feat: 枚举 enum (P1 #7)

- lexer: TOK_ENUM, TOK_COLON_COLON
- ast: AST_ENUM_DECL, AST_ENUM_VARIANT + AST_PROGRAM enums数组
- parser: enum Name { A, B } + Enum::Variant语法
- sema: SYM_ENUM, 变体验证, enum→i64类型兼容
- codegen: TYPE_ENUM→i64, 变体→ConstInt(索引值)
- 新增集成测试: 17_enum.l

测试: 121 通过 (41+15+47+18)

src/ast/ast.c

@@ -10,7 +10,8 @@
 
 AstNode* ast_make_program(void* alloc, AstNode** fns, size_t fn_count,
                           AstNode** structs, size_t struct_count,
-                          AstNode** aliases, size_t alias_count, SourceLoc loc) {
+                          AstNode** aliases, size_t alias_count,
+                          AstNode** enums, size_t enum_count, SourceLoc loc) {
     NEW(alloc, AST_PROGRAM);
     n->as.program.functions = fns;
     n->as.program.fn_count = fn_count;
@@ -18,6 +19,8 @@ AstNode* ast_make_program(void* alloc, AstNode** fns, size_t fn_count,
     n->as.program.struct_count = struct_count;
     n->as.program.type_aliases = aliases;
     n->as.program.alias_count = alias_count;
+    n->as.program.enums = enums;
+    n->as.program.enum_count = enum_count;
     return n;
 }
 
@@ -177,3 +180,23 @@ AstNode* ast_make_type_alias(void* alloc, const char* name, TypeKind aliased,
     n->as.type_alias.aliased_struct_name = aliased_struct;
     return n;
 }
+
+// === 枚举相关工厂函数 ===
+
+AstNode* ast_make_enum_decl(void* alloc, const char* name, const char** variants,
+                              size_t count, SourceLoc loc) {
+    NEW(alloc, AST_ENUM_DECL);
+    n->as.enum_decl.name = name;
+    n->as.enum_decl.variants = variants;
+    n->as.enum_decl.variant_count = count;
+    return n;
+}
+
+AstNode* ast_make_enum_variant(void* alloc, const char* enum_name,
+                                 const char* variant_name, SourceLoc loc) {
+    NEW(alloc, AST_ENUM_VARIANT);
+    n->as.enum_variant.enum_name = enum_name;
+    n->as.enum_variant.variant_name = variant_name;
+    n->as.enum_variant.variant_index = -1;
+    return n;
+}

src/ast/ast.h

@@ -24,6 +24,8 @@ typedef enum {
     AST_STRUCT_INIT,      // Point { x: 10, y: 20 }
     AST_FIELD_ACCESS,     // p.x
     AST_TYPE_ALIAS,       // type Meters = i64
+    AST_ENUM_DECL,        // enum Color { Red, Green, Blue }
+    AST_ENUM_VARIANT,     // Color::Red
 } AstKind;
 
 typedef enum {
@@ -50,7 +52,8 @@ struct AstNode {
         // AST_PROGRAM
         struct { struct AstNode** functions; size_t fn_count;
                  struct AstNode** structs;   size_t struct_count;
-                 struct AstNode** type_aliases; size_t alias_count; } program;
+                 struct AstNode** type_aliases; size_t alias_count;
+                 struct AstNode** enums;     size_t enum_count; } program;
         // AST_FUNCTION
         struct { const char* name; struct AstNode** params; size_t param_count;
                  TypeKind return_type; const char* return_struct_type_name;
@@ -91,13 +94,18 @@ struct AstNode {
         struct { struct AstNode* object; const char* field; int field_index; } field_access;
         // AST_TYPE_ALIAS
         struct { const char* name; TypeKind aliased_type; const char* aliased_struct_name; } type_alias;
+        // AST_ENUM_DECL
+        struct { const char* name; const char** variants; size_t variant_count; } enum_decl;
+        // AST_ENUM_VARIANT
+        struct { const char* enum_name; const char* variant_name; int variant_index; } enum_variant;
     } as;
 };
 
 // 创建节点的辅助函数（内存来自 arena，通过 void* 传递避免循环依赖）
 AstNode* ast_make_program(void* alloc, AstNode** fns, size_t fn_count,
                           AstNode** structs, size_t struct_count,
-                          AstNode** aliases, size_t alias_count, SourceLoc loc);
+                          AstNode** aliases, size_t alias_count,
+                          AstNode** enums, size_t enum_count, SourceLoc loc);
 AstNode* ast_make_function(void* alloc, const char* name, AstNode** params, size_t pcount,
                            TypeKind ret, const char* ret_struct_name, AstNode* body, SourceLoc loc);
 AstNode* ast_make_parameter(void* alloc, const char* name, TypeKind type, const char* struct_type_name, SourceLoc loc);
@@ -122,5 +130,7 @@ AstNode* ast_make_struct_init(void* alloc, const char* type_name, const char** f
 AstNode* ast_make_field_access(void* alloc, AstNode* object, const char* field, SourceLoc loc);
 AstNode* ast_make_type_alias(void* alloc, const char* name, TypeKind aliased,
                               const char* aliased_struct, SourceLoc loc);
+AstNode* ast_make_enum_decl(void* alloc, const char* name, const char** variants, size_t count, SourceLoc loc);
+AstNode* ast_make_enum_variant(void* alloc, const char* enum_name, const char* variant_name, SourceLoc loc);
 
 #endif

src/codegen/codegen.c

@@ -63,6 +63,7 @@ static LLVMTypeRef to_llvm_type(CgCtx* ctx, TypeKind kind) {
         case TYPE_BOOL: return LLVMInt1TypeInContext(ctx->context);
         case TYPE_STR:  return LLVMPointerType(LLVMInt8TypeInContext(ctx->context), 0);
         case TYPE_STRUCT:
+        case TYPE_ENUM:  return LLVMInt64TypeInContext(ctx->context);
         case TYPE_UNKNOWN:
         case TYPE_ERROR:
         default:        return LLVMVoidTypeInContext(ctx->context);
@@ -347,6 +348,10 @@ static LLVMValueRef codegen_expr(CgCtx* ctx, AstNode* node) {
         return LLVMBuildLoad2(ctx->builder, struct_ty, alloca, "struct_val");
     }
 
+    case AST_ENUM_VARIANT:
+        return LLVMConstInt(LLVMInt64TypeInContext(ctx->context),
+            (unsigned long long)node->as.enum_variant.variant_index, true);
+
     default:
         return NULL;
     }

src/lexer/lexer.c

@@ -63,6 +63,7 @@ static TokenKind check_keyword(const Token* tok) {
     KW("bool",   TOK_BOOL);   KW("str",    TOK_STR);
     KW("void",   TOK_VOID);
     KW("struct", TOK_STRUCT); KW("type", TOK_TYPE);
+    KW("enum", TOK_ENUM);
     KW("true",   TOK_TRUE);   KW("false",  TOK_FALSE);
     #undef KW
     return TOK_IDENT;
@@ -141,6 +142,7 @@ Token* lex(Arena* a, const char* source, const char* filename,
         else if (c == '{') { tokens[idx++] = make_token(&l, TOK_LBRACE, l.pos, 1); advance(&l); }
         else if (c == '}') { tokens[idx++] = make_token(&l, TOK_RBRACE, l.pos, 1); advance(&l); }
         else if (c == ',') { tokens[idx++] = make_token(&l, TOK_COMMA, l.pos, 1); advance(&l); }
+        else if (c == ':' && peek_next(&l) == ':') { tokens[idx++] = make_token(&l, TOK_COLON_COLON, l.pos, 2); advance(&l); advance(&l); }
         else if (c == ':') { tokens[idx++] = make_token(&l, TOK_COLON, l.pos, 1); advance(&l); }
         else if (c == ';') { tokens[idx++] = make_token(&l, TOK_SEMICOLON, l.pos, 1); advance(&l); }
         else {

src/lexer/token.c

@@ -7,7 +7,7 @@
 static const char* NAMES[] = {
     [TOK_FN] = "fn", [TOK_LET] = "let", [TOK_MUT] = "mut", [TOK_IF] = "if",
     [TOK_ELSE] = "else", [TOK_WHILE] = "while", [TOK_FOR] = "for", [TOK_IN] = "in", [TOK_RETURN] = "return",
-    [TOK_STRUCT] = "struct", [TOK_TYPE] = "type",
+    [TOK_STRUCT] = "struct", [TOK_TYPE] = "type", [TOK_ENUM] = "enum",
     [TOK_I64] = "i64", [TOK_F64] = "f64", [TOK_BOOL] = "bool", [TOK_STR] = "str", [TOK_VOID] = "void",
     [TOK_INT_LIT] = "整数", [TOK_FLOAT_LIT] = "浮点数", [TOK_STR_LIT] = "字符串",
     [TOK_TRUE] = "true", [TOK_FALSE] = "false",
@@ -23,7 +23,7 @@ static const char* NAMES[] = {
     [TOK_LBRACE] = "{", [TOK_RBRACE] = "}",
     [TOK_COMMA] = ",", [TOK_COLON] = ":", [TOK_SEMICOLON] = ";",
     [TOK_ASSIGN] = "=",
-    [TOK_DOT] = ".",
+    [TOK_DOT] = ".", [TOK_COLON_COLON] = "::",
     [TOK_EOF] = "EOF", [TOK_ERROR] = "错误",
 };
 

src/lexer/token.h

@@ -7,7 +7,7 @@
 typedef enum {
     // 关键字
     TOK_FN, TOK_LET, TOK_MUT, TOK_IF, TOK_ELSE, TOK_WHILE, TOK_FOR, TOK_IN, TOK_RETURN,
-    TOK_STRUCT, TOK_TYPE,
+    TOK_STRUCT, TOK_TYPE, TOK_ENUM,
     // 类型关键字
     TOK_I64, TOK_F64, TOK_BOOL, TOK_STR, TOK_VOID,
     // 字面量
@@ -24,7 +24,7 @@ typedef enum {
     TOK_LPAREN, TOK_RPAREN, TOK_LBRACE, TOK_RBRACE,
     TOK_COMMA, TOK_COLON, TOK_SEMICOLON, TOK_ASSIGN,
     // 特殊
-    TOK_DOT,
+    TOK_DOT, TOK_COLON_COLON,
     TOK_EOF, TOK_ERROR,
 } TokenKind;
 

src/parser/parser.c

@@ -144,6 +144,17 @@ static AstNode* parse_struct_init(Parser* p, const Token* name, ErrorInfo* error
 static AstNode* parse_ident_or_call(Parser* p, ErrorInfo* error) {
     const Token* name = advance(p);
 
+    // 枚举变体引用: Name::Variant
+    if (peek(p)->kind == TOK_COLON_COLON) {
+        advance(p); // 跳过 ::
+        const Token* variant = expect(p, TOK_IDENT, error, "枚举变体名");
+        if (!variant) return NULL;
+        return ast_make_enum_variant(p->arena,
+            arena_strdup_impl(p->arena, name->start, name->length),
+            arena_strdup_impl(p->arena, variant->start, variant->length),
+            tok_loc(name));
+    }
+
     // 结构体初始化: Name { field: val, ... }
     // 用提前看来区别 struct init 和 block：
     // struct init → { IDENT COLON ... ；block → { 可能是 let/if/while/...
@@ -553,6 +564,7 @@ AstNode* parse(Arena* a, const Token* tokens, size_t count,
     AstNode* functions[256]; int fn_count = 0;
     AstNode* structs[64];   int struct_count = 0;
     AstNode* aliases[64];   int alias_count = 0;
+    AstNode* enums[64];     int enum_count = 0;
     while (peek(&p)->kind != TOK_EOF && !error->message) {
         if (peek(&p)->kind == TOK_STRUCT) {
             if (struct_count >= 64) { error->message = "结构体过多 (最多64)"; error->filename = p.filename; error->line = peek(&p)->line; error->col = peek(&p)->col; return NULL; }
@@ -569,11 +581,30 @@ AstNode* parse(Arena* a, const Token* tokens, size_t count,
             aliases[alias_count++] = ast_make_type_alias(a,
                 arena_strdup_impl(a, alias_name->start, alias_name->length),
                 rti.kind, rti.struct_name, tok_loc(type_tok));
+        } else if (peek(&p)->kind == TOK_ENUM) {
+            advance(&p);
+            const Token* name = expect(&p, TOK_IDENT, error, "enum 后应为枚举名");
+            if (!name) return NULL;
+            if (!expect(&p, TOK_LBRACE, error, "缺少 '{'")) return NULL;
+            const char* variants[64]; int vcount = 0;
+            while (peek(&p)->kind != TOK_RBRACE && !error->message) {
+                if (vcount >= 64) { error->message = "枚举变体过多(最多64)"; error->filename = p.filename; error->line = peek(&p)->line; error->col = peek(&p)->col; return NULL; }
+                const Token* vname = expect(&p, TOK_IDENT, error, "变体名");
+                if (!vname) return NULL;
+                variants[vcount++] = arena_strdup_impl(p.arena, vname->start, vname->length);
+                if (peek(&p)->kind == TOK_COMMA) advance(&p); else break;
+            }
+            if (!expect(&p, TOK_RBRACE, error, "缺少 '}'")) return NULL;
+            const char** v_arr = arena_alloc_impl(p.arena, vcount * sizeof(const char*));
+            memcpy(v_arr, variants, vcount * sizeof(const char*));
+            AstNode* enum_decl = ast_make_enum_decl(p.arena, arena_strdup_impl(p.arena, name->start, name->length), v_arr, vcount, tok_loc(name));
+            if (enum_count >= 64) { error->message = "枚举过多 (最多64)"; error->filename = p.filename; error->line = peek(&p)->line; error->col = peek(&p)->col; return NULL; }
+            enums[enum_count++] = enum_decl;
         } else if (peek(&p)->kind == TOK_FN) {
             if (fn_count >= 256) { error->message = "函数过多 (最多256)"; error->filename = p.filename; error->line = peek(&p)->line; error->col = peek(&p)->col; return NULL; }
             functions[fn_count++] = parse_function(&p, error);
         } else {
-            error->message = "顶层只允许 fn、struct 或 type";
+            error->message = "顶层只允许 fn、struct、type 或 enum";
             error->filename = p.filename;
             error->line = peek(&p)->line;
             error->col = peek(&p)->col;
@@ -587,6 +618,8 @@ AstNode* parse(Arena* a, const Token* tokens, size_t count,
     memcpy(st_arr, structs, struct_count * sizeof(AstNode*));
     AstNode** al_arr = arena_alloc_impl(a, alias_count * sizeof(AstNode*));
     memcpy(al_arr, aliases, alias_count * sizeof(AstNode*));
+    AstNode** en_arr = arena_alloc_impl(a, enum_count * sizeof(AstNode*));
+    memcpy(en_arr, enums, enum_count * sizeof(AstNode*));
     return ast_make_program(a, fn_arr, fn_count, st_arr, struct_count,
-                            al_arr, alias_count, loc_at(0, 0));
+                            al_arr, alias_count, en_arr, enum_count, loc_at(0, 0));
 }

src/sema/sema.c

@@ -6,14 +6,22 @@ static TypeKind current_return_type = TYPE_VOID;
 static const char* current_return_struct_name = NULL;
 
 static TypeKind promote(TypeKind a, TypeKind b) {
+    // 枚举在算术运算中视为 i64
+    if (a == TYPE_ENUM) a = TYPE_I64;
+    if (b == TYPE_ENUM) b = TYPE_I64;
     if (a == TYPE_F64 || b == TYPE_F64) return TYPE_F64;
     if (a == TYPE_I64 || b == TYPE_I64) return TYPE_I64;
     if (a == TYPE_BOOL || b == TYPE_BOOL) return TYPE_BOOL;
     return TYPE_ERROR;
 }
 
-static bool is_numeric(TypeKind t) { return t == TYPE_I64 || t == TYPE_F64; }
-static bool is_comparable(TypeKind a, TypeKind b) { return a == b; }
+static bool is_numeric(TypeKind t) { return t == TYPE_I64 || t == TYPE_F64 || t == TYPE_ENUM; }
+static bool is_comparable(TypeKind a, TypeKind b) {
+    if (a == b) return true;
+    // 枚举可以参与整数比较
+    if ((a == TYPE_I64 && b == TYPE_ENUM) || (a == TYPE_ENUM && b == TYPE_I64)) return true;
+    return false;
+}
 
 // === 向前声明 ===
 static void analyze_node(AstNode* node, Scope* scope, ErrorList* errors, Arena* a);
@@ -169,7 +177,8 @@ static void analyze_expr(AstNode* node, Scope* scope, ErrorList* errors, Arena*
                                   expected_name ? expected_name : "struct",
                                   actual_name ? actual_name : type_name(actual));
                     }
-                } else if (actual != expected) {
+                } else if (actual != expected &&
+                           !(expected == TYPE_I64 && actual == TYPE_ENUM)) {
                     error_add(errors, "<sema>", node->loc.line, node->loc.col,
                               "参数 %zu 类型不匹配: 期望 '%s'，得到 '%s'",
                               i + 1, type_name(expected), type_name(actual));
@@ -287,6 +296,26 @@ static void analyze_expr(AstNode* node, Scope* scope, ErrorList* errors, Arena*
         break;
     }
 
+    case AST_ENUM_VARIANT: {
+        Symbol* enum_sym = scope_lookup_struct(scope, node->as.enum_variant.enum_name);
+        if (!enum_sym || enum_sym->kind != SYM_ENUM) {
+            error_add(errors, "<sema>", node->loc.line, node->loc.col,
+                      "未定义的枚举 '%s'", node->as.enum_variant.enum_name);
+            node->type.kind = TYPE_ERROR; break;
+        }
+        int vi = scope_enum_variant_index(enum_sym, node->as.enum_variant.variant_name);
+        if (vi < 0) {
+            error_add(errors, "<sema>", node->loc.line, node->loc.col,
+                      "枚举 '%s' 没有变体 '%s'",
+                      node->as.enum_variant.enum_name,
+                      node->as.enum_variant.variant_name);
+            node->type.kind = TYPE_ERROR; break;
+        }
+        node->as.enum_variant.variant_index = vi;
+        node->type.kind = TYPE_ENUM;
+        break;
+    }
+
     default: break;
     }
 }
@@ -308,6 +337,13 @@ static void analyze_node(AstNode* node, Scope* scope, ErrorList* errors, Arena*
                 }
             }
         }
+        // 注册枚举
+        for (size_t i = 0; i < node->as.program.enum_count; i++) {
+            AstNode* ed = node->as.program.enums[i];
+            scope_insert_enum(scope, a, ed->as.enum_decl.name,
+                              ed->as.enum_decl.variants,
+                              ed->as.enum_decl.variant_count);
+        }
         // 第一遍：收集所有结构体定义
         for (size_t i = 0; i < node->as.program.struct_count; i++) {
             AstNode* sd = node->as.program.structs[i];
@@ -548,7 +584,8 @@ static void analyze_node(AstNode* node, Scope* scope, ErrorList* errors, Arena*
                                   expected_name ? expected_name : "struct",
                                   actual_name ? actual_name : type_name(actual));
                     }
-                } else if (actual != expected) {
+                } else if (actual != expected &&
+                           !(expected == TYPE_I64 && actual == TYPE_ENUM)) {
                     error_add(errors, "<sema>", node->loc.line, node->loc.col,
                               "返回类型不匹配: 期望 '%s'，得到 '%s'",
                               type_name(expected), type_name(actual));

src/sema/symbol.c

@@ -94,7 +94,7 @@ Symbol* scope_insert_struct(Scope* scope, void* alloc, const char* name,
 Symbol* scope_lookup_struct(const Scope* scope, const char* name) {
     for (const Scope* s = scope; s; s = s->parent) {
         for (Symbol* sym = s->head; sym; sym = sym->next) {
-            if (sym->kind == SYM_STRUCT && strcmp(sym->name, name) == 0)
+            if ((sym->kind == SYM_STRUCT || sym->kind == SYM_ENUM) && strcmp(sym->name, name) == 0)
                 return sym;
         }
     }
@@ -109,3 +109,35 @@ int scope_struct_field_index(const Symbol* sym, const char* field_name) {
     }
     return -1;
 }
+
+Symbol* scope_insert_enum(Scope* scope, void* alloc, const char* name,
+                           const char** vnames, size_t vc) {
+    if (scope->head) {
+        for (Symbol* sym = scope->head; sym; sym = sym->next) {
+            if (strcmp(sym->name, name) == 0) return NULL;
+        }
+    }
+    Symbol* sym = (Symbol*)arena_alloc_impl(alloc, sizeof(Symbol));
+    if (!sym) return NULL;
+    sym->name = name; sym->kind = SYM_ENUM; sym->type = TYPE_ENUM;
+    sym->is_mut = false; sym->return_type = TYPE_VOID;
+    sym->param_types = NULL; sym->param_count = 0;
+    sym->struct_field_names = vnames;
+    sym->struct_field_types = NULL;
+    sym->struct_field_struct_names = NULL;
+    sym->struct_field_count = vc;
+    sym->struct_type_name = NULL;
+    sym->is_type_alias = false;
+    sym->next = scope->head;
+    scope->head = sym;
+    return sym;
+}
+
+int scope_enum_variant_index(const Symbol* sym, const char* variant_name) {
+    if (sym->kind != SYM_ENUM) return -1;
+    for (size_t i = 0; i < sym->struct_field_count; i++) {
+        if (strcmp(sym->struct_field_names[i], variant_name) == 0)
+            return (int)i;
+    }
+    return -1;
+}

src/sema/symbol.h

@@ -4,7 +4,7 @@
 #include "l_lang.h"
 #include "ast.h"
 
-typedef enum { SYM_VARIABLE, SYM_PARAMETER, SYM_FUNCTION, SYM_STRUCT } SymbolKind;
+typedef enum { SYM_VARIABLE, SYM_PARAMETER, SYM_FUNCTION, SYM_STRUCT, SYM_ENUM } SymbolKind;
 
 typedef struct Symbol {
     const char* name;
@@ -61,4 +61,11 @@ Symbol* scope_lookup_struct(const Scope* scope, const char* name);
 // 在结构体符号中查找字段索引（返回 -1 表示未找到）
 int scope_struct_field_index(const Symbol* sym, const char* field_name);
 
+// 插入枚举符号
+Symbol* scope_insert_enum(Scope* scope, void* alloc, const char* name,
+                           const char** vnames, size_t vc);
+
+// 在枚举符号中查找变体索引（返回 -1 表示未找到）
+int scope_enum_variant_index(const Symbol* sym, const char* variant_name);
+
 #endif