Merge pull request #13604 from Microsoft/intersectionBaseTypes

Allow deriving from object and intersection types

tests/cases/conformance/interfaces/interfaceDeclarations/interfaceExtendsObjectIntersection.ts

@@ -0,0 +1,55 @@
+// @strictNullChecks: true
+
+type T1 = { a: number };
+type T2 = T1 & { b: number };
+type T3 = () => void;
+type T4 = new () => { a: number };
+type T5 = number[];
+type T6 = [string, number];
+type T7 = { [P in 'a' | 'b' | 'c']: string };
+
+interface I1 extends T1 { x: string }
+interface I2 extends T2 { x: string }
+interface I3 extends T3 { x: string }
+interface I4 extends T4 { x: string }
+interface I5 extends T5 { x: string }
+interface I6 extends T6 { x: string }
+interface I7 extends T7 { x: string }
+
+type Constructor<T> = new () => T;
+declare function Constructor<T>(): Constructor<T>;
+
+class C1 extends Constructor<I1>() { x: string }
+class C2 extends Constructor<I2>() { x: string }
+class C3 extends Constructor<I3>() { x: string }
+class C4 extends Constructor<I4>() { x: string }
+class C5 extends Constructor<I5>() { x: string }
+class C6 extends Constructor<I6>() { x: string }
+class C7 extends Constructor<I7>() { x: string }
+
+declare function fx(x: string): string;
+declare class CX { a: number }
+declare enum EX { A, B, C }
+declare namespace NX { export const a = 1 }
+
+type T10 = typeof fx;
+type T11 = typeof CX;
+type T12 = typeof EX;
+type T13 = typeof NX;
+
+interface I10 extends T10 { x: string }
+interface I11 extends T11 { x: string }
+interface I12 extends T12 { x: string }
+interface I13 extends T13 { x: string }
+
+type Identifiable<T> = { _id: string } & T;
+
+interface I20 extends Partial<T1> { x: string }
+interface I21 extends Readonly<T1> { x: string }
+interface I22 extends Identifiable<T1> { x: string }
+interface I23 extends Identifiable<T1 & { b: number}> { x: string }
+
+class C20 extends Constructor<Partial<T1>>() { x: string }
+class C21 extends Constructor<Readonly<T1>>() { x: string }
+class C22 extends Constructor<Identifiable<T1>>() { x: string }
+class C23 extends Constructor<Identifiable<T1 & { b: number}>>() { x: string }

tests/cases/conformance/interfaces/interfaceDeclarations/interfaceExtendsObjectIntersectionErrors.ts

@@ -0,0 +1,49 @@
+// @strictNullChecks: true
+
+type T1 = { a: number };
+type T2 = T1 & { b: number };
+type T3 = number[];
+type T4 = [string, number];
+type T5 = { [P in 'a' | 'b' | 'c']: string };
+
+interface I1 extends T1 { a: string }
+interface I2 extends T2 { b: string }
+interface I3 extends T3 { length: string }
+interface I4 extends T4 { 0: number }
+interface I5 extends T5 { c: number }
+
+type Constructor<T> = new () => T;
+declare function Constructor<T>(): Constructor<T>;
+
+class C1 extends Constructor<T1>() { a: string }
+class C2 extends Constructor<T2>() { b: string }
+class C3 extends Constructor<T3>() { length: string }
+class C4 extends Constructor<T4>() { 0: number }
+class C5 extends Constructor<T5>() { c: number }
+
+declare class CX { static a: string }
+declare enum EX { A, B, C }
+declare namespace NX { export const a = "hello" }
+
+type TCX = typeof CX;
+type TEX = typeof EX;
+type TNX = typeof NX;
+
+interface I10 extends TCX { a: number }
+interface I11 extends TEX { C: string }
+interface I12 extends TNX { a: number }
+interface I14 extends TCX { [x: string]: number }
+interface I15 extends TEX { [x: string]: number }
+interface I16 extends TNX { [x: string]: number }
+
+type Identifiable<T> = { _id: string } & T;
+
+interface I20 extends Partial<T1> { a: string }
+interface I21 extends Readonly<T1> { a: string }
+interface I22 extends Identifiable<T1> { a: string }
+interface I23 extends Identifiable<T1 & { b: number}> { a: string }
+
+type U = { a: number } | { b: string };
+
+interface I30 extends U { x: string }
+interface I31<T> extends T { x: string }

tests/cases/conformance/types/intersection/intersectionThisTypes.ts

@@ -0,0 +1,40 @@
+interface Thing1 {
+    a: number;
+    self(): this;
+}
+
+interface Thing2 {
+    b: number;
+    me(): this;
+}
+
+type Thing3 = Thing1 & Thing2;
+type Thing4 = Thing3 & string[];
+
+function f1(t: Thing3) {
+    t = t.self();
+    t = t.me().self().me();
+}
+
+interface Thing5 extends Thing4 {
+    c: string;
+}
+
+function f2(t: Thing5) {
+    t = t.self();
+    t = t.me().self().me();
+}
+
+interface Component {
+    extend<T>(props: T): this & T;
+}
+
+interface Label extends Component {
+    title: string;
+}
+
+function test(label: Label) {
+    const extended = label.extend({ id: 67 }).extend({ tag: "hello" });
+    extended.id;  // Ok
+    extended.tag;  // Ok
+}