refactor(transformer): use ctx.var_declarations.create_var* methods (…

…#7666)

It turns out these APIs are very useful, we remove many boilerplate code.

crates/oxc_transformer/src/common/var_declarations.rs

@@ -101,7 +101,6 @@ impl<'a> VarDeclarationsStore<'a> {
     /// Create a new [`BoundIdentifier`], add a var declaration to be inserted at the top of
     /// the current enclosing statement block, and then return the [`BoundIdentifier`].
     #[inline]
-    #[expect(unused)]
     pub fn create_var(&self, name: &str, ctx: &mut TraverseCtx<'a>) -> BoundIdentifier<'a> {
         let binding = ctx.generate_uid_in_current_hoist_scope(name);
         self.insert_var(&binding, None, ctx);
@@ -112,7 +111,6 @@ impl<'a> VarDeclarationsStore<'a> {
     /// to be inserted at the top of the current enclosing statement block, and then return
     /// the [`BoundIdentifier`].
     #[inline]
-    #[expect(unused)]
     pub fn create_var_with_init(
         &self,
         name: &str,
@@ -127,7 +125,6 @@ impl<'a> VarDeclarationsStore<'a> {
     /// Create a new [`BoundIdentifier`] based on node, add a var declaration to be inserted
     /// at the top of the current enclosing statement block, and then return the [`BoundIdentifier`].
     #[inline]
-    #[expect(unused)]
     pub fn create_var_based_on_node<N: GatherNodeParts<'a>>(
         &self,
         node: &N,

crates/oxc_transformer/src/es2016/exponentiation_operator.rs

@@ -34,7 +34,7 @@
 
 use oxc_allocator::{CloneIn, Vec as ArenaVec};
 use oxc_ast::{ast::*, NONE};
-use oxc_semantic::{ReferenceFlags, SymbolFlags};
+use oxc_semantic::ReferenceFlags;
 use oxc_span::SPAN;
 use oxc_syntax::operator::{AssignmentOperator, BinaryOperator};
 use oxc_traverse::{BoundIdentifier, Traverse, TraverseCtx};
@@ -558,13 +558,8 @@ impl<'a, 'ctx> ExponentiationOperator<'a, 'ctx> {
         temp_var_inits: &mut ArenaVec<'a, Expression<'a>>,
         ctx: &mut TraverseCtx<'a>,
     ) -> BoundIdentifier<'a> {
-        let binding = ctx.generate_uid_in_current_scope_based_on_node(
-            &expr,
-            SymbolFlags::FunctionScopedVariable,
-        );
-
         // var _name;
-        self.ctx.var_declarations.insert_var(&binding, None, ctx);
+        let binding = self.ctx.var_declarations.create_var_based_on_node(&expr, ctx);
 
         // Add new reference `_name = name` to `temp_var_inits`
         temp_var_inits.push(ctx.ast.expression_assignment(

crates/oxc_transformer/src/es2020/optional_chaining.rs

@@ -51,7 +51,6 @@ use std::mem;
 
 use oxc_allocator::CloneIn;
 use oxc_ast::{ast::*, NONE};
-use oxc_semantic::SymbolFlags;
 use oxc_span::SPAN;
 use oxc_traverse::{Ancestor, BoundIdentifier, MaybeBoundIdentifier, Traverse, TraverseCtx};
 
@@ -296,18 +295,6 @@ impl<'a, 'ctx> OptionalChaining<'a, 'ctx> {
         }
     }
 
-    /// Generate a binding based on the node and insert the binding at the top of the current block
-    fn generate_binding(
-        &mut self,
-        expr: &Expression<'a>,
-        ctx: &mut TraverseCtx<'a>,
-    ) -> BoundIdentifier<'a> {
-        let binding = ctx
-            .generate_uid_in_current_scope_based_on_node(expr, SymbolFlags::FunctionScopedVariable);
-        self.ctx.var_declarations.insert_var(&binding, None, ctx);
-        binding
-    }
-
     /// Return `left = right`
     fn create_assignment_expression(
         left: AssignmentTarget<'a>,
@@ -409,7 +396,7 @@ impl<'a, 'ctx> OptionalChaining<'a, 'ctx> {
                     .create_read_expression(ctx)
             } else {
                 // `foo.bar` -> `_foo$bar = foo.bar`
-                let binding = self.generate_binding(object, ctx);
+                let binding = self.ctx.var_declarations.create_var_based_on_node(object, ctx);
                 *object = Self::create_assignment_expression(
                     binding.create_write_target(ctx),
                     ctx.ast.move_expression(object),
@@ -584,7 +571,7 @@ impl<'a, 'ctx> OptionalChaining<'a, 'ctx> {
         }
 
         // We should generate a temp binding for the expression first to avoid the next step changing the expression.
-        let temp_binding = self.generate_binding(expr, ctx);
+        let temp_binding = self.ctx.var_declarations.create_var_based_on_node(expr, ctx);
         if is_call && !self.ctx.assumptions.pure_getters {
             if let Some(member) = expr.as_member_expression_mut() {
                 let object = member.object_mut();
@@ -593,7 +580,8 @@ impl<'a, 'ctx> OptionalChaining<'a, 'ctx> {
                 if let Expression::Identifier(ident) = object {
                     let binding =
                         self.get_existing_binding_for_identifier(ident, ctx).unwrap_or_else(|| {
-                            let binding = self.generate_binding(object, ctx);
+                            let binding =
+                                self.ctx.var_declarations.create_var_based_on_node(object, ctx);
                             // `(_foo = foo)`
                             *object = Self::create_assignment_expression(
                                 binding.create_write_target(ctx),
@@ -650,7 +638,7 @@ impl<'a, 'ctx> OptionalChaining<'a, 'ctx> {
 
         let temp_binding = {
             if self.temp_binding.is_none() {
-                let binding = self.generate_binding(expr, ctx);
+                let binding = self.ctx.var_declarations.create_var_based_on_node(expr, ctx);
                 self.set_temp_binding(binding);
             }
             self.temp_binding.as_ref().unwrap()

crates/oxc_transformer/src/es2021/logical_assignment_operators.rs

@@ -56,7 +56,7 @@
 
 use oxc_allocator::CloneIn;
 use oxc_ast::ast::*;
-use oxc_semantic::{ReferenceFlags, SymbolFlags};
+use oxc_semantic::ReferenceFlags;
 use oxc_span::SPAN;
 use oxc_syntax::operator::{AssignmentOperator, LogicalOperator};
 use oxc_traverse::{BoundIdentifier, MaybeBoundIdentifier, Traverse, TraverseCtx};
@@ -310,12 +310,6 @@ impl<'a, 'ctx> LogicalAssignmentOperators<'a, 'ctx> {
         if ctx.is_static(expr) {
             return None;
         }
-
-        // var _name;
-        let binding = ctx
-            .generate_uid_in_current_scope_based_on_node(expr, SymbolFlags::FunctionScopedVariable);
-        self.ctx.var_declarations.insert_var(&binding, None, ctx);
-
-        Some(binding)
+        Some(self.ctx.var_declarations.create_var_based_on_node(expr, ctx))
     }
 }

crates/oxc_transformer/src/es2022/class_properties/private.rs

@@ -8,7 +8,7 @@ use oxc_ast::{ast::*, NONE};
 use oxc_span::SPAN;
 use oxc_syntax::{
     reference::{ReferenceFlags, ReferenceId},
-    symbol::{SymbolFlags, SymbolId},
+    symbol::SymbolId,
 };
 use oxc_traverse::{
     ast_operations::get_var_name_from_node, Ancestor, BoundIdentifier, MaybeBoundIdentifier,
@@ -676,10 +676,6 @@ impl<'a, 'ctx> ClassProperties<'a, 'ctx> {
         let prop_ident2 = prop_binding.create_read_expression(ctx);
 
         let temp_var_name_base = get_var_name_from_node(field_expr);
-        let temp_binding = ctx.generate_uid_in_current_scope(
-            &temp_var_name_base,
-            SymbolFlags::FunctionScopedVariable,
-        );
 
         // TODO(improve-on-babel): Could avoid `move_expression` here and replace `update_expr.argument` instead.
         // Only doing this first to match the order Babel creates temp vars.
@@ -739,7 +735,7 @@ impl<'a, 'ctx> ClassProperties<'a, 'ctx> {
             };
 
             // `_object$prop = _assertClassBrand(Class, object, _prop)._`
-            self.ctx.var_declarations.insert_var(&temp_binding, None, ctx);
+            let temp_binding = self.ctx.var_declarations.create_var(&temp_var_name_base, ctx);
             let assignment = create_assignment(&temp_binding, get_expr, ctx);
 
             // `++_object$prop` / `_object$prop++` (reusing existing `UpdateExpression`)
@@ -772,11 +768,7 @@ impl<'a, 'ctx> ClassProperties<'a, 'ctx> {
                 // Source = `object.#prop++` (postfix `++`)
 
                 // `_object$prop2 = _object$prop++`
-                let temp_binding2 = ctx.generate_uid_in_current_scope(
-                    &temp_var_name_base,
-                    SymbolFlags::FunctionScopedVariable,
-                );
-                self.ctx.var_declarations.insert_var(&temp_binding2, None, ctx);
+                let temp_binding2 = self.ctx.var_declarations.create_var(&temp_var_name_base, ctx);
                 let assignment2 = create_assignment(&temp_binding2, update_expr, ctx);
 
                 // `(_object$prop = _assertClassBrand(Class, object, _prop)._, _object$prop2 = _object$prop++, _object$prop)`
@@ -819,7 +811,7 @@ impl<'a, 'ctx> ClassProperties<'a, 'ctx> {
             let get_call = self.create_private_field_get(prop_ident, object2, SPAN, ctx);
 
             // `_object$prop = _classPrivateFieldGet(_prop, object)`
-            self.ctx.var_declarations.insert_var(&temp_binding, None, ctx);
+            let temp_binding = self.ctx.var_declarations.create_var(&temp_var_name_base, ctx);
             let assignment = create_assignment(&temp_binding, get_call, ctx);
 
             // `++_object$prop` / `_object$prop++` (reusing existing `UpdateExpression`)
@@ -839,11 +831,7 @@ impl<'a, 'ctx> ClassProperties<'a, 'ctx> {
             } else {
                 // Source = `object.#prop++` (postfix `++`)
                 // `_object$prop2 = _object$prop++`
-                let temp_binding2 = ctx.generate_uid_in_current_scope(
-                    &temp_var_name_base,
-                    SymbolFlags::FunctionScopedVariable,
-                );
-                self.ctx.var_declarations.insert_var(&temp_binding2, None, ctx);
+                let temp_binding2 = self.ctx.var_declarations.create_var(&temp_var_name_base, ctx);
                 let assignment2 = create_assignment(&temp_binding2, update_expr, ctx);
 
                 // `(_object$prop = _classPrivateFieldGet(_prop, object), _object$prop2 = _object$prop++, _object$prop)`
@@ -1131,11 +1119,7 @@ impl<'a, 'ctx> ClassProperties<'a, 'ctx> {
 
         // `A.B` -> `(_A$B = A.B) === null || _A$B === void 0`
         // TODO: should add an API `generate_uid_in_current_hoist_scope_based_on_node` to instead this
-        let temp_var_binding = ctx.generate_uid_in_current_scope_based_on_node(
-            object,
-            SymbolFlags::FunctionScopedVariable,
-        );
-        self.ctx.var_declarations.insert_var(&temp_var_binding, None, ctx);
+        let temp_var_binding = self.ctx.var_declarations.create_var_based_on_node(object, ctx);
 
         let object = mem::replace(object, temp_var_binding.create_read_expression(ctx));
         let assignment = create_assignment(
@@ -1521,21 +1505,16 @@ impl<'a, 'ctx> ClassProperties<'a, 'ctx> {
                 // Previously `x += 1` (`x` read + write), but moving to `_x = x` (`x` read only)
                 *reference.flags_mut() = ReferenceFlags::Read;
 
-                ctx.generate_uid_in_current_scope(&ident.name, SymbolFlags::FunctionScopedVariable)
+                self.ctx.var_declarations.create_var(&ident.name, ctx)
             }
             Expression::ThisExpression(this) => {
                 // Reading `this` cannot have side effects, so no need for temp var
                 let object1 = ctx.ast.expression_this(this.span);
                 return (object1, object);
             }
-            _ => ctx.generate_uid_in_current_scope_based_on_node(
-                &object,
-                SymbolFlags::FunctionScopedVariable,
-            ),
+            _ => self.ctx.var_declarations.create_var_based_on_node(&object, ctx),
         };
 
-        self.ctx.var_declarations.insert_var(&temp_var_binding, None, ctx);
-
         let object1 = create_assignment(&temp_var_binding, object, ctx);
         let object2 = temp_var_binding.create_read_expression(ctx);
 

crates/oxc_transformer/src/jsx/refresh.rs

@@ -582,7 +582,15 @@ impl<'a, 'ctx> ReactRefresh<'a, 'ctx> {
             arguments.push(function);
         }
 
-        let binding = ctx.generate_uid_in_current_hoist_scope("s");
+        // _s = refresh_sig();
+        let init = ctx.ast.expression_call(
+            SPAN,
+            self.refresh_sig.to_expression(ctx),
+            NONE,
+            ctx.ast.vec(),
+            false,
+        );
+        let binding = self.ctx.var_declarations.create_var_with_init("s", init, ctx);
 
         // _s();
         let call_expression = ctx.ast.statement_expression(
@@ -598,19 +606,6 @@ impl<'a, 'ctx> ReactRefresh<'a, 'ctx> {
 
         body.statements.insert(0, call_expression);
 
-        // _s = refresh_sig();
-        self.ctx.var_declarations.insert_var(
-            &binding,
-            Some(ctx.ast.expression_call(
-                SPAN,
-                self.refresh_sig.to_expression(ctx),
-                NONE,
-                ctx.ast.vec(),
-                false,
-            )),
-            ctx,
-        );
-
         // Following is the signature call expression, will be generated in call site.
         // _s(App, signature_key, false, function() { return [] });
         //                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ custom hooks only

tasks/coverage/snapshots/semantic_misc.snap

@@ -55,12 +55,6 @@ tasks/coverage/misc/pass/oxc-3948-1.ts
 semantic error: Bindings mismatch:
 after transform: ScopeId(0): ["BrowserWorkingCopyBackupTracker", "CancellationToken", "DisposableStore", "EditorPart", "EditorService", "IEditorGroupsService", "IEditorService", "IFilesConfigurationService", "IInstantiationService", "ILifecycleService", "ILogService", "IUntitledTextResourceEditorInput", "IWorkingCopyBackup", "IWorkingCopyBackupService", "IWorkingCopyEditorHandler", "IWorkingCopyEditorService", "IWorkingCopyService", "InMemoryTestWorkingCopyBackupService", "LifecyclePhase", "Schemas", "TestServiceAccessor", "TestWorkingCopy", "URI", "UntitledTextEditorInput", "VSBuffer", "_asyncToGenerator", "assert", "bufferToReadable", "createEditorPart", "ensureNoDisposablesAreLeakedInTestSuite", "isWindows", "registerTestResourceEditor", "timeout", "toResource", "toTypedWorkingCopyId", "toUntypedWorkingCopyId", "workbenchInstantiationService", "workbenchTeardown"]
 rebuilt        : ScopeId(0): ["BrowserWorkingCopyBackupTracker", "DisposableStore", "EditorService", "IEditorGroupsService", "IEditorService", "IFilesConfigurationService", "ILifecycleService", "ILogService", "IWorkingCopyBackupService", "IWorkingCopyEditorService", "IWorkingCopyService", "InMemoryTestWorkingCopyBackupService", "LifecyclePhase", "Schemas", "TestServiceAccessor", "TestWorkingCopy", "URI", "UntitledTextEditorInput", "VSBuffer", "_asyncToGenerator", "assert", "bufferToReadable", "createEditorPart", "ensureNoDisposablesAreLeakedInTestSuite", "isWindows", "registerTestResourceEditor", "timeout", "toResource", "toTypedWorkingCopyId", "toUntypedWorkingCopyId", "workbenchInstantiationService", "workbenchTeardown"]
-Bindings mismatch:
-after transform: ScopeId(13): ["_await$accessor$edito", "accessor", "untitled", "untitledTextEditor", "untitledTextModel", "workingCopyBackupService"]
-rebuilt        : ScopeId(20): ["_await$accessor$edito", "_untitledTextModel$te", "accessor", "untitled", "untitledTextEditor", "untitledTextModel", "workingCopyBackupService"]
-Bindings mismatch:
-after transform: ScopeId(14): ["_untitledTextModel$te"]
-rebuilt        : ScopeId(21): []
 Symbol reference IDs mismatch for "URI":
 after transform: SymbolId(1): [ReferenceId(109), ReferenceId(117), ReferenceId(156), ReferenceId(158), ReferenceId(160), ReferenceId(162)]
 rebuilt        : SymbolId(1): [ReferenceId(158), ReferenceId(160), ReferenceId(162), ReferenceId(164)]
@@ -103,9 +97,6 @@ rebuilt        : SymbolId(26): [ReferenceId(16)]
 Symbol reference IDs mismatch for "TestWorkingCopyBackupTracker":
 after transform: SymbolId(39): [ReferenceId(42), ReferenceId(74), ReferenceId(154), ReferenceId(215)]
 rebuilt        : SymbolId(34): [ReferenceId(65), ReferenceId(216)]
-Symbol scope ID mismatch for "_untitledTextModel$te":
-after transform: SymbolId(138): ScopeId(14)
-rebuilt        : SymbolId(63): ScopeId(20)
 Unresolved reference IDs mismatch for "Promise":
 after transform: [ReferenceId(36), ReferenceId(39), ReferenceId(82), ReferenceId(114), ReferenceId(153), ReferenceId(282)]
 rebuilt        : [ReferenceId(289)]

tasks/coverage/snapshots/semantic_test262.snap

@@ -2,7 +2,7 @@ commit: fd979d85
 
 semantic_test262 Summary:
 AST Parsed     : 44026/44026 (100.00%)
-Positive Passed: 43495/44026 (98.79%)
+Positive Passed: 43497/44026 (98.80%)
 tasks/coverage/test262/test/annexB/language/function-code/if-decl-else-decl-a-func-block-scoping.js
 semantic error: Symbol scope ID mismatch for "f":
 after transform: SymbolId(3): ScopeId(4294967294)
@@ -3740,43 +3740,6 @@ Unresolved references mismatch:
 after transform: ["$DONE", "Object", "assert", "require"]
 rebuilt        : ["$DONE", "Object", "_superprop_getMethod", "assert", "require"]
 
-tasks/coverage/test262/test/language/expressions/optional-chaining/iteration-statement-for-of-type-error.js
-semantic error: Bindings mismatch:
-after transform: ScopeId(1): []
-rebuilt        : ScopeId(1): ["_ref"]
-Bindings mismatch:
-after transform: ScopeId(2): ["_ref", "key"]
-rebuilt        : ScopeId(2): ["key"]
-Bindings mismatch:
-after transform: ScopeId(3): []
-rebuilt        : ScopeId(3): ["_ref2"]
-Bindings mismatch:
-after transform: ScopeId(4): ["_ref2", "key"]
-rebuilt        : ScopeId(4): ["key"]
-Symbol scope ID mismatch for "_ref":
-after transform: SymbolId(5): ScopeId(2)
-rebuilt        : SymbolId(0): ScopeId(1)
-Symbol scope ID mismatch for "_ref2":
-after transform: SymbolId(6): ScopeId(4)
-rebuilt        : SymbolId(2): ScopeId(3)
-
-tasks/coverage/test262/test/language/expressions/optional-chaining/iteration-statement-for.js
-semantic error: Bindings mismatch:
-after transform: ScopeId(0): ["count", "count2", "obj", "obj2", "obj3", "touched"]
-rebuilt        : ScopeId(0): ["_obj3$a", "_undefined", "count", "count2", "obj", "obj2", "obj3", "touched"]
-Bindings mismatch:
-after transform: ScopeId(5): ["_undefined"]
-rebuilt        : ScopeId(5): []
-Bindings mismatch:
-after transform: ScopeId(8): ["_obj3$a"]
-rebuilt        : ScopeId(8): []
-Symbol scope ID mismatch for "_undefined":
-after transform: SymbolId(6): ScopeId(5)
-rebuilt        : SymbolId(0): ScopeId(0)
-Symbol scope ID mismatch for "_obj3$a":
-after transform: SymbolId(7): ScopeId(8)
-rebuilt        : SymbolId(1): ScopeId(0)
-
 tasks/coverage/test262/test/language/module-code/top-level-await/syntax/for-await-await-expr-func-expression.js
 semantic error: Scope children mismatch:
 after transform: ScopeId(14): [ScopeId(1)]