fix(transformer): inline const enum members through type-cast wrappers

Wrapping a const enum access in `as T`, `satisfies T`, `!`, or `<T>`
prevented `optimizeConstEnums` from inlining it: the inliner's
`enter_expression` only matched bare `StaticMemberExpression` /
`ComputedMemberExpression`, while `annotations.rs` stripped the TS
wrapper after this hook returned — by which point the outer node had
been replaced and `enter_expression` was never re-invoked on it.

Peek through wrappers via `get_inner_expression_mut()` so the inner
member access is inlined; the outer replacement then drops the wrapper
along with the value.

Closes #22444

Author: Dunqing

crates/oxc_transformer/src/typescript/enum.rs

@@ -102,7 +102,11 @@ impl<'a> Traverse<'a, TransformState<'a>> for TypeScriptEnum {
             return;
         }
 
-        let inlined = match expr {
+        // Peek through TS-only wrappers and parens so `E.X as T`, `E.X satisfies T`,
+        // `E.X!`, `<T>E.X`, `E.X` (with `preserveParens`) all inline. `annotations.rs`
+        // strips these wrappers, but only after this hook returns — by then the outer
+        // node has been replaced and `enter_expression` is not re-invoked on it.
+        let inlined = match expr.get_inner_expression_mut() {
             Expression::StaticMemberExpression(member_expr) => {
                 self.try_inline_enum_member(member_expr, ctx)
             }

tasks/transform_conformance/snapshots/oxc.snap.md

@@ -1,6 +1,6 @@
 commit: 4079bcda
 
-Passed: 235/382
+Passed: 236/384
 
 # All Passed:
 * babel-plugin-transform-class-static-block
@@ -63,7 +63,7 @@ after transform: SymbolId(0): [ReferenceId(0), ReferenceId(2), ReferenceId(6), R
 rebuilt        : SymbolId(0): [ReferenceId(0), ReferenceId(2), ReferenceId(6), ReferenceId(10)]
 
 
-# babel-plugin-transform-typescript (22/56)
+# babel-plugin-transform-typescript (23/58)
 * allow-declare-fields-false/input.ts
 Unresolved references mismatch:
 after transform: ["dce"]
@@ -526,6 +526,20 @@ Symbol flags mismatch for "B":
 after transform: SymbolId(2): SymbolFlags(RegularEnum)
 rebuilt        : SymbolId(2): SymbolFlags(FunctionScopedVariable)
 
+* optimize-enums/type-cast/input.ts
+Bindings mismatch:
+after transform: ScopeId(1): ["Direction", "Down", "Up"]
+rebuilt        : ScopeId(1): ["Direction"]
+Scope flags mismatch:
+after transform: ScopeId(1): ScopeFlags(0x0)
+rebuilt        : ScopeId(1): ScopeFlags(Function)
+Symbol flags mismatch for "Direction":
+after transform: SymbolId(0): SymbolFlags(RegularEnum)
+rebuilt        : SymbolId(0): SymbolFlags(FunctionScopedVariable)
+Symbol reference IDs mismatch for "Direction":
+after transform: SymbolId(0): [ReferenceId(5), ReferenceId(1), ReferenceId(7), ReferenceId(3), ReferenceId(14)]
+rebuilt        : SymbolId(0): [ReferenceId(5)]
+
 * optimize-enums/typeof-kept/input.ts
 Bindings mismatch:
 after transform: ScopeId(1): ["Bar", "X"]

tasks/transform_conformance/tests/babel-plugin-transform-typescript/test/fixtures/const-enum-type-cast/input.ts

@@ -0,0 +1,29 @@
+const enum Phase {
+  idle,
+  active,
+}
+
+const enum Theme {
+  Light = "Light",
+  Dark = "Dark",
+}
+
+// `as` type-cast
+const a1 = Phase.idle as Phase;
+const a2 = Phase["active"] as Phase;
+const a3 = Theme.Light as Theme;
+
+// `satisfies` type-cast
+const s1 = Phase.idle satisfies Phase;
+const s2 = Theme.Dark satisfies Theme;
+
+// `!` non-null assertion
+const n1 = Phase.active!;
+const n2 = Theme.Light!;
+
+// `<T>` type assertion
+const t1 = <Phase>Phase.idle;
+
+// nested / combined
+const c1 = (Phase.active as Phase) satisfies Phase;
+const c2 = (Phase.idle satisfies Phase)!;

tasks/transform_conformance/tests/babel-plugin-transform-typescript/test/fixtures/const-enum-type-cast/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": [["transform-typescript", { "optimizeConstEnums": true }]]
+}

tasks/transform_conformance/tests/babel-plugin-transform-typescript/test/fixtures/const-enum-type-cast/output.js

@@ -0,0 +1,15 @@
+// `as` type-cast
+const a1 = 0;
+const a2 = 1;
+const a3 = "Light";
+// `satisfies` type-cast
+const s1 = 0;
+const s2 = "Dark";
+// `!` non-null assertion
+const n1 = 1;
+const n2 = "Light";
+// `<T>` type assertion
+const t1 = 0;
+// nested / combined
+const c1 = 1;
+const c2 = 0;

tasks/transform_conformance/tests/babel-plugin-transform-typescript/test/fixtures/optimize-enums/type-cast/input.ts

@@ -0,0 +1,10 @@
+enum Direction {
+  Up,
+  Down,
+}
+
+Direction.Up as Direction;
+Direction["Down"] as Direction;
+Direction.Up satisfies Direction;
+Direction.Down!;
+<Direction>Direction.Up;

tasks/transform_conformance/tests/babel-plugin-transform-typescript/test/fixtures/optimize-enums/type-cast/output.js

@@ -0,0 +1,10 @@
+var Direction = /* @__PURE__ */ function(Direction) {
+  Direction[Direction["Up"] = 0] = "Up";
+  Direction[Direction["Down"] = 1] = "Down";
+  return Direction;
+}(Direction || {});
+0;
+1;
+0;
+1;
+0;