feat: gate using declarations behind experimental feature flag

Signed-off-by: Abhinav Sharma <abhinavs1920bpl@gmail.com>

Author: abhinavs1920

core/engine/src/bytecompiler/mod.rs

@@ -2260,8 +2260,14 @@ impl<'ctx> ByteCompiler<'ctx> {
                             }
 
                             // Add resource to disposal stack
+                            #[cfg(feature = "experimental")]
                             self.bytecode.emit_add_disposable_resource(value.variable());
 
+                            #[cfg(not(feature = "experimental"))]
+                            self.emit_type_error(
+                                "using declarations require the 'experimental' feature",
+                            );
+
                             self.emit_binding(BindingOpcode::InitLexical, ident, &value);
                             self.register_allocator.dealloc(value);
                         }
@@ -2275,8 +2281,14 @@ impl<'ctx> ByteCompiler<'ctx> {
                             }
 
                             // Add resource to disposal stack
+                            #[cfg(feature = "experimental")]
                             self.bytecode.emit_add_disposable_resource(value.variable());
 
+                            #[cfg(not(feature = "experimental"))]
+                            self.emit_type_error(
+                                "using declarations require the 'experimental' feature",
+                            );
+
                             self.compile_declaration_pattern(
                                 pattern,
                                 BindingOpcode::InitLexical,
@@ -2300,9 +2312,11 @@ impl<'ctx> ByteCompiler<'ctx> {
                                 self.bytecode.emit_store_undefined(value.variable());
                             }
 
-                            // TODO: Add resource to async disposal stack
-                            // For now, we just bind the variable like a let declaration
-                            // Full implementation will add: AddAsyncDisposableResource opcode
+                            // await using is not yet implemented even under experimental
+                            #[cfg(not(feature = "experimental"))]
+                            self.emit_type_error(
+                                "await using declarations require the 'experimental' feature",
+                            );
 
                             self.emit_binding(BindingOpcode::InitLexical, ident, &value);
                             self.register_allocator.dealloc(value);
@@ -2316,7 +2330,12 @@ impl<'ctx> ByteCompiler<'ctx> {
                                 self.bytecode.emit_store_undefined(value.variable());
                             }
 
-                            // TODO: SAME
+                            // await using is not yet implemented even under experimental
+                            #[cfg(not(feature = "experimental"))]
+                            self.emit_type_error(
+                                "await using declarations require the 'experimental' feature",
+                            );
+
                             self.compile_declaration_pattern(
                                 pattern,
                                 BindingOpcode::InitLexical,

core/engine/src/bytecompiler/statement/block.rs

@@ -1,9 +1,10 @@
 use crate::bytecompiler::ByteCompiler;
+#[cfg(feature = "experimental")]
 use boa_ast::{
     declaration::LexicalDeclaration,
     operations::{LexicallyScopedDeclaration, lexically_scoped_declarations},
-    statement::Block,
 };
+use boa_ast::statement::Block;
 
 impl ByteCompiler<'_> {
     /// Compile a [`Block`] `boa_ast` node
@@ -12,6 +13,7 @@ impl ByteCompiler<'_> {
         self.block_declaration_instantiation(block);
 
         // Count how many `using` bindings are in this block (statically known at compile time)
+        #[cfg(feature = "experimental")]
         let using_count: u32 = lexically_scoped_declarations(block)
             .iter()
             .filter_map(|decl| {
@@ -29,6 +31,7 @@ impl ByteCompiler<'_> {
         self.compile_statement_list(block.statement_list(), use_expr, true);
 
         // Emit DisposeResources with the static count if there are any using declarations
+        #[cfg(feature = "experimental")]
         if using_count > 0 {
             self.bytecode.emit_dispose_resources(using_count.into());
         }