More aggressively inline decorators in the static block

babel.config.js

@@ -543,7 +543,6 @@ function pluginToggleBooleanFlag({ types: t }, { name, value }) {
       if (left.value === false) return res.replace(right.replacement);
       if (right.value === false) return res.replace(left.replacement);
       if (left.unrelated && right.unrelated) return res.unrelated();
-      console.log(left, right);
       return res.replace(
         t.logicalExpression("||", left.replacement, right.replacement)
       );

packages/babel-helper-create-class-features-plugin/src/decorators.ts

@@ -751,6 +751,32 @@ function createPrivateBrandCheckClosure(brandName: t.PrivateName) {
   );
 }
 
+// Check if the expression does not reference function-specific
+// context or the given identifier name.
+// `true` means "maybe" and `false` means "no".
+function usesFunctionContextOrRef(
+  expression: t.Node,
+  refName: string | undefined,
+) {
+  try {
+    t.traverseFast(expression, node => {
+      if (
+        t.isThisExpression(node) ||
+        t.isSuper(node) ||
+        t.isIdentifier(node, { name: "arguments" }) ||
+        (t.isMetaProperty(node) && node.meta.name !== "import") ||
+        (refName && t.isIdentifier(node, { name: refName }))
+      ) {
+        // TODO: Add early return support to t.traverseFast
+        throw null;
+      }
+    });
+    return false;
+  } catch {
+    return true;
+  }
+}
+
 function checkPrivateMethodUpdateError(
   path: NodePath<t.Class>,
   decoratedPrivateMethods: Set<string>,
@@ -810,6 +836,8 @@ function transformClass(
 
   const classDecorators = path.node.decorators;
   let hasElementDecorators = false;
+  let hasComputedKeysSideEffects = false;
+  let elemDecsUseFnContext = false;
 
   const generateClassPrivateUid = createLazyPrivateUidGeneratorForClass(path);
 
@@ -868,6 +896,9 @@ function transformClass(
           break;
       }
       hasElementDecorators = true;
+      elemDecsUseFnContext ||= element.node.decorators.some(dec =>
+        usesFunctionContextOrRef(dec, path.node.id?.name),
+      );
     } else if (element.node.type === "ClassAccessorProperty") {
       // @ts-expect-error todo: propertyVisitor.ClassAccessorProperty should be callable. Improve typings.
       propertyVisitor.ClassAccessorProperty(
@@ -896,6 +927,10 @@ function transformClass(
         isStatic,
       );
     }
+
+    if ("computed" in element.node && element.node.computed) {
+      hasComputedKeysSideEffects ||= !scopeParent.isStatic(element.node.key);
+    }
   }
 
   if (!classDecorators && !hasElementDecorators) {
@@ -922,14 +957,16 @@ function transformClass(
   // Memoise the this value `a.b` of decorator member expressions `@a.b.dec`,
   type HandleDecoratorExpressionsResult = {
     // whether the whole decorator list requires memoisation
-    needMemoise: boolean;
+    hasSideEffects: boolean;
+    usesFnContext: boolean;
     // the this value of each decorator if applicable
     decoratorsThis: (t.Expression | undefined)[];
   };
   function handleDecoratorExpressions(
     expressions: t.Expression[],
   ): HandleDecoratorExpressionsResult {
-    let needMemoise = false;
+    let hasSideEffects = false;
+    let usesFnContext = false;
     const decoratorsThis: (t.Expression | null)[] = [];
     for (const expression of expressions) {
       let object;
@@ -954,11 +991,21 @@ function transformClass(
         }
       }
       decoratorsThis.push(object);
-      needMemoise ||= !scopeParent.isStatic(expression);
+      hasSideEffects ||= !scopeParent.isStatic(expression);
+      usesFnContext ||= usesFunctionContextOrRef(
+        expression,
+        path.node.id?.name,
+      );
     }
-    return { needMemoise, decoratorsThis };
+    return { hasSideEffects, usesFnContext, decoratorsThis };
   }
 
+  const willExtractSomeElemDecs =
+    hasComputedKeysSideEffects ||
+    (process.env.BABEL_8_BREAKING
+      ? elemDecsUseFnContext
+      : elemDecsUseFnContext || version !== "2023-11");
+
   let needsDeclaraionForClassBinding = false;
   let classDecorationsFlag = 0;
   let classDecorations: t.Expression[] = [];
@@ -971,7 +1018,7 @@ function transformClass(
     path.node.decorators = null;
 
     const decoratorExpressions = classDecorators.map(el => el.expression);
-    const { needMemoise, decoratorsThis } =
+    const { hasSideEffects, decoratorsThis } =
       handleDecoratorExpressions(decoratorExpressions);
 
     const { haveThis, decs } = generateDecorationList(
@@ -982,7 +1029,7 @@ function transformClass(
     classDecorationsFlag = haveThis ? 1 : 0;
     classDecorations = decs;
 
-    if (needMemoise) {
+    if (hasSideEffects && willExtractSomeElemDecs) {
       classDecorationsId = memoiseExpression(
         t.arrayExpression(classDecorations),
         "classDecs",
@@ -1042,16 +1089,22 @@ function transformClass(
 
       if (hasDecorators) {
         const decoratorExpressions = decorators.map(d => d.expression);
-        const { needMemoise, decoratorsThis } =
-          handleDecoratorExpressions(decoratorExpressions);
+        const {
+          hasSideEffects,
+          usesFnContext: usesFunctionContext,
+          decoratorsThis,
+        } = handleDecoratorExpressions(decoratorExpressions);
         const { decs, haveThis } = generateDecorationList(
           decoratorExpressions,
           decoratorsThis,
           version,
         );
         decoratorsHaveThis = haveThis;
         decoratorsArray = decs.length === 1 ? decs[0] : t.arrayExpression(decs);
-        if (needMemoise) {
+        if (
+          usesFunctionContext ||
+          (hasSideEffects && willExtractSomeElemDecs)
+        ) {
           decoratorsArray = memoiseExpression(decoratorsArray, name + "Decs");
         }
       }

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-classes--to-es2015/replacement-static-decorator-initializer-this/output.js

@@ -1,4 +1,4 @@
-var _initStatic, _initClass, _accessorDecs, _init_accessor, _init_extra_accessor, _getterDecs, _setterDecs, _methodDecs, _propertyDecs, _init_property, _init_extra_property, _A, _temp;
+var _initStatic, _initClass, _init_accessor, _init_extra_accessor, _init_property, _init_extra_property, _A, _temp;
 let original, replaced, accessorThis, getterThis, setterThis, methodThis, propertyThis, classThis;
 function dec(Klass, context) {
   original = Klass;
@@ -15,11 +15,6 @@ function captureInitializerThis(callback) {
     });
   };
 }
-_accessorDecs = captureInitializerThis(v => accessorThis = v);
-_getterDecs = captureInitializerThis(v => getterThis = v);
-_setterDecs = captureInitializerThis(v => setterThis = v);
-_methodDecs = captureInitializerThis(v => methodThis = v);
-_propertyDecs = captureInitializerThis(v => propertyThis = v);
 let _Foo;
 new (_A = /*#__PURE__*/new WeakMap(), (_temp = class extends babelHelpers.identity {
   constructor() {
@@ -44,7 +39,7 @@ new (_A = /*#__PURE__*/new WeakMap(), (_temp = class extends babelHelpers.identi
     ({
       e: [_init_accessor, _init_extra_accessor, _init_property, _init_extra_property, _initStatic],
       c: [_Foo, _initClass]
-    } = babelHelpers.applyDecs2311(_Foo2, [dec], [[_accessorDecs, 9, "accessor"], [_getterDecs, 11, "getter"], [_setterDecs, 12, "setter"], [_methodDecs, 10, "method"], [_propertyDecs, 8, "property"]]));
+    } = babelHelpers.applyDecs2311(_Foo2, [dec], [[captureInitializerThis(v => accessorThis = v), 9, "accessor"], [captureInitializerThis(v => getterThis = v), 11, "getter"], [captureInitializerThis(v => setterThis = v), 12, "setter"], [captureInitializerThis(v => methodThis = v), 10, "method"], [captureInitializerThis(v => propertyThis = v), 8, "property"]]));
     _initStatic(_Foo2);
   })();
 })(), _temp))();

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-classes/inheritance/output.js

@@ -1,20 +1,18 @@
-var _initClass, _classDecs, _initClass2, _classDecs2, _Bar2;
+var _initClass, _initClass2, _Bar2;
 const dec = () => {};
-_classDecs = [dec1];
 let _Bar;
 class Bar {
   static {
-    [_Bar, _initClass] = babelHelpers.applyDecs2311(this, _classDecs, []).c;
+    [_Bar, _initClass] = babelHelpers.applyDecs2311(this, [dec1], []).c;
   }
   static {
     _initClass();
   }
 }
-_classDecs2 = [dec2];
 let _Foo;
 class Foo extends (_Bar2 = _Bar) {
   static {
-    [_Foo, _initClass2] = babelHelpers.applyDecs2311(this, _classDecs2, [], 0, void 0, _Bar2).c;
+    [_Foo, _initClass2] = babelHelpers.applyDecs2311(this, [dec2], [], 0, void 0, _Bar2).c;
   }
   static {
     _initClass2();

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-classes/replacement-static-decorator-initializer-this/output.js

@@ -1,4 +1,4 @@
-var _initStatic, _initClass, _accessorDecs, _init_accessor, _init_extra_accessor, _getterDecs, _setterDecs, _methodDecs, _propertyDecs, _init_property, _init_extra_property;
+var _initStatic, _initClass, _init_accessor, _init_extra_accessor, _init_property, _init_extra_property;
 let original, replaced, accessorThis, getterThis, setterThis, methodThis, propertyThis, classThis;
 function dec(Klass, context) {
   original = Klass;
@@ -15,11 +15,6 @@ function captureInitializerThis(callback) {
     });
   };
 }
-_accessorDecs = captureInitializerThis(v => accessorThis = v);
-_getterDecs = captureInitializerThis(v => getterThis = v);
-_setterDecs = captureInitializerThis(v => setterThis = v);
-_methodDecs = captureInitializerThis(v => methodThis = v);
-_propertyDecs = captureInitializerThis(v => propertyThis = v);
 let _Foo;
 new class extends babelHelpers.identity {
   static {
@@ -28,7 +23,7 @@ new class extends babelHelpers.identity {
         ({
           e: [_init_accessor, _init_extra_accessor, _init_property, _init_extra_property, _initStatic],
           c: [_Foo, _initClass]
-        } = babelHelpers.applyDecs2311(this, [dec], [[_accessorDecs, 9, "accessor"], [_getterDecs, 11, "getter"], [_setterDecs, 12, "setter"], [_methodDecs, 10, "method"], [_propertyDecs, 8, "property"]]));
+        } = babelHelpers.applyDecs2311(this, [dec], [[captureInitializerThis(v => accessorThis = v), 9, "accessor"], [captureInitializerThis(v => getterThis = v), 11, "getter"], [captureInitializerThis(v => setterThis = v), 12, "setter"], [captureInitializerThis(v => methodThis = v), 10, "method"], [captureInitializerThis(v => propertyThis = v), 8, "property"]]));
         _initStatic(this);
       }
       static get accessor() {

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-exported/default-anonymous/output.mjs

@@ -1,9 +1,8 @@
-var _initClass, _classDecs;
-_classDecs = [dec];
+var _initClass;
 let _A;
 class A {
   static {
-    [_A, _initClass] = babelHelpers.applyDecs2311(this, _classDecs, []).c;
+    [_A, _initClass] = babelHelpers.applyDecs2311(this, [dec], []).c;
   }
   static {
     _initClass();

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-exported/default-named/output.mjs

@@ -1,9 +1,8 @@
-var _initClass, _classDecs;
-_classDecs = [dec];
+var _initClass;
 let _default2;
 class _default {
   static {
-    [_default2, _initClass] = babelHelpers.applyDecs2311(babelHelpers.setFunctionName(this, "default"), _classDecs, []).c;
+    [_default2, _initClass] = babelHelpers.applyDecs2311(babelHelpers.setFunctionName(this, "default"), [dec], []).c;
   }
   static {
     _initClass();

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-exported/member-decorator/output.mjs

@@ -1,8 +1,7 @@
-var _xDecs, _init_x, _init_extra_x;
-_xDecs = dec;
+var _init_x, _init_extra_x;
 export class A {
   static {
-    [_init_x, _init_extra_x] = babelHelpers.applyDecs2311(this, [], [[_xDecs, 0, "x"]]).e;
+    [_init_x, _init_extra_x] = babelHelpers.applyDecs2311(this, [], [[dec, 0, "x"]]).e;
   }
   constructor() {
     _init_extra_x(this);

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-exported/named/output.mjs

@@ -1,9 +1,8 @@
-var _initClass, _classDecs;
-_classDecs = [dec];
+var _initClass;
 let _A;
 class A {
   static {
-    [_A, _initClass] = babelHelpers.applyDecs2311(this, _classDecs, []).c;
+    [_A, _initClass] = babelHelpers.applyDecs2311(this, [dec], []).c;
   }
   static {
     _initClass();

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-methods--to-es2015/private-async-and-generator/output.js

@@ -1,7 +1,4 @@
-var _initProto, _aDecs, _call_a, _gDecs, _call_g, _agDecs, _call_ag, _Foo;
-_aDecs = dec;
-_gDecs = dec;
-_agDecs = dec;
+var _initProto, _call_a, _call_g, _call_ag, _Foo;
 var _ag = /*#__PURE__*/new WeakMap();
 var _g = /*#__PURE__*/new WeakMap();
 var _a = /*#__PURE__*/new WeakMap();
@@ -14,4 +11,4 @@ class Foo {
   }
 }
 _Foo = Foo;
-[_call_a, _call_g, _call_ag, _initProto] = babelHelpers.applyDecs2311(_Foo, [], [[_aDecs, 2, "a", async function () {}], [_gDecs, 2, "g", function* () {}], [_agDecs, 2, "ag", async function* () {}]], 0, _ => _a.has(babelHelpers.checkInRHS(_))).e;
+[_call_a, _call_g, _call_ag, _initProto] = babelHelpers.applyDecs2311(_Foo, [], [[dec, 2, "a", async function () {}], [dec, 2, "g", function* () {}], [dec, 2, "ag", async function* () {}]], 0, _ => _a.has(babelHelpers.checkInRHS(_))).e;

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-methods/private-async-and-generator/output.js

@@ -1,10 +1,7 @@
-var _initProto, _aDecs, _call_a, _gDecs, _call_g, _agDecs, _call_ag;
-_aDecs = dec;
-_gDecs = dec;
-_agDecs = dec;
+var _initProto, _call_a, _call_g, _call_ag;
 class Foo {
   static {
-    [_call_a, _call_g, _call_ag, _initProto] = babelHelpers.applyDecs2311(this, [], [[_aDecs, 2, "a", async function () {}], [_gDecs, 2, "g", function* () {}], [_agDecs, 2, "ag", async function* () {}]], 0, _ => #a in _).e;
+    [_call_a, _call_g, _call_ag, _initProto] = babelHelpers.applyDecs2311(this, [], [[dec, 2, "a", async function () {}], [dec, 2, "g", function* () {}], [dec, 2, "ag", async function* () {}]], 0, _ => #a in _).e;
   }
   constructor() {
     _initProto(this);

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-misc--to-es2015/this/output.js

@@ -1,7 +1,4 @@
-var _initClass, _obj, _classDecs, _xDecs, _init_x, _init_extra_x, _yDecs, _init_y, _init_extra_y, _A2;
-_classDecs = [_obj = o1, _obj.dec, void 0, dec, _obj = o2, _obj.dec];
-_xDecs = [_obj = o2, _obj.dec, _obj = o3.o, _obj.dec];
-_yDecs = [_obj = o2, _obj.dec, void 0, dec];
+var _initClass, _obj, _init_x, _init_extra_x, _init_y, _init_extra_y, _A2;
 let _A;
 class A {
   constructor() {
@@ -14,5 +11,5 @@ _A2 = A;
 ({
   e: [_init_x, _init_extra_x, _init_y, _init_extra_y],
   c: [_A, _initClass]
-} = babelHelpers.applyDecs2311(_A2, _classDecs, [[_xDecs, 16, "x"], [_yDecs, 16, "y"]], 1));
+} = babelHelpers.applyDecs2311(_A2, [_obj = o1, _obj.dec, void 0, dec, _obj = o2, _obj.dec], [[[_obj = o2, _obj.dec, _obj = o3.o, _obj.dec], 16, "x"], [[_obj = o2, _obj.dec, void 0, dec], 16, "y"]], 1));
 _initClass();

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-misc--to-es2015/valid-expression-formats/output.js

@@ -1,7 +1,5 @@
-var _initProto, _initClass, _obj, _classDecs, _methodDecs, _Foo2;
+var _initProto, _initClass, _obj, _Foo2;
 const dec = () => {};
-_classDecs = [void 0, dec, void 0, call(), void 0, chain.expr(), void 0, arbitrary + expr, _obj = array, _obj[expr]];
-_methodDecs = [void 0, dec, void 0, call(), void 0, chain.expr(), void 0, arbitrary + expr, _obj = array, _obj[expr]];
 let _Foo;
 var _a = /*#__PURE__*/new WeakMap();
 class Foo {
@@ -23,5 +21,5 @@ _Foo2 = Foo;
 ({
   e: [_initProto],
   c: [_Foo, _initClass]
-} = babelHelpers.applyDecs2311(_Foo2, _classDecs, [[_methodDecs, 18, "method"]], 1));
+} = babelHelpers.applyDecs2311(_Foo2, [void 0, dec, void 0, call(), void 0, chain.expr(), void 0, arbitrary + expr, _obj = array, _obj[expr]], [[[void 0, dec, void 0, call(), void 0, chain.expr(), void 0, arbitrary + expr, _obj = array, _obj[expr]], 18, "method"]], 1));
 _initClass();

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-misc/class-tdz-during-decorators/exec.js → packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-misc/class-not-available-during-decorators/exec.js

@@ -6,7 +6,7 @@ function dec(fn) {
 }
 
 @dec(() => {
-  expect(() => Foo).toThrow(ReferenceError);
+  expect(() => Foo.x).toThrow();
   didRun = true;
 }) class Foo {}
 

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-misc/initProto-existing-derived-constructor-multiple-super/output.js

@@ -1,9 +1,8 @@
-var _initProto, _methodDecs, _B, _initProto2, _methodDecs2, _B2;
+var _initProto, _B, _initProto2, _B2;
 const dec = () => {};
-_methodDecs = deco;
 class A extends (_B = B) {
   static {
-    [_initProto] = babelHelpers.applyDecs2311(this, [], [[_methodDecs, 2, "method"]], 0, void 0, _B).e;
+    [_initProto] = babelHelpers.applyDecs2311(this, [], [[deco, 2, "method"]], 0, void 0, _B).e;
   }
   constructor() {
     if (Math.random() > 0.5) {
@@ -14,10 +13,9 @@ class A extends (_B = B) {
   }
   method() {}
 }
-_methodDecs2 = deco;
 class C extends (_B2 = B) {
   static {
-    [_initProto2] = babelHelpers.applyDecs2311(this, [], [[_methodDecs2, 2, "method"]], 0, void 0, _B2).e;
+    [_initProto2] = babelHelpers.applyDecs2311(this, [], [[deco, 2, "method"]], 0, void 0, _B2).e;
   }
   constructor() {
     try {

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-misc/this/output.js

@@ -1,14 +1,11 @@
-var _initClass, _obj, _classDecs, _xDecs, _init_x, _init_extra_x, _yDecs, _init_y, _init_extra_y;
-_classDecs = [_obj = o1, _obj.dec, void 0, dec, _obj = o2, _obj.dec, _obj = o4.o(), _obj.dec];
-_xDecs = [_obj = o2, _obj.dec, _obj = o3.o, _obj.dec, _obj = o4.o(), _obj.dec];
-_yDecs = [_obj = o2, _obj.dec, void 0, dec];
+var _initClass, _obj, _init_x, _init_extra_x, _init_y, _init_extra_y;
 let _A;
 class A {
   static {
     ({
       e: [_init_x, _init_extra_x, _init_y, _init_extra_y],
       c: [_A, _initClass]
-    } = babelHelpers.applyDecs2311(this, _classDecs, [[_xDecs, 16, "x"], [_yDecs, 16, "y"]], 1));
+    } = babelHelpers.applyDecs2311(this, [_obj = o1, _obj.dec, void 0, dec, _obj = o2, _obj.dec, _obj = o4.o(), _obj.dec], [[[_obj = o2, _obj.dec, _obj = o3.o, _obj.dec, _obj = o4.o(), _obj.dec], 16, "x"], [[_obj = o2, _obj.dec, void 0, dec], 16, "y"]], 1));
   }
   constructor() {
     _init_extra_y(this);