema_t *sema, spl_ast_node_ref_t ref) {
    spl_ast_node_t *n = spl_ast_node(sema->ast, ref);
    if (!n)
        return;

    switch (n->kind) {
    case SPL_AST_CONTAINER_MEMBERS: {
        /* root_scope 只在第一次创建，后续 module 复用 */
        if (sema->scope->root_scope == 0) {
            spl_scope_id_t root = spl_scope_alloc(sema->scope);
            sema->scope->root_scope = root;
        }

        /* 进入 root_scope，再为当前 module 开一个子 scope */
        sema->scope->current_scope = sema->scope->root_scope;
        spl_scope_id_t mod_scope = spl_scope_alloc(sema->scope);
        sema->scope->current_scope = mod_scope;

        spl_symbol_t file_sym = {.name = "$file", .kind = SPL_SYMBOL_KIND_TYPE};
        file_sym.node = spl_def_alloc(sema->type, SPL_DEF_AGG, "$file", n->dbg, ref);
        n->resolved_def_id = file_sym.node;
        spl_scope_insert(sema->scope, mod_scope, file_sym);

        for (usize i = 0; i < vec_size(n->container_members.declarations); ++i) {
            sema_collect_names(sema, vec_at(n->container_members.declarations, i));
        }

        /* 故意不恢复 current_scope
           保持 mod_scope 交给随后的 sema_parse 使用。
           恢复由 spl_sema_run_module 统一负责 */
        break;
    }
    case SPL_AST_TYPE_DECL: {
        spl_symbol_t sym = {.name = n->type_decl.name, .kind = SPL_SYMBOL_KIND_TYPE};
        spl_ast_node_t *te = spl_ast_node(sema->ast, n->type_decl.type_expr);
        if (!te) {
            SPL_ERROR(&n->dbg, "type declaration `%s` missing type expression", n->type_decl.name);
            sema->error_count++;
            return;
        }
        if (te->kind == SPL_AST_TYPE_AGGREGATE)
            sym.node = spl_def_alloc(sema->type, SPL_DEF_AGG, sym.name, te->dbg, ref);
        else
            sym.node = spl_def_alloc(sema->type, SPL_DEF_SCALAR, sym.name, te->dbg, ref);
        n->resolved_def_id = sym.node;
        spl_scope_insert(sema->scope, sema->scope->current_scope, sym);
        break;
    }
    case SPL_AST_FN_DECL: {
        spl_symbol_t sym = {.name = n->fn_decl.name, .kind = SPL_SYMBOL_KIND_FN};
        sym.node = spl_def_alloc(sema->type, SPL_DEF_FN, sym.name, n->dbg, ref);
        n->resolved_def_id = sym.node;
        spl_scope_insert(sema->scope, sema->scope->current_scope, sym);
        break;
    }
    case SPL_AST_VAR_DECL:
    case SPL_AST_CONST_DECL: {
        spl_ast_node_t *pat = spl_ast_node(sema->ast, n->var_const_decl.pattern);
        if (pat && pat->kind == SPL_AST_PATTERN_IDENT) {
            const char *name = pat->pattern_ident.name;
            spl_symbol_t sym = {.name = name, .kind = SPL_SYMBOL_KIND_VAR};
            sym.node = spl_def_alloc(sema->type, SPL_DEF_VAR, name, n->dbg, ref);
            n->resolved_def_id = sym.node;
            spl_scope_insert(sema->scope, sema->scope->current_scope, sym);
        } else {
            SPL_ERROR(&n->dbg, "unsupported variable pattern (only simple identifier)");
            sema->error_count++;
        }
        break;
    }
    case SPL_AST_TOP_LEVEL_BLOCK:
        if (n->top_level_block.block) {
            sema_collect_names(sema, n->top_level_block.block);
        }
        break;
    default:
        break;
    }
}

static void sema_collect_types(spl_sema_t *sema, spl_ast_node_ref_t ref) {
    spl_ast_node_t *n = spl_ast_node(sema->ast, ref);
    if (!n)
        return;
    switch (n->kind) {
    case SPL_AST_CONTAINER_MEMBERS:
        for (usize i = 0; i < vec_size(n->container_members.declarations); ++i) {
            spl_ast_node_ref_t dref = vec_at(n->container_members.declarations, i);
            spl_ast_node_t *d = spl_ast_node(sema->ast, dref);
            if (d && d->kind == SPL_AST_TYPE_DECL && d->resolved_def_id)
                sema_eval_decl(sema, d->resolved_def_id);
        }
        break;
    case SPL_AST_TOP_LEVEL_BLOCK:
        if (n->top_level_block.block)
            sema_collect_types(sema, n->top_level_block.block);
        break;
    default:
        break;
    }
}

static void sema_collect_signatures(spl_sema_t *sema) {
    usize n = vec_size(sema->type->def_table);
    for (usize i = 1; i < n; ++i) {
        spl_def_node_t *d = &vec_at(sema->type->def_table, i);
        if (d->kind == SPL_DEF_FN && d->state == SPL_DECL_UNRESOLVED)
            sema_eval_decl(sema, i);
    }
}

static void sema_collect(spl_sema_t *sema, spl_ast_node_ref_t ref) {
    sema_collect_names(sema, ref);
    sema_collect_types(sema, ref);
    sema_collect_signatures(sema);
}

static spl_lang_type_id_t sema_intrin_call(spl_sema_t *sema, spl_ast_node_t *n, spl_intrin_t in,
                                           spl_ast_node_ref_vec_t *args) {
    const spl_intrin_info_t *info = spl_intrin_info(in);
    usize nargs = vec_size(*args);
    if ((int)nargs < info->min_args || (info->max_args >= 0 && (int)nargs > info->max_args)) {
        SPL_ERROR(&n->dbg, "`%s` expects %d..%d args, got %zu", info->name, info->min_args,
                  info->max_args, nargs);
        sema->error_count++;
        return 0;
    }

    switch (in) {
    case SPL_INTRIN_SIZEOF:
    case SPL_INTRIN_ALIGNOF: {
        sema_infer(sema, vec_at(*args, 0));
        return spl_lang_make_int(sema->type, sizeof(void *) * 8, 0);
    }
    case SPL_INTRIN_ASSERT: {
        spl_lang_type_id_t bt = spl_lang_make_bool(sema->type);
        sema_coerce(sema, vec_at(*args, 0), bt);
        if (nargs == 2)
            sema_infer(sema, vec_at(*args, 1));
        return spl_lang_make_unit(sema->type);
    }
    case SPL_INTRIN_INT_CAST:
    case SPL_INTRIN_TRUNCATE:
    case SPL_INTRIN_BIT_CAST:
    case SPL_INTRIN_FLOAT_CAST:
    case SPL_INTRIN_INT_FROM_FLOAT:
    case SPL_INTRIN_FLOAT_FROM_INT:
    case SPL_INTRIN_PTR_FROM_INT:
    case SPL_INTRIN_PTR_CAST: {
        /* 双参数形式：源表达式 + 目标类型 */
        spl_lang_type_id_t src_lang = sema_infer(sema, vec_at(*args, 0));
        if (!src_lang)
            return 0;
        spl_lang_type_id_t dst_lang = sema_infer(sema, vec_at(*args, 1));
        if (!dst_lang)
            return 0;
        spl_type_id_t ft = spl_lang_type_get_ir_type(sema->type, src_lang);
        spl_type_id_t tt = spl_lang_type_get_ir_type(sema->type, dst_lang);
        spl_intrin_t expected = spl_intrin_lookup_cast(sema->type, ft, tt);
        if (expected == SPL_INTRIN_NONE) {
            SPL_ERROR(&n->dbg, "`%s`: incompatible types", info->name);
            sema->error_count++;
            return 0;
        }
        /* 允许显式 builtin 覆盖 as 的默认选择（例如用 @int_cast 代替 @truncate） */
        n->resolved_lang_tid = dst_lang;
        return dst_lang;
    }
    case SPL_INTRIN_INT_FROM_BOOL:
    case SPL_INTRIN_INT_FROM_PTR: {
        /* 单参数：目标类型默认 usize；双参数时以第二参数为准 */
        sema_infer(sema, vec_at(*args, 0));
        if (nargs >= 2) {
            spl_lang_type_id_t dst = sema_infer(sema, vec_at(*args, 1));
            if (!dst)
                return 0;
            n->resolved_lang_tid = dst;
            return dst;
        }
        spl_lang_type_id_t r = spl_lang_make_int(sema->type, sizeof(void *) * 8, 0);
        n->resolved_lang_tid = r;
        return r;
    }
    default:
        UNREACHABLE();
    }
    return 0;
}

static spl_lang_type_id_t sema_intrin_field(spl_sema_t *sema, spl_ast_node_t *n, spl_intrin_t in) {
    const spl_intrin_info_t *info = spl_intrin_info(in);
    switch (info->result) {
    case SPL_INTRIN_RESULT_USIZE:
        return spl_lang_make_int(sema->type, sizeof(void *) * 8, 0);
    case SPL_INTRIN_RESULT_BOOL:
        return spl_lang_make_bool(sema->type);
    case SPL_INTRIN_RESULT_UNIT:
        return spl_lang_make_unit(sema->type);
    default:
        UNREACHABLE();
    }
    (void)n;
    return 0;
}

static spl_lang_type_id_t sema_coerce(spl_sema_t *sema, spl_ast_node_ref_t ref,
                                      spl_lang_type_id_t expected) {
    if (!ref || !expected)
        return 0;
    spl_ast_node_t *n = spl_ast_node(sema->ast, ref);
    if (!n)
        return 0;

    spl_lang_type_id_t already = n->resolved_lang_tid;
    if (already == expected)
        return expected;

    /* 已定型 */
    if (already != 0) {
        spl_lang_type_node_t *an = spl_lang_type_node(sema->type, already);
        spl_type_node_t *air = an ? spl_type_node(sema->type, an->ir_type_id) : NULL;
        /* comptime 与 infer 都属于"可重定型"：清空 resolved 后按 expected 重新推导 */
        bool a_rebindable =
            (an && an->kind == SPL_LANG_TYPE_INFER) ||
            (an && an->kind == SPL_LANG_TYPE_INT && air && air->int_type.bits == 0) ||
            (an && an->kind == SPL_LANG_TYPE_FLOAT && air && air->float_type.bits == 0);
        if (!a_rebindable) {
            /* 具体类型：只接受子类型方向 */
            if (spl_lang_type_is_subtype(sema->type, already, expected)) {
                n->expected_lang_tid = expected;
                return expected;
            }
            char ebuf[128], gbuf[128];
            sema_type_to_str(sema, expected, ebuf, sizeof(ebuf));
            sema_type_to_str(sema, already, gbuf, sizeof(gbuf));
            SPL_ERROR(&n->dbg, "type mismatch: node kind=%d already typed as %s, expected %s",
                      (int)n->kind, gbuf, ebuf);
            sema->error_count++;
            return 0;
        }
        /* 清空 resolved，走未定型路径，让递归按 expected 下推子节点 */
        n->resolved_lang_tid = 0;
    }

    /* 未定型的构造性节点 */
    switch (n->kind) {

    case SPL_AST_EXPR_UNARY: {
        /* ADDRESS / DEREF 的结果类型由操作数决定，不能用 expected 反向定型。
         * 但不能直接 return ——— 那会绕过 expected 兼容性检查。
         * 走 break 落到兜底：infer 后做 is_subtype / comptime 判定。 */
        if (n->unary.op == SPL_UNARY_OP_ADDRESS || n->unary.op == SPL_UNARY_OP_DEREF)
            break;
        if (!sema_coerce(sema, n->unary.operand, expected))
            return 0;
        n->resolved_lang_tid = expected;
        return expected;
    }

    case SPL_AST_EXPR_BINARY: {
        spl_binary_op_t op = n->binary.op;

        if (op == SPL_OP_ASSIGN || (op >= SPL_OP_ASSIGN_ADD && op <= SPL_OP_ASSIGN_RSHIFT)) {
            spl_lang_type_id_t lt = sema_infer(sema, n->binary.left);
            if (!lt)
                return 0;
            if (!sema_coerce(sema, n->binary.right, lt))
                return 0;
            n->resolved_lang_tid = lt;
            return lt;
        }

        if (op == SPL_OP_BOOL_OR || op == SPL_OP_BOOL_AND) {
            spl_lang_type_id_t bt = spl_lang_make_bool(sema->type);
            if (!sema_coerce(sema, n->binary.left, bt))
                return 0;
            if (!sema_coerce(sema, n->binary.right, bt))
                return 0;
            n->resolved_lang_tid = bt;
            return bt;
        }

        if (op == SPL_OP_CMP_EQ || op == SPL_OP_CMP_NE || op == SPL_OP_CMP_LT ||
            op == SPL_OP_CMP_LE || op == SPL_OP_CMP_GT || op == SPL_OP_CMP_GE) {
            spl_lang_type_id_t lt = sema_infer(sema, n->binary.left);
            spl_lang_type_id_t rt = sema_infer(sema, n->binary.right);
            if (!lt || !rt)
                return 0;
            spl_lang_type_id_t common = (lt == rt) ? lt : spl_lang_type_join(sema->type, lt, rt);
            if (!common) {
                char lbuf[128], rbuf[128];
                sema_type_to_str(sema, lt, lbuf, sizeof(lbuf));
                sema_type_to_str(sema, rt, rbuf, sizeof(rbuf));
                SPL_ERROR(&n->dbg, "comparison operands type mismatch: lhs=%s rhs=%s", lbuf, rbuf);
                sema->error_count++;
                return 0;
            }
            sema_coerce(sema, n->binary.left, common);
            sema_coerce(sema, n->binary.right, common);
            spl_lang_type_id_t b = spl_lang_make_bool(sema->type);
            n->resolved_lang_tid = b;
            return b;
        }

        /* ptr +/- int：expected 是 ptr 且左侧推断为 ptr。
         * 右侧保留原整型；仅 comptime_int（bits==0）收紧到 isize。 */
        if (op == SPL_OP_ADD || op == SPL_OP_SUB) {
            spl_lang_type_node_t *en = spl_lang_type_node(sema->type, expected);
            if (en && en->kind == SPL_LANG_TYPE_PTR) {
                spl_lang_type_id_t lt = sema_infer(sema, n->binary.left);
                spl_lang_type_node_t *ln = spl_lang_type_node(sema->type, lt);
                if (ln && ln->kind == SPL_LANG_TYPE_PTR) {
                    spl_lang_type_id_t rt = sema_infer(sema, n->binary.right);
                    spl_lang_type_node_t *rn = spl_lang_type_node(sema->type, rt);
                    if (!rn || rn->kind != SPL_LANG_TYPE_INT) {
                        SPL_ERROR(&n->dbg, "pointer offset must be integer");
                        sema->error_count++;
                        return 0;
                    }
                    spl_type_node_t *rn_ir = spl_type_node(sema->type, rn->ir_type_id);
                    if (rn_ir && rn_ir->int_type.bits == 0) {
                        spl_lang_type_id_t it =
                            spl_lang_make_int(sema->type, sizeof(void *) * 8, 1);
                        if (!sema_coerce(sema, n->binary.right, it))
                            return 0;
                    }
                    n->resolved_lang_tid = expected;
                    return expected;
                }
            }
        }

        if (!sema_coerce(sema, n->binary.left, expected))
            return 0;
        if (!sema_coerce(sema, n->binary.right, expected))
            return 0;
        n->resolved_lang_tid = expected;
        return expected;
    }

    case SPL_AST_EXPR_ARRAY_LIT: {
        spl_lang_type_node_t *en = spl_lang_type_node(sema->type, expected);
        if (en && en->kind == SPL_LANG_TYPE_ARRAY) {
            spl_lang_type_id_t et = en->extra.elem;
            for (usize i = 0; i < vec_size(n->array_literal.elems); ++i)
                if (!sema_coerce(sema, vec_at(n->array_literal.elems, i), et))
                    return 0;
            n->resolved_lang_tid = expected;
            return expected;
        }
        break;
    }

    case SPL_AST_EXPR_TUPLE: {
        spl_lang_type_node_t *en = spl_lang_type_node(sema->type, expected);
        if (en && en->kind == SPL_LANG_TYPE_TUPLE) {
            usize nelems = vec_size(n->tuple.elems);
            usize ntypes = vec_size(en->extra.elems);
            if (nelems != ntypes) {
                SPL_ERROR(&n->dbg, "tuple arity mismatch (expected %zu, got %zu)", ntypes, nelems);
                sema->error_count++;
                return 0;
            }
            for (usize i = 0; i < nelems; ++i) {
                spl_lang_type_id_t et = vec_at(en->extra.elems, i);
                if (!sema_coerce(sema, vec_at(n->tuple.elems, i), et))
                    return 0;
            }
            n->resolved_lang_tid = expected;
            return expected;
        }
        break;
    }

    case SPL_AST_EXPR_AGGREGATE_LIT: {
        spl_lang_type_node_t *en = spl_lang_type_node(sema->type, expected);
        if (!en || (en->kind != SPL_LANG_TYPE_STRUCT && en->kind != SPL_LANG_TYPE_UNION &&
                    en->kind != SPL_LANG_TYPE_ENUM))
            break;

        /* 有名字时，名字必须与 expected 指向同一类型 */
        if (n->aggregate_literal.name) {
            spl_symbol_t sym;
            if (!spl_scope_find(sema->scope, n->aggregate_literal.name, &sym)) {
                SPL_ERROR(&n->dbg, "unknown type `%s`", n->aggregate_literal.name);
                sema->error_count++;
                return 0;
            }
            spl_def_node_t *def = spl_def_node(sema->type, sym.node);
            if (!def || def->lang_id != expected) {
                SPL_ERROR(&n->dbg, "aggregate `%s` does not match expected type",
                          n->aggregate_literal.name);
                sema->error_count++;
                return 0;
            }
        }

        spl_type_id_t agg_ir = spl_lang_type_get_ir_type(sema->type, expected);
        spl_type_node_t *irn = spl_type_node(sema->type, agg_ir);
        if (!irn) {
            SPL_ERROR(&n->dbg, "aggregate type unresolved");
            sema->error_count++;
            return 0;
        }

        if (en->kind == SPL_LANG_TYPE_ENUM) {
            if (vec_size(n->aggregate_literal.fields) != 1) {
                SPL_ERROR(&n->dbg, "enum literal must have exactly one variant");
                sema->error_count++;
                return 0;
            }
            spl_ast_node_t *item = spl_ast_node(sema->ast, vec_at(n->aggregate_literal.fields, 0));
            if (!item || item->kind != SPL_AST_STRUCT_INIT_ITEM) {
                SPL_ERROR(&n->dbg, "invalid enum literal");
                sema->error_count++;
                return 0;
            }
            usize idx = 0;
            if (!spl_type_agg_member_idx(sema->type, agg_ir, item->struct_init_item.name, &idx)) {
                SPL_ERROR(&item->dbg, "no variant `%s`", item->struct_init_item.name);
                sema->error_count++;
                return 0;
            }
            usize field_tid_ir = vec_at(irn->agg_type.variants, idx).type_id;
            spl_lang_type_id_t ft = sema_lang_from_ir(sema, field_tid_ir);
            if (ft && item->struct_init_item.expr) {
                if (!sema_coerce(sema, item->struct_init_item.expr, ft))
                    return 0;
            }
            n->resolved_lang_tid = expected;
            return expected;
        }

        for (usize i = 0; i < vec_size(n->aggregate_literal.fields); ++i) {
            spl_ast_node_t *item = spl_ast_node(sema->ast, vec_at(n->aggregate_literal.fields, i));
            if (!item || item->kind != SPL_AST_STRUCT_INIT_ITEM)
                continue;
            usize idx = 0;
            if (!spl_type_agg_member_idx(sema->type, agg_ir, item->struct_init_item.name, &idx)) {
                SPL_ERROR(&item->dbg, "no field `%s`", item->struct_init_item.name);
                sema->error_count++;
                continue;
            }
            usize field_tid_ir = vec_at(irn->agg_type.variants, idx).type_id;
            spl_lang_type_id_t ft = sema_lang_from_ir(sema, field_tid_ir);
            if (ft && item->struct_init_item.expr) {
                if (!sema_coerce(sema, item->struct_init_item.expr, ft))
                    return 0;
            }
        }
        n->resolved_lang_tid = expected;
        return expected;
    }

    case SPL_AST_EXPR_IF: {
        spl_lang_type_id_t bt = spl_lang_make_bool(sema->type);
        sema_coerce(sema, n->if_expr.cond, bt);
        if (n->if_expr.then_block)
            sema_coerce(sema, n->if_expr.then_block, expected);
        if (n->if_expr.else_branch)
            sema_coerce(sema, n->if_expr.else_branch, expected);
        n->resolved_lang_tid = expected;
        return expected;
    }

    case SPL_AST_EXPR_LOOP: {
        spl_lang_type_id_t saved = sema->current_loop_break_tid;
        sema->current_loop_break_tid = expected;
        sema_infer(sema, ref);
        sema->current_loop_break_tid = saved;
        n->resolved_lang_tid = expected;
        return expected;
    }

    case SPL_AST_EXPR_BLOCK: {
        sema_push_scope(sema);
        for (usize i = 0; i < vec_size(n->block.stmts); ++i)
            sema_infer(sema, vec_at(n->block.stmts, i));
        spl_lang_type_id_t r = 0;
        if (n->block.tail_expr) {
            spl_lang_type_id_t t = sema_coerce(sema, n->block.tail_expr, expected);
            if (!t) {
                sema_pop_scope(sema);
                return 0;
            }
            r = t;
        } else {
            r = spl_lang_make_unit(sema->type);
        }
        sema_pop_scope(sema);
        n->resolved_lang_tid = r;
        return r;
    }

    default:
        break;
    }

    /* 兜底：infer 后按子类型 / comptime 判定 */
    spl_lang_type_id_t from = sema_infer(sema, ref);
    if (!from)
        return 0;
    if (from == expected)
        return expected;

    spl_lang_type_node_t *from_n = spl_lang_type_node(sema->type, from);
    spl_lang_type_node_t *to_n = spl_lang_type_node(sema->type, expected);
    spl_type_node_t *from_ir = from_n ? spl_type_node(sema->type, from_n->ir_type_id) : NULL;
    spl_type_node_t *to_ir = to_n ? spl_type_node(sema->type, to_n->ir_type_id) : NULL;

    bool from_comptime_int =
        from_n && from_n->kind == SPL_LANG_TYPE_INT && from_ir && from_ir->int_type.bits == 0;
    bool from_comptime_float =
        from_n && from_n->kind == SPL_LANG_TYPE_FLOAT && from_ir && from_ir->float_type.bits == 0;
    if (from_comptime_int && to_n && to_n->kind == SPL_LANG_TYPE_INT) {
        uint32_t bits = to_ir ? (uint32_t)to_ir->int_type.bits : 0;
        if (n->kind == SPL_AST_EXPR_INT_LIT && bits != 0 &&
            !spl_lang_mpa_int_fits(sema->type, expected, n->int_lit)) {
            SPL_ERROR(&n->dbg, "comptime value does not fit target type");
            sema->error_count++;
            return 0;
        }
        n->resolved_lang_tid = expected;
        return expected;
    }
    if (from_comptime_float && to_n && to_n->kind == SPL_LANG_TYPE_FLOAT) {
        n->resolved_lang_tid = expected;
        return expected;
    }

    if (spl_lang_type_is_subtype(sema->type, from, expected)) {
        n->expected_lang_tid = expected;
        return expected;
    }

    char ebuf[128], gbuf[128];
    sema_type_to_str(sema, expected, ebuf, sizeof(ebuf));
    sema_type_to_str(sema, from, gbuf, sizeof(gbuf));
    SPL_ERROR(&n->dbg, "type mismatch: expect %s, got %s (node kind=%d)", ebuf, gbuf, (int)n->kind);
    sema->error_count++;
    return 0;
}

static spl_lang_type_id_t sema_infer(spl_sema_t *sema, spl_ast_node_ref_t ref) {
    if (ref == 0)
        return 0;
    spl_ast_node_t *n = spl_ast_node(sema->ast, ref);
    if (!n)
        return 0;

    spl_ast_node_ref_vec_t *raw = node_attr_list(n);
    if (raw && vec_size(*raw) > 0)
        sema_resolve_attrs(sema, raw, &n->attrs);

    switch (n->kind) {

    /* ---------- 字面量 ---------- */
    case SPL_AST_EXPR_INT_LIT: {
        spl_lang_type_id_t t = spl_lang_make_int(sema->type, 0, 1);
        n->resolved_lang_tid = t;
        return t;
    }
    case SPL_AST_EXPR_FLOAT_LIT: {
        spl_lang_type_id_t t = spl_lang_make_float(sema->type, 0);
        n->resolved_lang_tid = t;
        return t;
    }
    case SPL_AST_EXPR_CHAR_LIT: {
        spl_lang_type_id_t t = spl_lang_make_int(sema->type, 8, 0);
        n->resolved_lang_tid = t;
        return t;
    }
    case SPL_AST_EXPR_STRING_LIT: {
        spl_lang_type_id_t u8 = spl_lang_make_int(sema->type, 8, 0);
        spl_lang_type_id_t s = spl_lang_make_slice(sema->type, u8);
        n->resolved_lang_tid = s;
        return s;
    }
    case SPL_AST_EXPR_BOOL_LIT: {
        spl_lang_type_id_t t = spl_lang_make_bool(sema->type);
        n->resolved_lang_tid = t;
        return t;
    }
    case SPL_AST_EXPR_NULL_LIT: {
        spl_lang_type_id_t nv = spl_lang_make_never(sema->type);
        spl_lang_type_id_t p = spl_lang_make_ptr(sema->type, nv);
        n->resolved_lang_tid = p;
        return p;
    }
    case SPL_AST_EXPR_UNDEFINED_LIT: {
        spl_lang_type_id_t t = spl_lang_make_never(sema->type);
        n->resolved_lang_tid = t;
        return t;
    }

    /* ---------- IDENT：同时写 def_id 和 lang_tid 副本 ---------- */
    case SPL_AST_EXPR_IDENT: {
        const char *name = n->ident.name;
        spl_symbol_t sym;
        if (!spl_scope_find(sema->scope, name, &sym)) {
            SPL_ERROR(&n->dbg, "undefined identifier `%s`", name);
            sema->error_count++;
            return 0;
        }
        if (sym.node == 0) {
            SPL_ERROR(&n->dbg, "identifier `%s` has no definition", name);
            sema->error_count++;
            return 0;
        }
        n->resolved_def_id = sym.node;
        spl_lang_type_id_t t = sema_eval_decl(sema, sym.node);
        n->resolved_lang_tid = t;
        return t;
    }

    /* ---------- UNARY ---------- */
    case SPL_AST_EXPR_UNARY: {
        spl_lang_type_id_t op = sema_infer(sema, n->unary.operand);
        if (op == 0)
            return 0;
        spl_lang_type_node_t *tn = spl_lang_type_node(sema->type, op);
        if (!tn)
            return 0;

        switch (n->unary.op) {
        case SPL_UNARY_OP_MINUS:
            if (tn->kind != SPL_LANG_TYPE_INT && tn->kind != SPL_LANG_TYPE_FLOAT) {
                SPL_ERROR(&n->dbg, "unary minus requires numeric operand");
                sema->error_count++;
                return 0;
            }
            n->resolved_lang_tid = op;
            return op;
        case SPL_UNARY_OP_BIT_NOT:
            if (tn->kind != SPL_LANG_TYPE_INT) {
                SPL_ERROR(&n->dbg, "bitwise not requires integer operand");
                sema->error_count++;
                return 0;
            }
            n->resolved_lang_tid = op;
            return op;
        case SPL_UNARY_OP_NOT: {
            spl_lang_type_id_t bt = spl_lang_make_bool(sema->type);
            sema_coerce(sema, n->unary.operand, bt);
            n->resolved_lang_tid = bt;
            return bt;
        }
        case SPL_UNARY_OP_ADDRESS: {
            spl_lang_type_id_t p = spl_lang_make_ptr(sema->type, op);
            n->resolved_lang_tid = p;
            return p;
        }
        case SPL_UNARY_OP_DEREF: {
            if (tn->kind != SPL_LANG_TYPE_PTR) {
                SPL_ERROR(&n->dbg, "deref requires pointer operand");
                sema->error_count++;
                return 0;
            }
            spl_lang_type_id_t elem = tn->extra.elem;
            n->resolved_lang_tid = elem;
            return elem;
        }
        default:
            UNREACHABLE();
        }
    }

    /* ---------- BINARY ---------- */
    case SPL_AST_EXPR_BINARY: {
        spl_binary_op_t op = n->binary.op;

        /* 赋值 / 复合赋值 */
        if (op == SPL_OP_ASSIGN || (op >= SPL_OP_ASSIGN_ADD && op <= SPL_OP_ASSIGN_RSHIFT)) {
            spl_lang_type_id_t lt = sema_infer(sema, n->binary.left);
            if (!lt)
                return 0;
            sema_coerce(sema, n->binary.right, lt);
            n->resolved_lang_tid = lt;
            return lt;
        }

        /* 逻辑 */
        if (op == SPL_OP_BOOL_OR || op == SPL_OP_BOOL_AND) {
            spl_lang_type_id_t bt = spl_lang_make_bool(sema->type);
            sema_coerce(sema, n->binary.left, bt);
            sema_coerce(sema, n->binary.right, bt);
            n->resolved_lang_tid = bt;
            return bt;
        }

        if (op == SPL_OP_CMP_EQ || op == SPL_OP_CMP_NE || op == SPL_OP_CMP_LT ||
            op == SPL_OP_CMP_LE || op == SPL_OP_CMP_GT || op == SPL_OP_CMP_GE) {
            spl_lang_type_id_t lt = sema_infer(sema, n->binary.left);
            spl_lang_type_id_t rt = sema_infer(sema, n->binary.right);
            if (!lt || !rt)
                return 0;

            spl_lang_type_id_t common = (lt == rt) ? lt : spl_lang_type_join(sema->type, lt, rt);
            if (!common) {
                char lbuf[128], rbuf[128];
                sema_type_to_str(sema, lt, lbuf, sizeof(lbuf));
                sema_type_to_str(sema, rt, rbuf, sizeof(rbuf));
                SPL_ERROR(&n->dbg, "comparison operands type mismatch: lhs=%s rhs=%s", lbuf, rbuf);
                sema->error_count++;
                return 0;
            }

            sema_coerce(sema, n->binary.left, common);
            sema_coerce(sema, n->binary.right, common);

            spl_lang_type_id_t b = spl_lang_make_bool(sema->type);
            n->resolved_lang_tid = b;
            return b;
        }

        /* Range */
        if (op == SPL_OP_RANGE) {
            sema_infer(sema, n->binary.left);
            sema_infer(sema, n->binary.right);
            spl_lang_type_id_t i64 = spl_lang_make_int(sema->type, 64, 1);
            spl_lang_type_id_t r = spl_lang_make_range(sema->type, i64);
            n->resolved_lang_tid = r;
            return r;
        }

        /* 移位：结果 = 左类型 */
        if (op == SPL_OP_LSHIFT || op == SPL_OP_RSHIFT) {
            spl_lang_type_id_t lt = sema_infer(sema, n->binary.left);
            if (!lt)
                return 0;
            spl_lang_type_node_t *ln = spl_lang_type_node(sema->type, lt);
            if (!ln || ln->kind != SPL_LANG_TYPE_INT) {
                SPL_ERROR(&n->dbg, "shift requires integer operands");
                sema->error_count++;
                return 0;
            }
            sema_infer(sema, n->binary.right);
            n->resolved_lang_tid = lt;
            return lt;
        }

        spl_lang_type_id_t lt = sema_infer(sema, n->binary.left);
        spl_lang_type_id_t rt = sema_infer(sema, n->binary.right);
        if (!lt || !rt)
            return 0;

        spl_lang_type_node_t *ln = spl_lang_type_node(sema->type, lt);
        spl_lang_type_node_t *rn = spl_lang_type_node(sema->type, rt);

        /* ptr +/- int 特判：右侧保留自己的整型；
         * 仅当右操作数是 comptime_int（bits==0）时收紧到 isize，
         * 避免 comptime 类型泄漏到 IR。 */
        if (ln && ln->kind == SPL_LANG_TYPE_PTR && rn && rn->kind == SPL_LANG_TYPE_INT &&
            (op == SPL_OP_ADD || op == SPL_OP_SUB)) {
            spl_type_node_t *rn_ir = spl_type_node(sema->type, rn->ir_type_id);
            if (rn_ir && rn_ir->int_type.bits == 0) {
                spl_lang_type_id_t it = spl_lang_make_int(sema->type, sizeof(void *) * 8, 1);
                sema_coerce(sema, n->binary.right, it);
            }
            n->resolved_lang_tid = lt;
            return lt;
        }

        spl_lang_type_id_t common = (lt == rt) ? lt : spl_lang_type_join(sema->type, lt, rt);
        if (!common) {
            char lbuf[128], rbuf[128];
            sema_type_to_str(sema, lt, lbuf, sizeof(lbuf));
            sema_type_to_str(sema, rt, rbuf, sizeof(rbuf));
            SPL_ERROR(&n->dbg, "operand types cannot be joined: lhs=%s rhs=%s", lbuf, rbuf);
            sema->error_count++;
            return 0;
        }

        sema_coerce(sema, n->binary.left, common);
        sema_coerce(sema, n->binary.right, common);

        n->resolved_lang_tid = common;
        return common;
    }

    /* ---------- CALL ---------- */
    case SPL_AST_EXPR_CALL: {
        spl_ast_node_t *callee = spl_ast_node(sema->ast, n->call.callee);
        if (callee && callee->kind == SPL_AST_EXPR_IDENT) {
            spl_intrin_t in = spl_intrin_lookup_call(callee->ident.name);
            if (in != SPL_INTRIN_NONE) {
                spl_lang_type_id_t t = sema_intrin_call(sema, n, in, &n->call.args);
                n->resolved_lang_tid = t;
                return t;
            }
        }

        spl_lang_type_id_t callee_tid = sema_infer(sema, n->call.callee);
        spl_lang_type_node_t *fn = spl_lang_type_node(sema->type, callee_tid);
        if (!fn || fn->kind != SPL_LANG_TYPE_FN) {
            SPL_ERROR(&n->dbg, "callee is not a function");
            sema->error_count++;
            return 0;
        }

        bool has_varargs = false;
        usize fixed = vec_size(fn->extra.fn.params);
        if (fixed > 0) {
            spl_lang_type_id_t last = vec_at(fn->extra.fn.params, fixed - 1);
            spl_lang_type_node_t *ln = spl_lang_type_node(sema->type, last);
            if (ln && ln->kind == SPL_LANG_TYPE_VARARGS) {
                has_varargs = true;
                fixed--;
            }
        }

        usize nargs = vec_size(n->call.args);
        if (has_varargs) {
            if (nargs < fixed) {
                SPL_ERROR(&n->dbg, "too few arguments (expected at least %zu)", fixed);
                sema->error_count++;
            }
        } else if (nargs != fixed) {
            SPL_ERROR(&n->dbg, "argument count mismatch (expected %zu, got %zu)", fixed, nargs);
            sema->error_count++;
        }

        /* 固定参数：check 到形参类型 */
        for (usize i = 0; i < nargs && i < fixed; ++i) {
            spl_lang_type_id_t pt =
                vec_at(spl_lang_type_node(sema->type, callee_tid)->extra.fn.params, i);
            if (!sema_coerce(sema, vec_at(n->call.args, i), pt))
                return 0;
        }

        if (has_varargs) {
            for (usize i = fixed; i < nargs; ++i) {
                if (!sema_infer(sema, vec_at(n->call.args, i)))
                    return 0;
            }
        }

        spl_lang_type_id_t ret = fn->extra.fn.ret;
        n->resolved_lang_tid = ret;
        return ret;
    }

    /* ---------- FIELD ---------- */
    case SPL_AST_EXPR_FIELD: {
        spl_lang_type_id_t obj_tid = sema_infer(sema, n->field.obj);
        spl_lang_type_node_t *obj = spl_lang_type_node(sema->type, obj_tid);
        if (!obj)
            return 0;

        spl_intrin_t in = spl_intrin_lookup_field(obj->kind, n->field.field);
        if (in != SPL_INTRIN_NONE) {
            spl_lang_type_id_t t = sema_intrin_field(sema, n, in);
            n->resolved_lang_tid = t;
            return t;
        }

        spl_lang_type_id_t agg_lang = obj_tid;
        if (obj->kind == SPL_LANG_TYPE_PTR)
            agg_lang = obj->extra.elem;
        spl_lang_type_node_t *agg = spl_lang_type_node(sema->type, agg_lang);
        if (!agg) {
            SPL_ERROR(&n->dbg, "field access on invalid type");
            sema->error_count++;
            return 0;
        }

        spl_type_id_t agg_ir = spl_lang_type_get_ir_type(sema->type, agg_lang);
        if (agg_ir) {
            const spl_type_member_t *m = spl_type_agg_member(sema->type, agg_ir, n->field.field);
            if (m) {
                spl_lang_type_id_t ft = sema_lang_from_ir(sema, m->type_id);
                if (!ft) {
                    SPL_ERROR(&n->dbg, "cannot resolve field type");
                    sema->error_count++;
                    return 0;
                }
                n->resolved_lang_tid = ft;
                return ft;
            }
        }

        for (usize i = 0; i < vec_size(agg->methods); ++i) {
            spl_lang_method_t *meth = &vec_at(agg->methods, i);
            if (strcmp(meth->name, n->field.field) != 0)
                continue;
            n->resolved_def_id = meth->def_id;
            spl_lang_type_id_t t = sema_eval_decl(sema, meth->def_id);
            n->resolved_lang_tid = t;
            return t;
        }

        SPL_ERROR(&n->dbg, "no field `%s`", n->field.field);
        sema->error_count++;
        return 0;
    }

    /* ---------- INDEX ---------- */
    case SPL_AST_EXPR_INDEX: {
        spl_lang_type_id_t obj_tid = sema_infer(sema, n->index.obj);
        sema_infer(sema, n->index.index);
        spl_lang_type_node_t *obj = spl_lang_type_node(sema->type, obj_tid);
        if (!obj)
            return 0;
        spl_lang_type_id_t elem = 0;
        switch (obj->kind) {
        case SPL_LANG_TYPE_ARRAY:
        case SPL_LANG_TYPE_SLICE:
        case SPL_LANG_TYPE_RANGE:
        case SPL_LANG_TYPE_PTR:
            elem = obj->extra.elem;
            break;
        case SPL_LANG_TYPE_TUPLE: {
            spl_ast_node_t *idx_node = spl_ast_node(sema->ast, n->index.index);
            if (!idx_node || idx_node->kind != SPL_AST_EXPR_INT_LIT) {
                SPL_ERROR(&n->dbg, "tuple index must be an integer literal");
                sema->error_count++;
                return 0;
            }
            isize i = (isize)idx_node->int_lit.bits;
            if (i < 0 || (usize)i >= vec_size(obj->extra.elems)) {
                SPL_ERROR(&n->dbg, "tuple index out of range");
                sema->error_count++;
                return 0;
            }
            elem = vec_at(obj->extra.elems, (usize)i);
            break;
        }
        default:
            SPL_ERROR(&n->dbg, "index base must be array/slice/ptr/range/tuple");
            sema->error_count++;
            return 0;
        }
        n->resolved_lang_tid = elem;
        return elem;
    }

    /* ---------- SLICE ---------- */
    case SPL_AST_EXPR_SLICE: {
        spl_lang_type_id_t obj_tid = sema_infer(sema, n->slice.obj);
        if (n->slice.begin)
            sema_infer(sema, n->slice.begin);
        if (n->slice.end)
            sema_infer(sema, n->slice.end);
        spl_lang_type_node_t *obj = spl_lang_type_node(sema->type, obj_tid);
        if (!obj)
            return 0;
        spl_lang_type_id_t elem = 0;
        if (obj->kind == SPL_LANG_TYPE_ARRAY || obj->kind == SPL_LANG_TYPE_PTR ||
            obj->kind == SPL_LANG_TYPE_SLICE) {
            elem = obj->extra.elem;
        } else {
            SPL_ERROR(&n->dbg, "slice base must be array/ptr/slice");
            sema->error_count++;
            return 0;
        }
        spl_lang_type_id_t s = spl_lang_make_slice(sema->type, elem);
        n->resolved_lang_tid = s;
        return s;
    }

    /* ---------- CAST ---------- */
    case SPL_AST_EXPR_CAST: {
        spl_lang_type_id_t dst_lang = sema_infer(sema, n->cast.type);
        if (!dst_lang)
            return 0;
        spl_lang_type_id_t src_lang = sema_infer(sema, n->cast.expr);
        if (!src_lang)
            return 0;

        spl_lang_type_node_t *sn = spl_lang_type_node(sema->type, src_lang);
        spl_type_node_t *sir = sn ? spl_type_node(sema->type, sn->ir_type_id) : NULL;
        bool src_is_literal_int =
            sn && sn->kind == SPL_LANG_TYPE_INT && sir && sir->int_type.bits == 0;
        bool src_is_literal_float =
            sn && sn->kind == SPL_LANG_TYPE_FLOAT && sir && sir->float_type.bits == 0;

        if (src_is_literal_int || src_is_literal_float) {
            /* 字面量目标物化：允许任意宽度，as 会按其语义处理 */
            spl_ast_node_t *src_node = spl_ast_node(sema->ast, n->cast.expr);
            if (src_node && (src_node->kind == SPL_AST_EXPR_INT_LIT ||
                             src_node->kind == SPL_AST_EXPR_FLOAT_LIT)) {
                src_node->resolved_lang_tid = dst_lang;
            } else if (!sema_coerce(sema, n->cast.expr, dst_lang)) {
                return 0;
            }
            n->resolved_lang_tid = dst_lang;
            return dst_lang;
        }

        spl_type_id_t ft = spl_lang_type_get_ir_type(sema->type, src_lang);
        spl_type_id_t tt = spl_lang_type_get_ir_type(sema->type, dst_lang);
        if (!ft || !tt) {
            SPL_ERROR(&n->dbg, "as: unresolved source or target type");
            sema->error_count++;
            return 0;
        }
        spl_intrin_t in = spl_intrin_lookup_cast(sema->type, ft, tt);
        if (in == SPL_INTRIN_NONE) {
            SPL_ERROR(&n->dbg, "as: invalid conversion (not supported by as)");
            sema->error_count++;
            return 0;
        }
        n->resolved_lang_tid = dst_lang;
        return dst_lang;
    }

    /* ---------- TUPLE ---------- */
    case SPL_AST_EXPR_TUPLE: {
        spl_lang_type_id_vec_t es;
        vec_init(es);
        for (usize i = 0; i < vec_size(n->tuple.elems); ++i)
            vec_push(es, sema_infer(sema, vec_at(n->tuple.elems, i)));
        spl_lang_type_id_t t =
            spl_lang_make_tuple(sema->type, vec_unsafe_get_data(es), vec_size(es));
        vec_free(es);
        n->resolved_lang_tid = t;
        return t;
    }

    /* ---------- ARRAY_LIT ---------- */
    case SPL_AST_EXPR_ARRAY_LIT: {
        spl_lang_type_id_t elem_t = 0;
        if (n->array_literal.elem_type)
            elem_t = sema_infer(sema, n->array_literal.elem_type);

        usize nelems = vec_size(n->array_literal.elems);
        for (usize i = 0; i < nelems; ++i) {
            spl_lang_type_id_t et = sema_infer(sema, vec_at(n->array_literal.elems, i));
            if (!et)
                return 0;
            if (elem_t == 0) {
                elem_t = et;
            } else {
                spl_lang_type_id_t c =
                    (elem_t == et) ? elem_t : spl_lang_type_join(sema->type, elem_t, et);
                if (c)
                    elem_t = c;
            }
        }
        if (elem_t == 0)
            elem_t = spl_lang_make_infer(sema->type);
        usize len = n->array_literal.is_underscore_len ? nelems
                    : n->array_literal.has_len         ? (usize)n->array_literal.len
                                                       : nelems;
        spl_lang_type_id_t arr = spl_lang_make_array(sema->type, elem_t, len);
        n->resolved_lang_tid = arr;
        return arr;
    }

    /* ---------- AGGREGATE_LIT ---------- */
    case SPL_AST_EXPR_AGGREGATE_LIT: {
        const char *type_name = n->aggregate_literal.name;
        if (!type_name) {
            spl_lang_type_id_t inf = spl_lang_make_infer(sema->type);
            n->resolved_lang_tid = inf;
            return inf;
        }
        spl_symbol_t sym;
        if (!spl_scope_find(sema->scope, type_name, &sym)) {
            SPL_ERROR(&n->dbg, "unknown type `%s`", type_name);
            sema->error_count++;
            return 0;
        }
        spl_def_node_t *def = spl_def_node(sema->type, sym.node);
        if (!def || !def->lang_id) {
            SPL_ERROR(&n->dbg, "type `%s` not resolved", type_name);
            sema->error_count++;
            return 0;
        }
        spl_lang_type_id_t agg = def->lang_id;
        spl_lang_type_node_t *an = spl_lang_type_node(sema->type, agg);
        if (!an || (an->kind != SPL_LANG_TYPE_STRUCT && an->kind != SPL_LANG_TYPE_UNION &&
                    an->kind != SPL_LANG_TYPE_ENUM)) {
            SPL_ERROR(&n->dbg, "`%s` is not a struct/union/enum", type_name);
            sema->error_count++;
            return 0;
        }
        if (an->kind == SPL_LANG_TYPE_ENUM && vec_size(n->aggregate_literal.fields) != 1) {
            SPL_ERROR(&n->dbg, "enum literal must have exactly one variant");
            sema->error_count++;
            return 0;
        }
        spl_type_id_t agg_ir = spl_lang_type_get_ir_type(sema->type, agg);
        spl_type_node_t *irn = spl_type_node(sema->type, agg_ir);
        if (irn) {
            for (usize i = 0; i < vec_size(n->aggregate_literal.fields); ++i) {
                spl_ast_node_t *item =
                    spl_ast_node(sema->ast, vec_at(n->aggregate_literal.fields, i));
                if (!item || item->kind != SPL_AST_STRUCT_INIT_ITEM)
                    continue;
                usize idx = 0;
                if (!spl_type_agg_member_idx(sema->type, agg_ir, item->struct_init_item.name,
                                             &idx)) {
                    SPL_ERROR(&item->dbg, "no field `%s`", item->struct_init_item.name);
                    sema->error_count++;
                    continue;
                }
                usize field_tid_ir = vec_at(irn->agg_type.variants, idx).type_id;
                spl_lang_type_id_t ft = sema_lang_from_ir(sema, field_tid_ir);
                if (ft && item->struct_init_item.expr)
                    sema_coerce(sema, item->struct_init_item.expr, ft);
            }
        }
        n->resolved_lang_tid = agg;
        return agg;
    }

    /* ---------- COMPTIME_CALL ---------- */
    case SPL_AST_EXPR_COMPTIME_CALL: {
        spl_intrin_t in = spl_intrin_lookup_call(n->comptime_call.name);
        if (in == SPL_INTRIN_NONE) {
            SPL_ERROR(&n->dbg, "unknown comptime call `@%s`", n->comptime_call.name);
            sema->error_count++;
            return 0;
        }
        spl_lang_type_id_t t = sema_intrin_call(sema, n, in, &n->comptime_call.args);
        n->resolved_lang_tid = t;
        return t;
    }

    /* ---------- BLOCK ---------- */
    case SPL_AST_EXPR_BLOCK: {
        sema_push_scope(sema);
        spl_lang_type_id_t last = 0;
        for (usize i = 0; i < vec_size(n->block.stmts); ++i)
            sema_infer(sema, vec_at(n->block.stmts, i));
        if (n->block.tail_expr)
            last = sema_infer(sema, n->block.tail_expr);
        sema_pop_scope(sema);
        n->resolved_lang_tid = last;
        return last;
    }

    /* ---------- IF ---------- */
    case SPL_AST_EXPR_IF: {
        spl_lang_type_id_t bt = spl_lang_make_bool(sema->type);
        sema_coerce(sema, n->if_expr.cond, bt);

        spl_lang_type_id_t then_t =
            n->if_expr.then_block ? sema_infer(sema, n->if_expr.then_block) : 0;
        spl_lang_type_id_t else_t =
            n->if_expr.else_branch ? sema_infer(sema, n->if_expr.else_branch) : 0;
        spl_lang_type_id_t result = 0;
        if (then_t && else_t)
            result = (then_t == else_t) ? then_t : spl_lang_type_join(sema->type, then_t, else_t);
        else
            result = then_t ? then_t : else_t;
        n->resolved_lang_tid = result;
        return result;
    }

    /* ---------- IFVAR / WHILE / LOOP / FOR / MATCH ---------- */
    case SPL_AST_EXPR_IFVAR: {
        sema_infer(sema, n->ifvar_expr.var_decl);
        if (n->ifvar_expr.then_block)
            sema_infer(sema, n->ifvar_expr.then_block);
        if (n->ifvar_expr.else_branch)
            sema_infer(sema, n->ifvar_expr.else_branch);
        return 0;
    }
    case SPL_AST_EXPR_WHILE: {
        const char *lbl = NULL;
        if (n->while_expr.label) {
            spl_ast_node_t *ln = spl_ast_node(sema->ast, n->while_expr.label);
            if (ln && ln->kind == SPL_AST_LABEL)
                lbl = ln->label.name;
        }
        vec_push(sema->label_stack, lbl);

        spl_lang_type_id_t bt = spl_lang_make_bool(sema->type);
        sema_coerce(sema, n->while_expr.cond, bt);
        if (n->while_expr.body)
            sema_infer(sema, n->while_expr.body);
        if (n->while_expr.else_branch)
            sema_infer(sema, n->while_expr.else_branch);

        vec_pop(sema->label_stack);
        return 0;
    }
    case SPL_AST_EXPR_LOOP: {
        const char *lbl = NULL;
        if (n->loop_expr.label) {
            spl_ast_node_t *ln = spl_ast_node(sema->ast, n->loop_expr.label);
            if (ln && ln->kind == SPL_AST_LABEL)
                lbl = ln->label.name;
        }
        vec_push(sema->label_stack, lbl);

        if (n->loop_expr.body)
            sema_infer(sema, n->loop_expr.body);

        vec_pop(sema->label_stack);
        return 0;
    }
    case SPL_AST_EXPR_FOR: {
        const char *lbl = NULL;
        if (n->for_expr.label) {
            spl_ast_node_t *ln = spl_ast_node(sema->ast, n->for_expr.label);
            if (ln && ln->kind == SPL_AST_LABEL)
                lbl = ln->label.name;
        }
        vec_push(sema->label_stack, lbl);

        sema_push_scope(sema);
        for (usize i = 0; i < vec_size(n->for_expr.iter_exprs); ++i) {
            spl_lang_type_id_t container_tid = sema_infer(sema, vec_at(n->for_expr.iter_exprs, i));
            spl_lang_type_id_t elem_tid = sema_for_elem_type(sema, container_tid);
            if (i < vec_size(n->for_expr.idents)) {
                spl_ast_node_t *id_node = spl_ast_node(sema->ast, vec_at(n->for_expr.idents, i));
                if (id_node && id_node->kind == SPL_AST_EXPR_IDENT) {
                    const char *var_name = id_node->ident.name;
                    if (strcmp(var_name, "_") != 0) {
                        spl_symbol_t sym = {.name = var_name, .kind = SPL_SYMBOL_KIND_VAR};
                        sym.node = spl_def_alloc(sema->type, SPL_DEF_VAR, var_name, id_node->dbg,
                                                 vec_at(n->for_expr.idents, i));
                        spl_def_resolve(sema->type, sym.node, elem_tid);
                        spl_scope_insert(sema->scope, sema->scope->current_scope, sym);
                        id_node->resolved_def_id = sym.node;
                        id_node->resolved_lang_tid = elem_tid;
                    }
                }
            }
        }
        if (n->for_expr.body)
            sema_infer(sema, n->for_expr.body);
        if (n->for_expr.else_branch)
            sema_infer(sema, n->for_expr.else_branch);
        sema_pop_scope(sema);

        vec_pop(sema->label_stack);
        return 0;
    }
    case SPL_AST_EXPR_MATCH: {
        sema_infer(sema, n->match_expr.matched_expr);
        for (usize i = 0; i < vec_size(n->match_expr.arms); ++i) {
            spl_ast_node_t *arm = spl_ast_node(sema->ast, vec_at(n->match_expr.arms, i));
            if (arm && arm->kind == SPL_AST_MATCH_ARM) {
                sema_infer(sema, arm->match_arm.pattern);
                sema_infer(sema, arm->match_arm.body);
            }
        }
        return 0;
    }

    /* ---------- FN_TYPE ---------- */
    case SPL_AST_EXPR_FN_TYPE: {
        spl_lang_type_id_vec_t ps;
        vec_init(ps);
        for (usize i = 0; i < vec_size(n->fn_type.params); ++i)
            vec_push(ps, sema_infer(sema, vec_at(n->fn_type.params, i)));
        spl_lang_type_id_t ret = sema_infer(sema, n->fn_type.ret_type);
        spl_lang_type_id_t fn =
            spl_lang_make_fn(sema->type, ret, vec_unsafe_get_data(ps), vec_size(ps));
        vec_free(ps);
        n->resolved_lang_tid = fn;
        return fn;
    }

    /* ---------- 类型表达式 ---------- */
    case SPL_AST_TYPE_PATH: {
        const char *name = n->type_path.name;
        spl_lang_type_id_t b = spl_type_lookup_builtin(sema->type, name);
        if (b) {
            n->resolved_lang_tid = b;
            return b;
        }
        spl_symbol_t sym;
        if (!spl_scope_find(sema->scope, name, &sym)) {
            SPL_ERROR(&n->dbg, "type `%s` not found", name);
            sema->error_count++;
            return 0;
        }
        spl_lang_type_id_t t = sema_eval_decl(sema, sym.node);
        n->resolved_lang_tid = t;
        return t;
    }
    case SPL_AST_TYPE_POINTER: {
        spl_lang_type_id_t p = sema_infer(sema, n->type_pointer.pointee);
        spl_lang_type_id_t r = spl_lang_make_ptr(sema->type, p);
        n->resolved_lang_tid = r;
        return r;
    }
    case SPL_AST_TYPE_ARRAY: {
        spl_lang_type_id_t e = sema_infer(sema, n->type_array.elem_type);
        usize len = n->type_array.has_len ? (usize)n->type_array.len : 0;
        spl_lang_type_id_t r = spl_lang_make_array(sema->type, e, len);
        n->resolved_lang_tid = r;
        return r;
    }
    case SPL_AST_TYPE_SLICE: {
        spl_lang_type_id_t e = sema_infer(sema, n->type_slice.elem_type);
        spl_lang_type_id_t r = spl_lang_make_slice(sema->type, e);
        n->resolved_lang_tid = r;
        return r;
    }
    case SPL_AST_TYPE_FN: {
        spl_lang_type_id_vec_t ps;
        vec_init(ps);
        for (usize i = 0; i < vec_size(n->type_fn.params); ++i)
            vec_push(ps, sema_infer(sema, vec_at(n->type_fn.params, i)));
        spl_lang_type_id_t ret = sema_infer(sema, n->type_fn.ret_type);
        spl_lang_type_id_t r =
            spl_lang_make_fn(sema->type, ret, vec_unsafe_get_data(ps), vec_size(ps));
        vec_free(ps);
        n->resolved_lang_tid = r;
        return r;
    }
    case SPL_AST_TYPE_PAREN: {
        usize c = vec_size(n->type_paren.types);
        if (c == 0) {
            spl_lang_type_id_t u = spl_lang_make_unit(sema->type);
            n->resolved_lang_tid = u;
            return u;
        }
        if (c == 1) {
            spl_lang_type_id_t t = sema_infer(sema, vec_at(n->type_paren.types, 0));
            n->resolved_lang_tid = t;
            return t;
        }
        spl_lang_type_id_vec_t es;
        vec_init(es);
        for (usize i = 0; i < c; ++i)
            vec_push(es, sema_infer(sema, vec_at(n->type_paren.types, i)));
        spl_lang_type_id_t t =
            spl_lang_make_tuple(sema->type, vec_unsafe_get_data(es), vec_size(es));
        vec_free(es);
        n->resolved_lang_tid = t;
        return t;
    }
    case SPL_AST_TYPE_AGGREGATE:
        return sema_build_aggregate(sema, n, 0);
    case SPL_AST_TYPE_COMPTIME_CALL: {
        const char *name = n->type_comptime_call.name;
        if (name && strcmp(name, "self") == 0) {
            if (sema->current_aggregate_lang == 0) {
                SPL_ERROR(&n->dbg, "`@self` outside of aggregate");
                sema->error_count++;
                return 0;
            }
            n->resolved_lang_tid = sema->current_aggregate_lang;
            return sema->current_aggregate_lang;
        }
        return 0;
    }

    /* ---------- 顶层声明 ---------- */
    case SPL_AST_CONTAINER_MEMBERS:
        for (usize i = 0; i < vec_size(n->container_members.declarations); ++i)
            sema_infer(sema, vec_at(n->container_members.declarations, i));
        return 0;

    case SPL_AST_FN_DECL: {
        if (n->resolved_def_id == 0)
            Panic("fn `%s` not collected", n->fn_decl.name);

        spl_def_node_t *def = spl_def_node(sema->type, n->resolved_def_id);
        if (!def)
            return 0;

        spl_def_id_t owner_def_id = def->owner_def;
        spl_lang_type_id_t fn_tid = def->lang_id;
        if (fn_tid == 0)
            fn_tid = sema_eval_decl(sema, n->resolved_def_id);
        spl_lang_type_node_t *fn_ln = spl_lang_type_node(sema->type, fn_tid);
        if (!fn_ln || fn_ln->kind != SPL_LANG_TYPE_FN)
            return 0;
        spl_lang_type_id_t ret_tid = fn_ln->extra.fn.ret;

        if (!n->fn_decl.body)
            return fn_tid;

        spl_lang_type_id_t saved_agg = sema->current_aggregate_lang;
        if (owner_def_id) {
            spl_def_node_t *owner = spl_def_node(sema->type, owner_def_id);
            if (owner && owner->lang_id != 0)
                sema->current_aggregate_lang = owner->lang_id;
        }

        sema_push_scope(sema);
        for (usize i = 0; i < vec_size(n->fn_decl.params); ++i) {
            spl_ast_node_t *pd = spl_ast_node(sema->ast, vec_at(n->fn_decl.params, i));
            if (pd && pd->kind == SPL_AST_PARAM_DECL) {
                spl_symbol_t psym = {.name = pd->param_decl.name, .kind = SPL_SYMBOL_KIND_VAR};
                psym.node = spl_def_alloc(sema->type, SPL_DEF_VAR, psym.name, pd->dbg,
                                          vec_at(n->fn_decl.params, i));
                spl_lang_type_id_t p_tid = sema_infer(sema, pd->param_decl.type_expr);
                spl_def_node_t *pdef = spl_def_node(sema->type, psym.node);
                if (pdef) {
                    pdef->lang_id = p_tid;
                    pdef->state = p_tid ? SPL_DECL_RESOLVED : SPL_DECL_ERROR;
                }
                pd->resolved_def_id = psym.node;
                spl_scope_insert(sema->scope, sema->scope->current_scope, psym);
            }
        }
        spl_lang_type_id_t old_ret = sema->current_fn_ret_tid;
        sema->current_fn_ret_tid = ret_tid;
        sema_infer(sema, n->fn_decl.body);
        sema->current_fn_ret_tid = old_ret;
        sema_pop_scope(sema);

        sema->current_aggregate_lang = saved_agg;
        return fn_tid;
    }

    case SPL_AST_TYPE_DECL: {
        if (!n->type_decl.type_expr)
            break;
        spl_def_node_t *def =
            n->resolved_def_id ? spl_def_node(sema->type, n->resolved_def_id) : NULL;
        if (!def)
            break;
        spl_lang_type_id_t lang = def->lang_id;
        if (lang == 0)
            lang = sema_eval_decl(sema, n->resolved_def_id);
        if (lang == 0)
            break;

        spl_ast_node_t *te = spl_ast_node(sema->ast, n->type_decl.type_expr);
        if (te && te->kind == SPL_AST_TYPE_AGGREGATE) {
            for (usize i = 0; i < vec_size(te->type_aggregate.members); ++i) {
                spl_ast_node_ref_t mref = vec_at(te->type_aggregate.members, i);
                spl_ast_node_t *mn = spl_ast_node(sema->ast, mref);
                if (mn && mn->kind == SPL_AST_FN_DECL)
                    sema_infer(sema, mref);
            }
        }
        return lang;
    }

    /* ---------- VAR / CONST ---------- */
    case SPL_AST_VAR_DECL:
    case SPL_AST_CONST_DECL: {
        spl_ast_node_t *pat = spl_ast_node(sema->ast, n->var_const_decl.pattern);
        if (!pat || pat->kind != SPL_AST_PATTERN_IDENT) {
            SPL_ERROR(&n->dbg, "unsupported variable pattern");
            sema->error_count++;
            return 0;
        }
        const char *name = pat->pattern_ident.name;

        if (n->resolved_def_id == 0) {
            spl_symbol_t sym = {.name = name, .kind = SPL_SYMBOL_KIND_VAR};
            sym.node = spl_def_alloc(sema->type, SPL_DEF_VAR, name, n->dbg, ref);
            n->resolved_def_id = sym.node;
            spl_scope_insert(sema->scope, sema->scope->current_scope, sym);
        }

        spl_lang_type_id_t decl_tid = 0;
        if (n->var_const_decl.type)
            decl_tid = sema_infer(sema, n->var_const_decl.type);

        if (!n->var_const_decl.init_expr) {
            SPL_ERROR(&n->dbg, "variable `%s` must be initialized", name);
            sema->error_count++;
            return 0;
        }

        if (decl_tid) {
            sema_coerce(sema, n->var_const_decl.init_expr, decl_tid);
        } else {
            decl_tid = sema_infer(sema, n->var_const_decl.init_expr);
            if (!decl_tid || sema_is_infer(sema, decl_tid)) {
                SPL_ERROR(&n->dbg, "cannot infer type of `%s`", name);
                sema->error_count++;
                return 0;
            }
        }

        spl_def_resolve(sema->type, n->resolved_def_id, decl_tid);
        n->resolved_lang_tid = decl_tid;
        return decl_tid;
    }

    /* ---------- MEMBER / PARAM ---------- */
    case SPL_AST_MEMBER_DECL: {
        if (n->member_decl.type_expr)
            return sema_infer(sema, n->member_decl.type_expr);
        return 0;
    }
    case SPL_AST_PARAM_DECL: {
        if (n->param_decl.type_expr)
            return sema_infer(sema, n->param_decl.type_expr);
        return 0;
    }

    /* ---------- 语句 ---------- */
    case SPL_AST_STATEMENT_RET: {
        if (n->statement_ret.expr) {
            if (sema->current_fn_ret_tid)
                sema_coerce(sema, n->statement_ret.expr, sema->current_fn_ret_tid);
            else
                sema_infer(sema, n->statement_ret.expr);
        } else if (sema->current_fn_ret_tid) {
            spl_lang_type_id_t u = spl_lang_make_unit(sema->type);
            if (sema->current_fn_ret_tid != u) {
                SPL_ERROR(&n->dbg, "function must return a value");
                sema->error_count++;
            }
        }
        return 0;
    }
    case SPL_AST_STATEMENT_BREAK: {
        const char *lbl = NULL;
        if (n->statement_break.label) {
            spl_ast_node_t *ln = spl_ast_node(sema->ast, n->statement_break.label);
            if (ln && ln->kind == SPL_AST_LABEL)
                lbl = ln->label.name;
        }
        if (vec_size(sema->label_stack) == 0) {
            SPL_ERROR(&n->dbg, "`break` outside of loop");
            sema->error_count++;
            return 0;
        }
        if (lbl) {
            bool found = false;
            for (usize i = vec_size(sema->label_stack); i > 0; --i) {
                const char *cur = vec_at(sema->label_stack, i - 1);
                if (cur && strcmp(cur, lbl) == 0) {
                    found = true;
                    break;
                }
            }
            if (!found) {
                SPL_ERROR(&n->dbg, "undefined label `$%s`", lbl);
                sema->error_count++;
            }
        }
        if (n->statement_break.expr) {
            /* 有值 loop：break 值 coerce 到 loop 的期望类型 */
            if (sema->current_loop_break_tid != 0) {
                sema_coerce(sema, n->statement_break.expr, sema->current_loop_break_tid);
            } else {
                sema_infer(sema, n->statement_break.expr);
            }
        }
        return 0;
    }
    case SPL_AST_STATEMENT_CONTINUE: {
        const char *lbl = NULL;
        if (n->statement_continue.label) {
            spl_ast_node_t *ln = spl_ast_node(sema->ast, n->statement_continue.label);
            if (ln && ln->kind == SPL_AST_LABEL)
                lbl = ln->label.name;
        }
        if (vec_size(sema->label_stack) == 0) {
            SPL_ERROR(&n->dbg, "`continue` outside of loop");
            sema->error_count++;
            return 0;
        }
        if (lbl) {
            bool found = false;
            for (usize i = vec_size(sema->label_stack); i > 0; --i) {
                const char *cur = vec_at(sema->label_stack, i - 1);
                if (cur && strcmp(cur, lbl) == 0) {
                    found = true;
                    break;
                }
            }
            if (!found) {
                SPL_ERROR(&n->dbg, "undefined label `$%s`", lbl);
                sema->error_count++;
            }
        }
        return 0;
    }
    case SPL_AST_STATEMENT_DEFER:
        if (n->statement_defer.body)
            sema_infer(sema, n->statement_defer.body);
        return 0;
    case SPL_AST_STATEMENT_COMPTIME:
        if (n->statement_comptime.body)
            sema_infer(sema, n->statement_comptime.body);
        return 0;
    case SPL_AST_STATEMENT_DECL:
        if (n->statement_decl.decl)
            sema_infer(sema, n->statement_decl.decl);
        return 0;
    case SPL_AST_STATEMENT_EXPR:
        if (n->statement_expr.expr)
            sema_infer(sema, n->statement_expr.expr);
        return 0;

    case SPL_AST_TOP_LEVEL_BLOCK:
        if (n->top_level_block.block)
            sema_infer(sema, n->top_level_block.block);
        return 0;

    default:
        return 0;
    }
    return 0;
}

void spl_sema_init(spl_sema_t *sema, spl_ast_t *ast, spl_type_t *type, spl_scope_t *scope,
                   spl_attr_t *attr) {
    Assert(sema != NULL && ast != NULL && type != NULL && scope != NULL && attr != NULL);
    sema->ast = ast;
    sema->type = type;
    sema->scope = scope;
    sema->error_count = 0;
    sema->current_fn_ret_tid = 0;
    sema->current_aggregate_lang = 0;
    sema->current_loop_break_tid = 0;
    sema->attr = attr;
    sema->root = (spl_symbol_t){0};
    sema->store_scope = 0;
    vec_init(sema->label_stack);
}

void spl_sema_drop(spl_sema_t *sema) { vec_free(sema->label_stack); }

void spl_sema_run_module(spl_sema_t *sema, spl_ast_node_ref_t module_ref) {
    if (!sema->ast || !module_ref)
        return;
    spl_ast_node_t *mod = spl_ast_node(sema->ast, module_ref);
    if (!mod || mod->kind != SPL_AST_CONTAINER_MEMBERS)
        return;
    spl_scope_id_t saved = sema->scope->current_scope;
    sema_collect(sema, module_ref);
    sema_infer(sema, module_ref);
    sema->scope->current_scope = saved;
}

void spl_sema_run(spl_sema_t *sema) {
    if (!sema->ast || !sema->ast->root)
        return;
    spl_ast_node_t *root = spl_ast_node(sema->ast, sema->ast->root);
    if (!root || root->kind != SPL_AST_ROOT)
        return;
    spl_sema_run_module(sema, root->root.members);
}

void spl_sema_dump(spl_sema_t *sema) {
    printf("Scopes:\n");
    for (usize i = 1; i < vec_size(sema->scope->scopes); ++i) {
        spl_scope_node_t *scope = &vec_at(sema->scope->scopes, i);
        printf("scope[%zu] parent=%zu\n", i, scope->parent);
        map_for(scope->symbols, j) {
            spl_symbol_t *symbol = &unsafe_map_at(scope->symbols, j).val;
            printf("  %s -> def`%s`#%zu\n", unsafe_map_at(scope->symbols, j).key, symbol->name,
                   symbol->node);
        }
    }
    printf("LangTypeTable:\n");
    for (usize i = 1; i < vec_size(sema->type->lang_table); ++i) {
        printf("  lang_id#%zu ", i);
        spl_lang_type_dump(sema->type, i);
        printf("\n");
    }
    printf("TypeTable:\n");
    for (usize i = 1; i < vec_size(sema->type->type_table); ++i) {
        printf("  type_id#%zu ", i);
        spl_type_pure_dump(sema->type, i);
        printf("\n");
    }
    printf("DefTable:\n");
    for (usize i = 1; i < vec_size(sema->type->def_table); ++i) {
        printf("  def#%zu ", i);
        spl_type_def_dump(sema->type, i);
        printf("\n");
    }
    spl_attr_dump(sema->attr);
}