Report error when referencing class name from decorator (#57666)

src/compiler/checker.ts

@@ -2834,7 +2834,23 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             }
             else if (isClassLike(declaration)) {
                 // still might be illegal if the usage is within a computed property name in the class (eg class A { static p = "a"; [A.p]() {} })
-                return !findAncestor(usage, n => isComputedPropertyName(n) && n.parent.parent === declaration);
+                // or when used within a decorator in the class (e.g. `@dec(A.x) class A { static x = "x" }`),
+                // except when used in a function that is not an IIFE (e.g., `@dec(() => A.x) class A { ... }`)
+                const container = findAncestor(usage, n =>
+                    n === declaration ? "quit" :
+                        isComputedPropertyName(n) ? n.parent.parent === declaration :
+                        isDecorator(n) && (n.parent === declaration ||
+                            isMethodDeclaration(n.parent) && n.parent.parent === declaration ||
+                            isGetOrSetAccessorDeclaration(n.parent) && n.parent.parent === declaration ||
+                            isPropertyDeclaration(n.parent) && n.parent.parent === declaration ||
+                            isParameter(n.parent) && n.parent.parent.parent === declaration));
+                if (!container) {
+                    return true;
+                }
+                if (isDecorator(container)) {
+                    return !!findAncestor(usage, n => n === container ? "quit" : isFunctionLike(n) && !getImmediatelyInvokedFunctionExpression(n));
+                }
+                return false;
             }
             else if (isPropertyDeclaration(declaration)) {
                 // still might be illegal if a self-referencing property initializer (eg private x = this.x)

tests/baselines/reference/decoratorReferences.js

@@ -3,7 +3,7 @@
 //// [decoratorReferences.ts]
 declare function y(...args: any[]): any;
 type T = number;
-@y(1 as T, C) // <-- T should be resolved to the type alias, not the type parameter of the class; C should resolve to the class
+@y(1 as T, () => C) // <-- T should be resolved to the type alias, not the type parameter of the class; C should resolve to the class
 class C<T> {
     @y(null as T) // <-- y should resolve to the function declaration, not the parameter; T should resolve to the type parameter of the class
     method(@y x, y) {} // <-- decorator y should be resolved at the class declaration, not the parameter.
@@ -29,7 +29,7 @@ var C = /** @class */ (function () {
         __param(0, y)
     ], C.prototype, "method", null);
     C = __decorate([
-        y(1, C) // <-- T should be resolved to the type alias, not the type parameter of the class; C should resolve to the class
+        y(1, function () { return C; }) // <-- T should be resolved to the type alias, not the type parameter of the class; C should resolve to the class
     ], C);
     return C;
 }());

tests/baselines/reference/decoratorReferences.symbols

@@ -8,7 +8,7 @@ declare function y(...args: any[]): any;
 type T = number;
 >T : Symbol(T, Decl(decoratorReferences.ts, 0, 40))
 
-@y(1 as T, C) // <-- T should be resolved to the type alias, not the type parameter of the class; C should resolve to the class
+@y(1 as T, () => C) // <-- T should be resolved to the type alias, not the type parameter of the class; C should resolve to the class
 >y : Symbol(y, Decl(decoratorReferences.ts, 0, 0))
 >T : Symbol(T, Decl(decoratorReferences.ts, 0, 40))
 >C : Symbol(C, Decl(decoratorReferences.ts, 1, 16))

tests/baselines/reference/decoratorReferences.types

@@ -8,11 +8,12 @@ declare function y(...args: any[]): any;
 type T = number;
 >T : number
 
-@y(1 as T, C) // <-- T should be resolved to the type alias, not the type parameter of the class; C should resolve to the class
->y(1 as T, C) : any
+@y(1 as T, () => C) // <-- T should be resolved to the type alias, not the type parameter of the class; C should resolve to the class
+>y(1 as T, () => C) : any
 >y : (...args: any[]) => any
 >1 as T : number
 >1 : 1
+>() => C : () => typeof C
 >C : typeof C
 
 class C<T> {

tests/baselines/reference/useBeforeDeclaration_classDecorators.1.errors.txt

@@ -0,0 +1,147 @@
+useBeforeDeclaration_classDecorators.1.ts(7,6): error TS2449: Class 'C2' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(10,13): error TS2449: Class 'C3' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(29,10): error TS2449: Class 'C5' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(30,10): error TS2449: Class 'C5' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(31,10): error TS2449: Class 'C5' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(32,10): error TS2449: Class 'C5' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(33,10): error TS2449: Class 'C5' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(35,10): error TS2449: Class 'C5' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(36,10): error TS2449: Class 'C5' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(37,10): error TS2449: Class 'C5' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(38,10): error TS2449: Class 'C5' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(39,10): error TS2449: Class 'C5' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(44,17): error TS2449: Class 'C6' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(45,17): error TS2449: Class 'C6' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(46,17): error TS2449: Class 'C6' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(47,17): error TS2449: Class 'C6' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(48,17): error TS2449: Class 'C6' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(50,17): error TS2449: Class 'C6' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(51,17): error TS2449: Class 'C6' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(52,17): error TS2449: Class 'C6' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(53,17): error TS2449: Class 'C6' used before its declaration.
+useBeforeDeclaration_classDecorators.1.ts(54,17): error TS2449: Class 'C6' used before its declaration.
+
+
+==== useBeforeDeclaration_classDecorators.1.ts (22 errors) ====
+    declare const dec: any;
+
+    // ok
+    @dec(() => C1) class C1 { }
+
+    // error
+    @dec(C2) class C2 { }
+         ~~
+!!! error TS2449: Class 'C2' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:7:16: 'C2' is declared here.
+
+    // error
+    @dec((() => C3)()) class C3 { }
+                ~~
+!!! error TS2449: Class 'C3' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:10:26: 'C3' is declared here.
+
+    // ok
+    class C4 {
+        @dec(() => C4) static method() {}
+        @dec(() => C4) static get x() { return this.y; }
+        @dec(() => C4) static set x(v) {}
+        @dec(() => C4) static y: any;
+        @dec(() => C4) static accessor z: any;
+
+        @dec(() => C4) method() {}
+        @dec(() => C4) get x() { return this.y; }
+        @dec(() => C4) set x(v) {}
+        @dec(() => C4) y: any;
+        @dec(() => C4) accessor z: any;
+    }
+
+    // error
+    class C5 {
+        @dec(C5) static method() {}
+             ~~
+!!! error TS2449: Class 'C5' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:28:7: 'C5' is declared here.
+        @dec(C5) static get x() { return this.y; }
+             ~~
+!!! error TS2449: Class 'C5' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:28:7: 'C5' is declared here.
+        @dec(C5) static set x(v) {}
+             ~~
+!!! error TS2449: Class 'C5' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:28:7: 'C5' is declared here.
+        @dec(C5) static y: any;
+             ~~
+!!! error TS2449: Class 'C5' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:28:7: 'C5' is declared here.
+        @dec(C5) static accessor z: any;
+             ~~
+!!! error TS2449: Class 'C5' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:28:7: 'C5' is declared here.
+
+        @dec(C5) method() {}
+             ~~
+!!! error TS2449: Class 'C5' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:28:7: 'C5' is declared here.
+        @dec(C5) get x() { return this.y; }
+             ~~
+!!! error TS2449: Class 'C5' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:28:7: 'C5' is declared here.
+        @dec(C5) set x(v) {}
+             ~~
+!!! error TS2449: Class 'C5' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:28:7: 'C5' is declared here.
+        @dec(C5) y: any;
+             ~~
+!!! error TS2449: Class 'C5' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:28:7: 'C5' is declared here.
+        @dec(C5) accessor z: any;
+             ~~
+!!! error TS2449: Class 'C5' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:28:7: 'C5' is declared here.
+    }
+
+    // error
+    class C6 {
+        @dec((() => C6)()) static method() {}
+                    ~~
+!!! error TS2449: Class 'C6' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:43:7: 'C6' is declared here.
+        @dec((() => C6)()) static get x() { return this.y; }
+                    ~~
+!!! error TS2449: Class 'C6' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:43:7: 'C6' is declared here.
+        @dec((() => C6)()) static set x(v) {}
+                    ~~
+!!! error TS2449: Class 'C6' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:43:7: 'C6' is declared here.
+        @dec((() => C6)()) static y: any;
+                    ~~
+!!! error TS2449: Class 'C6' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:43:7: 'C6' is declared here.
+        @dec((() => C6)()) static accessor z: any;
+                    ~~
+!!! error TS2449: Class 'C6' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:43:7: 'C6' is declared here.
+
+        @dec((() => C6)()) method() {}
+                    ~~
+!!! error TS2449: Class 'C6' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:43:7: 'C6' is declared here.
+        @dec((() => C6)()) get x() { return this.y; }
+                    ~~
+!!! error TS2449: Class 'C6' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:43:7: 'C6' is declared here.
+        @dec((() => C6)()) set x(v) {}
+                    ~~
+!!! error TS2449: Class 'C6' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:43:7: 'C6' is declared here.
+        @dec((() => C6)()) y: any;
+                    ~~
+!!! error TS2449: Class 'C6' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:43:7: 'C6' is declared here.
+        @dec((() => C6)()) accessor z: any;
+                    ~~
+!!! error TS2449: Class 'C6' used before its declaration.
+!!! related TS2728 useBeforeDeclaration_classDecorators.1.ts:43:7: 'C6' is declared here.
+    }
+