feat: 泛型基础设施 — <T>解析 + 类型推断 (单态化 codegen 待补)

src/parser/parser.c

@@ -907,9 +907,22 @@ static AstNode* parse_function(Parser* p, bool is_pub, ErrorInfo* error) {
     const Token* fn_tok = advance(p);  // fn
     const Token* name = expect(p, TOK_IDENT, error, "fn 后应为函数名");
     if (!name) return NULL;
+    // 泛型类型参数: <T, U, ...>
+    const char* type_params[8]; int tp_count = 0;
+    if (peek(p)->kind == TOK_LT) {
+        advance(p);  // 跳过 '<'
+        while (peek(p)->kind != TOK_GT && !error->message) {
+            if (tp_count >= 8) { error->message = "类型参数过多 (最多8)"; error->filename = p->filename; error->line = peek(p)->line; error->col = peek(p)->col; return NULL; }
+            const Token* tp = expect(p, TOK_IDENT, error, "类型参数名");
+            if (!tp) return NULL;
+            type_params[tp_count++] = arena_strdup_impl(p->arena, tp->start, tp->length);
+            if (peek(p)->kind == TOK_COMMA) advance(p); else break;
+        }
+        if (!expect(p, TOK_GT, error, "缺少 '>'")) return NULL;
+    }
     if (!expect(p, TOK_LPAREN, error, "缺少 '('")) return NULL;
 
-    // 参数列表
+    // 参数列表（泛型参数可标注为类型参数名）
     AstNode* params[64]; int pcount = 0;
     while (peek(p)->kind != TOK_RPAREN && !error->message) {
         if (pcount >= 64) { error->message = "函数参数过多 (最多64)"; error->filename = p->filename; error->line = peek(p)->line; error->col = peek(p)->col; return NULL; }
@@ -941,9 +954,14 @@ static AstNode* parse_function(Parser* p, bool is_pub, ErrorInfo* error) {
 
     AstNode** parr = arena_alloc_impl(p->arena, pcount * sizeof(AstNode*));
     memcpy(parr, params, pcount * sizeof(AstNode*));
+    const char** tparr = NULL;
+    if (tp_count > 0) {
+        tparr = arena_alloc_impl(p->arena, tp_count * sizeof(const char*));
+        memcpy(tparr, type_params, tp_count * sizeof(const char*));
+    }
     return ast_make_function(p->arena,
         arena_strdup_impl(p->arena, name->start, name->length),
-        parr, pcount, ret, ret_struct_name, body, is_pub, tok_loc(fn_tok));
+        parr, pcount, ret, ret_struct_name, body, is_pub, tparr, tp_count, tok_loc(fn_tok));
 }
 
 // === 模块文件加载辅助 ===