Rework entity name decorator metadata fallback emit to not throw at runtime (#25421)

* Rework entity name decorator metadata fallback emit to not throw at runtime

* Remove trailing whitespace

src/compiler/transformers/ts.ts

@@ -1982,18 +1982,16 @@ namespace ts {
             const kind = resolver.getTypeReferenceSerializationKind(node.typeName, currentNameScope || currentLexicalScope);
             switch (kind) {
                 case TypeReferenceSerializationKind.Unknown:
-                    const serialized = serializeEntityNameAsExpression(node.typeName, /*useFallback*/ true);
+                    const serialized = serializeEntityNameAsExpressionFallback(node.typeName);
                     const temp = createTempVariable(hoistVariableDeclaration);
-                    return createLogicalOr(
-                        createLogicalAnd(
-                            createTypeCheck(createAssignment(temp, serialized), "function"),
-                            temp
-                        ),
+                    return createConditional(
+                        createTypeCheck(createAssignment(temp, serialized), "function"),
+                        temp,
                         createIdentifier("Object")
                     );
 
                 case TypeReferenceSerializationKind.TypeWithConstructSignatureAndValue:
-                    return serializeEntityNameAsExpression(node.typeName, /*useFallback*/ false);
+                    return serializeEntityNameAsExpression(node.typeName);
 
                 case TypeReferenceSerializationKind.VoidNullableOrNeverType:
                     return createVoidZero();
@@ -2028,14 +2026,46 @@ namespace ts {
             }
         }
 
+        function createCheckedValue(left: Expression, right: Expression) {
+            return createLogicalAnd(
+                createStrictInequality(createTypeOf(left), createLiteral("undefined")),
+                right
+            );
+        }
+
+        /**
+         * Serializes an entity name which may not exist at runtime, but whose access shouldn't throw
+         *
+         * @param node The entity name to serialize.
+         */
+        function serializeEntityNameAsExpressionFallback(node: EntityName): BinaryExpression {
+            if (node.kind === SyntaxKind.Identifier) {
+                // A -> typeof A !== undefined && A
+                const copied = serializeEntityNameAsExpression(node);
+                return createCheckedValue(copied, copied);
+            }
+            if (node.left.kind === SyntaxKind.Identifier) {
+                // A.B -> typeof A !== undefined && A.B
+                return createCheckedValue(serializeEntityNameAsExpression(node.left), serializeEntityNameAsExpression(node));
+            }
+            // A.B.C -> typeof A !== undefined && (_a = A.B) !== void 0 && _a.C
+            const left = serializeEntityNameAsExpressionFallback(node.left);
+            const temp = createTempVariable(hoistVariableDeclaration);
+            return createLogicalAnd(
+                    createLogicalAnd(
+                    left.left,
+                    createStrictInequality(createAssignment(temp, left.right), createVoidZero())
+                ),
+                createPropertyAccess(temp, node.right)
+            );
+        }
+
         /**
          * Serializes an entity name as an expression for decorator type metadata.
          *
          * @param node The entity name to serialize.
-         * @param useFallback A value indicating whether to use logical operators to test for the
-         *                    entity name at runtime.
          */
-        function serializeEntityNameAsExpression(node: EntityName, useFallback: boolean): SerializedEntityNameAsExpression {
+        function serializeEntityNameAsExpression(node: EntityName): SerializedEntityNameAsExpression {
             switch (node.kind) {
                 case SyntaxKind.Identifier:
                     // Create a clone of the name with a new parent, and treat it as if it were
@@ -2044,20 +2074,11 @@ namespace ts {
                     name.flags &= ~NodeFlags.Synthesized;
                     name.original = undefined;
                     name.parent = getParseTreeNode(currentLexicalScope); // ensure the parent is set to a parse tree node.
-                    if (useFallback) {
-                        return createLogicalAnd(
-                            createStrictInequality(
-                                createTypeOf(name),
-                                createLiteral("undefined")
-                            ),
-                            name
-                        );
-                    }
 
                     return name;
 
                 case SyntaxKind.QualifiedName:
-                    return serializeQualifiedNameAsExpression(node, useFallback);
+                    return serializeQualifiedNameAsExpression(node);
             }
         }
 
@@ -2068,26 +2089,8 @@ namespace ts {
          * @param useFallback A value indicating whether to use logical operators to test for the
          *                    qualified name at runtime.
          */
-        function serializeQualifiedNameAsExpression(node: QualifiedName, useFallback: boolean): PropertyAccessExpression {
-            let left: SerializedEntityNameAsExpression;
-            if (node.left.kind === SyntaxKind.Identifier) {
-                left = serializeEntityNameAsExpression(node.left, useFallback);
-            }
-            else if (useFallback) {
-                const temp = createTempVariable(hoistVariableDeclaration);
-                left = createLogicalAnd(
-                    createAssignment(
-                        temp,
-                        serializeEntityNameAsExpression(node.left, /*useFallback*/ true)
-                    ),
-                    temp
-                );
-            }
-            else {
-                left = serializeEntityNameAsExpression(node.left, /*useFallback*/ false);
-            }
-
-            return createPropertyAccess(left, node.right);
+        function serializeQualifiedNameAsExpression(node: QualifiedName): SerializedEntityNameAsExpression {
+            return createPropertyAccess(serializeEntityNameAsExpression(node.left), node.right);
         }
 
         /**

tests/baselines/reference/decoratorMetadataNoLibIsolatedModulesTypes.js

@@ -23,7 +23,7 @@ var B = /** @class */ (function () {
     var _a;
     __decorate([
         Decorate,
-        __metadata("design:type", typeof (_a = typeof Map !== "undefined" && Map) === "function" && _a || Object)
+        __metadata("design:type", typeof (_a = typeof Map !== "undefined" && Map) === "function" ? _a : Object)
     ], B.prototype, "member");
     return B;
 }());

tests/baselines/reference/decoratorMetadataWithImportDeclarationNameCollision4.js

@@ -49,7 +49,7 @@ var MyClass = /** @class */ (function () {
     var _a;
     MyClass = __decorate([
         someDecorator,
-        __metadata("design:paramtypes", [typeof (_a = (typeof db_1.default !== "undefined" && db_1.default).db) === "function" && _a || Object])
+        __metadata("design:paramtypes", [typeof (_a = typeof db_1.default !== "undefined" && db_1.default.db) === "function" ? _a : Object])
     ], MyClass);
     return MyClass;
 }());

tests/baselines/reference/decoratorMetadataWithImportDeclarationNameCollision7.js

@@ -49,7 +49,7 @@ var MyClass = /** @class */ (function () {
     var _a;
     MyClass = __decorate([
         someDecorator,
-        __metadata("design:paramtypes", [typeof (_a = (typeof db_1.default !== "undefined" && db_1.default).db) === "function" && _a || Object])
+        __metadata("design:paramtypes", [typeof (_a = typeof db_1.default !== "undefined" && db_1.default.db) === "function" ? _a : Object])
     ], MyClass);
     return MyClass;
 }());

tests/baselines/reference/experimentalDecoratorMetadataUnresolvedTypeObjectInEmit.errors.txt

@@ -0,0 +1,22 @@
+tests/cases/compiler/usage.ts(2,8): error TS2304: Cannot find name 'decorate'.
+tests/cases/compiler/usage.ts(2,31): error TS2694: Namespace 'A.B.C.D' has no exported member 'E'.
+
+
+==== tests/cases/compiler/types.d.ts (0 errors) ====
+    declare namespace A {
+        export namespace B {
+            export namespace C {
+                export namespace D {
+                }
+            }
+        }
+    }
+==== tests/cases/compiler/usage.ts (2 errors) ====
+    class Foo {
+        f(@decorate user: A.B.C.D.E): void {}
+           ~~~~~~~~
+!!! error TS2304: Cannot find name 'decorate'.
+                                  ~
+!!! error TS2694: Namespace 'A.B.C.D' has no exported member 'E'.
+    }
+    

tests/baselines/reference/experimentalDecoratorMetadataUnresolvedTypeObjectInEmit.js

@@ -0,0 +1,43 @@
+//// [tests/cases/compiler/experimentalDecoratorMetadataUnresolvedTypeObjectInEmit.ts] ////
+
+//// [types.d.ts]
+declare namespace A {
+    export namespace B {
+        export namespace C {
+            export namespace D {
+            }
+        }
+    }
+}
+//// [usage.ts]
+class Foo {
+    f(@decorate user: A.B.C.D.E): void {}
+}
+
+
+//// [usage.js]
+var __decorate = (this && this.__decorate) || function (decorators, target, key, desc) {
+    var c = arguments.length, r = c < 3 ? target : desc === null ? desc = Object.getOwnPropertyDescriptor(target, key) : desc, d;
+    if (typeof Reflect === "object" && typeof Reflect.decorate === "function") r = Reflect.decorate(decorators, target, key, desc);
+    else for (var i = decorators.length - 1; i >= 0; i--) if (d = decorators[i]) r = (c < 3 ? d(r) : c > 3 ? d(target, key, r) : d(target, key)) || r;
+    return c > 3 && r && Object.defineProperty(target, key, r), r;
+};
+var __metadata = (this && this.__metadata) || function (k, v) {
+    if (typeof Reflect === "object" && typeof Reflect.metadata === "function") return Reflect.metadata(k, v);
+};
+var __param = (this && this.__param) || function (paramIndex, decorator) {
+    return function (target, key) { decorator(target, key, paramIndex); }
+};
+var Foo = /** @class */ (function () {
+    function Foo() {
+    }
+    Foo.prototype.f = function (user) { };
+    var _a, _b, _c, _d;
+    __decorate([
+        __param(0, decorate),
+        __metadata("design:type", Function),
+        __metadata("design:paramtypes", [typeof (_d = typeof A !== "undefined" && (_a = A.B) !== void 0 && (_b = _a.C) !== void 0 && (_c = _b.D) !== void 0 && _c.E) === "function" ? _d : Object]),
+        __metadata("design:returntype", void 0)
+    ], Foo.prototype, "f");
+    return Foo;
+}());

tests/baselines/reference/experimentalDecoratorMetadataUnresolvedTypeObjectInEmit.symbols

@@ -0,0 +1,29 @@
+=== tests/cases/compiler/types.d.ts ===
+declare namespace A {
+>A : Symbol(A, Decl(types.d.ts, 0, 0))
+
+    export namespace B {
+>B : Symbol(B, Decl(types.d.ts, 0, 21))
+
+        export namespace C {
+>C : Symbol(C, Decl(types.d.ts, 1, 24))
+
+            export namespace D {
+>D : Symbol(D, Decl(types.d.ts, 2, 28))
+            }
+        }
+    }
+}
+=== tests/cases/compiler/usage.ts ===
+class Foo {
+>Foo : Symbol(Foo, Decl(usage.ts, 0, 0))
+
+    f(@decorate user: A.B.C.D.E): void {}
+>f : Symbol(Foo.f, Decl(usage.ts, 0, 11))
+>user : Symbol(user, Decl(usage.ts, 1, 6))
+>A : Symbol(A, Decl(types.d.ts, 0, 0))
+>B : Symbol(A.B, Decl(types.d.ts, 0, 21))
+>C : Symbol(A.B.C, Decl(types.d.ts, 1, 24))
+>D : Symbol(A.B.C.D, Decl(types.d.ts, 2, 28))
+}
+

tests/baselines/reference/experimentalDecoratorMetadataUnresolvedTypeObjectInEmit.types

@@ -0,0 +1,31 @@
+=== tests/cases/compiler/types.d.ts ===
+declare namespace A {
+>A : any
+
+    export namespace B {
+>B : any
+
+        export namespace C {
+>C : any
+
+            export namespace D {
+>D : any
+            }
+        }
+    }
+}
+=== tests/cases/compiler/usage.ts ===
+class Foo {
+>Foo : Foo
+
+    f(@decorate user: A.B.C.D.E): void {}
+>f : (user: any) => void
+>decorate : any
+>user : any
+>A : any
+>B : any
+>C : any
+>D : any
+>E : No type information available!
+}
+

tests/baselines/reference/project/emitDecoratorMetadataCommonJSISolatedModules/amd/main.js

@@ -17,7 +17,7 @@ define(["require", "exports", "angular2/core"], function (require, exports, ng)
         var _a;
         MyClass1 = __decorate([
             foo,
-            __metadata("design:paramtypes", [typeof (_a = (typeof ng !== "undefined" && ng).ElementRef) === "function" && _a || Object])
+            __metadata("design:paramtypes", [typeof (_a = typeof ng !== "undefined" && ng.ElementRef) === "function" ? _a : Object])
         ], MyClass1);
         return MyClass1;
     }());

tests/baselines/reference/project/emitDecoratorMetadataCommonJSISolatedModules/node/main.js

@@ -17,7 +17,7 @@ var MyClass1 = /** @class */ (function () {
     var _a;
     MyClass1 = __decorate([
         foo,
-        __metadata("design:paramtypes", [typeof (_a = (typeof ng !== "undefined" && ng).ElementRef) === "function" && _a || Object])
+        __metadata("design:paramtypes", [typeof (_a = typeof ng !== "undefined" && ng.ElementRef) === "function" ? _a : Object])
     ], MyClass1);
     return MyClass1;
 }());

tests/baselines/reference/project/emitDecoratorMetadataCommonJSISolatedModulesNoResolve/amd/main.js

@@ -17,7 +17,7 @@ define(["require", "exports", "angular2/core"], function (require, exports, ng)
         var _a;
         MyClass1 = __decorate([
             foo,
-            __metadata("design:paramtypes", [typeof (_a = (typeof ng !== "undefined" && ng).ElementRef) === "function" && _a || Object])
+            __metadata("design:paramtypes", [typeof (_a = typeof ng !== "undefined" && ng.ElementRef) === "function" ? _a : Object])
         ], MyClass1);
         return MyClass1;
     }());

tests/baselines/reference/project/emitDecoratorMetadataCommonJSISolatedModulesNoResolve/node/main.js

@@ -17,7 +17,7 @@ var MyClass1 = /** @class */ (function () {
     var _a;
     MyClass1 = __decorate([
         foo,
-        __metadata("design:paramtypes", [typeof (_a = (typeof ng !== "undefined" && ng).ElementRef) === "function" && _a || Object])
+        __metadata("design:paramtypes", [typeof (_a = typeof ng !== "undefined" && ng.ElementRef) === "function" ? _a : Object])
     ], MyClass1);
     return MyClass1;
 }());

tests/baselines/reference/project/emitDecoratorMetadataSystemJS/amd/main.js

@@ -17,7 +17,7 @@ define(["require", "exports", "angular2/core"], function (require, exports, ng)
         var _a;
         MyClass1 = __decorate([
             foo,
-            __metadata("design:paramtypes", [typeof (_a = (typeof ng !== "undefined" && ng).ElementRef) === "function" && _a || Object])
+            __metadata("design:paramtypes", [typeof (_a = typeof ng !== "undefined" && ng.ElementRef) === "function" ? _a : Object])
         ], MyClass1);
         return MyClass1;
     }());

tests/baselines/reference/project/emitDecoratorMetadataSystemJS/node/main.js

@@ -17,7 +17,7 @@ var MyClass1 = /** @class */ (function () {
     var _a;
     MyClass1 = __decorate([
         foo,
-        __metadata("design:paramtypes", [typeof (_a = (typeof ng !== "undefined" && ng).ElementRef) === "function" && _a || Object])
+        __metadata("design:paramtypes", [typeof (_a = typeof ng !== "undefined" && ng.ElementRef) === "function" ? _a : Object])
     ], MyClass1);
     return MyClass1;
 }());

tests/baselines/reference/project/emitDecoratorMetadataSystemJSISolatedModules/amd/main.js

@@ -17,7 +17,7 @@ define(["require", "exports", "angular2/core"], function (require, exports, ng)
         var _a;
         MyClass1 = __decorate([
             foo,
-            __metadata("design:paramtypes", [typeof (_a = (typeof ng !== "undefined" && ng).ElementRef) === "function" && _a || Object])
+            __metadata("design:paramtypes", [typeof (_a = typeof ng !== "undefined" && ng.ElementRef) === "function" ? _a : Object])
         ], MyClass1);
         return MyClass1;
     }());

tests/baselines/reference/project/emitDecoratorMetadataSystemJSISolatedModules/node/main.js

@@ -17,7 +17,7 @@ var MyClass1 = /** @class */ (function () {
     var _a;
     MyClass1 = __decorate([
         foo,
-        __metadata("design:paramtypes", [typeof (_a = (typeof ng !== "undefined" && ng).ElementRef) === "function" && _a || Object])
+        __metadata("design:paramtypes", [typeof (_a = typeof ng !== "undefined" && ng.ElementRef) === "function" ? _a : Object])
     ], MyClass1);
     return MyClass1;
 }());

tests/baselines/reference/project/emitDecoratorMetadataSystemJSISolatedModulesNoResolve/amd/main.js

@@ -17,7 +17,7 @@ define(["require", "exports", "angular2/core"], function (require, exports, ng)
         var _a;
         MyClass1 = __decorate([
             foo,
-            __metadata("design:paramtypes", [typeof (_a = (typeof ng !== "undefined" && ng).ElementRef) === "function" && _a || Object])
+            __metadata("design:paramtypes", [typeof (_a = typeof ng !== "undefined" && ng.ElementRef) === "function" ? _a : Object])
         ], MyClass1);
         return MyClass1;
     }());

tests/baselines/reference/project/emitDecoratorMetadataSystemJSISolatedModulesNoResolve/node/main.js

@@ -17,7 +17,7 @@ var MyClass1 = /** @class */ (function () {
     var _a;
     MyClass1 = __decorate([
         foo,
-        __metadata("design:paramtypes", [typeof (_a = (typeof ng !== "undefined" && ng).ElementRef) === "function" && _a || Object])
+        __metadata("design:paramtypes", [typeof (_a = typeof ng !== "undefined" && ng.ElementRef) === "function" ? _a : Object])
     ], MyClass1);
     return MyClass1;
 }());

tests/baselines/reference/transpile/Correctly serialize metadata when transpile with CommonJS option.js

@@ -17,7 +17,7 @@ var MyClass1 = /** @class */ (function () {
     var _a;
     MyClass1 = __decorate([
         fooexport,
-        __metadata("design:paramtypes", [typeof (_a = (typeof ng !== "undefined" && ng).ElementRef) === "function" && _a || Object])
+        __metadata("design:paramtypes", [typeof (_a = typeof ng !== "undefined" && ng.ElementRef) === "function" ? _a : Object])
     ], MyClass1);
     return MyClass1;
 }());

tests/baselines/reference/transpile/Correctly serialize metadata when transpile with CommonJS option.oldTranspile.js

@@ -17,7 +17,7 @@ var MyClass1 = /** @class */ (function () {
     var _a;
     MyClass1 = __decorate([
         fooexport,
-        __metadata("design:paramtypes", [typeof (_a = (typeof ng !== "undefined" && ng).ElementRef) === "function" && _a || Object])
+        __metadata("design:paramtypes", [typeof (_a = typeof ng !== "undefined" && ng.ElementRef) === "function" ? _a : Object])
     ], MyClass1);
     return MyClass1;
 }());

tests/baselines/reference/transpile/Correctly serialize metadata when transpile with System option.js

@@ -25,7 +25,7 @@ System.register(["angular2/core"], function (exports_1, context_1) {
                 var _a;
                 MyClass1 = __decorate([
                     fooexport,
-                    __metadata("design:paramtypes", [typeof (_a = (typeof ng !== "undefined" && ng).ElementRef) === "function" && _a || Object])
+                    __metadata("design:paramtypes", [typeof (_a = typeof ng !== "undefined" && ng.ElementRef) === "function" ? _a : Object])
                 ], MyClass1);
                 return MyClass1;
             }());

tests/baselines/reference/transpile/Correctly serialize metadata when transpile with System option.oldTranspile.js

@@ -25,7 +25,7 @@ System.register(["angular2/core"], function (exports_1, context_1) {
                 var _a;
                 MyClass1 = __decorate([
                     fooexport,
-                    __metadata("design:paramtypes", [typeof (_a = (typeof ng !== "undefined" && ng).ElementRef) === "function" && _a || Object])
+                    __metadata("design:paramtypes", [typeof (_a = typeof ng !== "undefined" && ng.ElementRef) === "function" ? _a : Object])
                 ], MyClass1);
                 return MyClass1;
             }());

tests/baselines/reference/transpile/Transpile with emit decorators and emit metadata.js

@@ -12,7 +12,7 @@ var MyClass = /** @class */ (function () {
     var _a;
     MyClass = __decorate([
         someDecorator,
-        __metadata("design:paramtypes", [typeof (_a = typeof db_1.db !== "undefined" && db_1.db) === "function" && _a || Object])
+        __metadata("design:paramtypes", [typeof (_a = typeof db_1.db !== "undefined" && db_1.db) === "function" ? _a : Object])
     ], MyClass);
     return MyClass;
 }());

tests/baselines/reference/transpile/Transpile with emit decorators and emit metadata.oldTranspile.js

@@ -12,7 +12,7 @@ var MyClass = /** @class */ (function () {
     var _a;
     MyClass = __decorate([
         someDecorator,
-        __metadata("design:paramtypes", [typeof (_a = typeof db_1.db !== "undefined" && db_1.db) === "function" && _a || Object])
+        __metadata("design:paramtypes", [typeof (_a = typeof db_1.db !== "undefined" && db_1.db) === "function" ? _a : Object])
     ], MyClass);
     return MyClass;
 }());

tests/cases/compiler/experimentalDecoratorMetadataUnresolvedTypeObjectInEmit.ts

@@ -0,0 +1,15 @@
+// @experimentalDecorators: true
+// @emitDecoratorMetadata: true
+// @filename: types.d.ts
+declare namespace A {
+    export namespace B {
+        export namespace C {
+            export namespace D {
+            }
+        }
+    }
+}
+// @filename: usage.ts
+class Foo {
+    f(@decorate user: A.B.C.D.E): void {}
+}