chore(compiler): 清理过时 dead_code 标注与空代码块

crates/oxide_compiler/src/compiler.rs

@@ -310,7 +310,6 @@ impl CompileCtx {
         self.scopes.symbols.declare_initialized(name, reg, kind, is_const)
     }
 
-    #[allow(dead_code)]
     pub(crate) fn push_scope_with_kind(&mut self, kind: ScopeKind) {
         self.scopes.symbols.push_scope_with_kind(kind);
     }
@@ -507,7 +506,6 @@ impl Compiler {
         Self
     }
 
-    #[allow(dead_code)]
     pub(crate) fn analyze_upvalue_captures(
         &self, body_stmts: &[Statement], parent_ctx: &CompileCtx, nested_symbols: &SymbolTable,
     ) -> (Vec<UpvalueCapture>, u8) {
@@ -522,7 +520,6 @@ impl Compiler {
         (captures, count)
     }
 
-    #[allow(dead_code)]
     fn collect_upvalue_stmt(
         &self, stmt: &Statement, parent_ctx: &CompileCtx, nested_symbols: &SymbolTable,
         captures: &mut Vec<UpvalueCapture>, seen: &mut HashMap<String, usize>,
@@ -607,7 +604,6 @@ impl Compiler {
         }
     }
 
-    #[allow(dead_code)]
     fn collect_upvalue_expr(
         &self, expr: &Expression, parent_ctx: &CompileCtx, nested_symbols: &SymbolTable,
         captures: &mut Vec<UpvalueCapture>, seen: &mut HashMap<String, usize>,

crates/oxide_compiler/src/emit_ctx.rs

@@ -15,7 +15,6 @@ pub(crate) struct LabelCtx {
     /// label id → 指令下标。id 连续递增，Vec 索引即 id；写入前须扩容。
     pub(crate) label_pos: Vec<Option<usize>>,
     pub(crate) loop_stack: Vec<(LabelId, LabelId)>,
-    #[allow(dead_code)]
     pub(crate) switch_stack: Vec<LabelId>,
     /// Active labeled-statement scopes (resolves `break label` / `continue label`).
     pub(crate) label_scopes: Vec<LabelScope>,

crates/oxide_compiler/src/ir/lower.rs

@@ -13,10 +13,6 @@ use super::IRFunction;
 
 /// IRFunction → CompiledModule。错误消息与现状（退役前 compiler.rs）逐字一致。
 pub fn lower(f: &IRFunction) -> Result<CompiledModule, String> {
-    if f.reg_overflow || f.const_overflow {
-        // 溢出标志在下方统一检查；先做结构验证
-    }
-
     // 溢出检查 1：寄存器（仅 Operand::Reg 变体；This/NewTarget 是语义操作数，映射 254/255 合法）
     if f.reg_overflow {
         return Err("RangeError: function body uses too many registers (max 253)".into());