Cherry-pick PR #44290 into release-4.3 (#44425)

Component commits:
f3bf29a fix(44273): preserves 'override' modifier in JavaScript output

Co-authored-by: Oleksandr T <oleksandr.tarasiuk@outlook.com>

Author: TypeScript Bot

src/compiler/transformers/ts.ts

@@ -368,6 +368,7 @@ namespace ts {
                 case SyntaxKind.PrivateKeyword:
                 case SyntaxKind.ProtectedKeyword:
                 case SyntaxKind.AbstractKeyword:
+                case SyntaxKind.OverrideKeyword:
                 case SyntaxKind.ConstKeyword:
                 case SyntaxKind.DeclareKeyword:
                 case SyntaxKind.ReadonlyKeyword:

tests/baselines/reference/override16(target=es2015).js

@@ -0,0 +1,19 @@
+//// [override16.ts]
+class A {
+    foo?: string;
+}
+
+class B extends A {
+    override foo = "string";
+}
+
+
+//// [override16.js]
+class A {
+}
+class B extends A {
+    constructor() {
+        super(...arguments);
+        this.foo = "string";
+    }
+}

tests/baselines/reference/override16(target=es2015).symbols

@@ -0,0 +1,16 @@
+=== tests/cases/conformance/override/override16.ts ===
+class A {
+>A : Symbol(A, Decl(override16.ts, 0, 0))
+
+    foo?: string;
+>foo : Symbol(A.foo, Decl(override16.ts, 0, 9))
+}
+
+class B extends A {
+>B : Symbol(B, Decl(override16.ts, 2, 1))
+>A : Symbol(A, Decl(override16.ts, 0, 0))
+
+    override foo = "string";
+>foo : Symbol(B.foo, Decl(override16.ts, 4, 19))
+}
+

tests/baselines/reference/override16(target=es2015).types

@@ -0,0 +1,17 @@
+=== tests/cases/conformance/override/override16.ts ===
+class A {
+>A : A
+
+    foo?: string;
+>foo : string
+}
+
+class B extends A {
+>B : B
+>A : A
+
+    override foo = "string";
+>foo : string
+>"string" : "string"
+}
+

tests/baselines/reference/override16(target=esnext).js

@@ -0,0 +1,17 @@
+//// [override16.ts]
+class A {
+    foo?: string;
+}
+
+class B extends A {
+    override foo = "string";
+}
+
+
+//// [override16.js]
+class A {
+    foo;
+}
+class B extends A {
+    foo = "string";
+}

tests/baselines/reference/override16(target=esnext).symbols

@@ -0,0 +1,16 @@
+=== tests/cases/conformance/override/override16.ts ===
+class A {
+>A : Symbol(A, Decl(override16.ts, 0, 0))
+
+    foo?: string;
+>foo : Symbol(A.foo, Decl(override16.ts, 0, 9))
+}
+
+class B extends A {
+>B : Symbol(B, Decl(override16.ts, 2, 1))
+>A : Symbol(A, Decl(override16.ts, 0, 0))
+
+    override foo = "string";
+>foo : Symbol(B.foo, Decl(override16.ts, 4, 19))
+}
+

tests/baselines/reference/override16(target=esnext).types

@@ -0,0 +1,17 @@
+=== tests/cases/conformance/override/override16.ts ===
+class A {
+>A : A
+
+    foo?: string;
+>foo : string
+}
+
+class B extends A {
+>B : B
+>A : A
+
+    override foo = "string";
+>foo : string
+>"string" : "string"
+}
+

tests/baselines/reference/override16.js

@@ -0,0 +1,17 @@
+//// [override16.ts]
+class A {
+    foo?: string;
+}
+
+class B extends A {
+    override foo = "string";
+}
+
+
+//// [override16.js]
+class A {
+    foo;
+}
+class B extends A {
+    foo = "string";
+}

tests/baselines/reference/override16.symbols

@@ -0,0 +1,16 @@
+=== tests/cases/conformance/override/override16.ts ===
+class A {
+>A : Symbol(A, Decl(override16.ts, 0, 0))
+
+    foo?: string;
+>foo : Symbol(A.foo, Decl(override16.ts, 0, 9))
+}
+
+class B extends A {
+>B : Symbol(B, Decl(override16.ts, 2, 1))
+>A : Symbol(A, Decl(override16.ts, 0, 0))
+
+    override foo = "string";
+>foo : Symbol(B.foo, Decl(override16.ts, 4, 19))
+}
+

tests/baselines/reference/override16.types

@@ -0,0 +1,17 @@
+=== tests/cases/conformance/override/override16.ts ===
+class A {
+>A : A
+
+    foo?: string;
+>foo : string
+}
+
+class B extends A {
+>B : B
+>A : A
+
+    override foo = "string";
+>foo : string
+>"string" : "string"
+}
+

tests/baselines/reference/override17(target=es2015).js

@@ -0,0 +1,45 @@
+//// [override17.ts]
+class A {
+    public m1(): number {
+        return 0;
+    }
+
+    public m2(): number {
+        return 0;
+    }
+
+    public m3(): void {}
+}
+
+class B extends A {
+    override m1() {
+        return 10;
+    }
+
+    override m2(): number {
+        return 30;
+    }
+
+    override m3(): void {}
+}
+
+
+//// [override17.js]
+class A {
+    m1() {
+        return 0;
+    }
+    m2() {
+        return 0;
+    }
+    m3() { }
+}
+class B extends A {
+    m1() {
+        return 10;
+    }
+    m2() {
+        return 30;
+    }
+    m3() { }
+}

tests/baselines/reference/override17(target=es2015).symbols

@@ -0,0 +1,40 @@
+=== tests/cases/conformance/override/override17.ts ===
+class A {
+>A : Symbol(A, Decl(override17.ts, 0, 0))
+
+    public m1(): number {
+>m1 : Symbol(A.m1, Decl(override17.ts, 0, 9))
+
+        return 0;
+    }
+
+    public m2(): number {
+>m2 : Symbol(A.m2, Decl(override17.ts, 3, 5))
+
+        return 0;
+    }
+
+    public m3(): void {}
+>m3 : Symbol(A.m3, Decl(override17.ts, 7, 5))
+}
+
+class B extends A {
+>B : Symbol(B, Decl(override17.ts, 10, 1))
+>A : Symbol(A, Decl(override17.ts, 0, 0))
+
+    override m1() {
+>m1 : Symbol(B.m1, Decl(override17.ts, 12, 19))
+
+        return 10;
+    }
+
+    override m2(): number {
+>m2 : Symbol(B.m2, Decl(override17.ts, 15, 5))
+
+        return 30;
+    }
+
+    override m3(): void {}
+>m3 : Symbol(B.m3, Decl(override17.ts, 19, 5))
+}
+

tests/baselines/reference/override17(target=es2015).types

@@ -0,0 +1,44 @@
+=== tests/cases/conformance/override/override17.ts ===
+class A {
+>A : A
+
+    public m1(): number {
+>m1 : () => number
+
+        return 0;
+>0 : 0
+    }
+
+    public m2(): number {
+>m2 : () => number
+
+        return 0;
+>0 : 0
+    }
+
+    public m3(): void {}
+>m3 : () => void
+}
+
+class B extends A {
+>B : B
+>A : A
+
+    override m1() {
+>m1 : () => number
+
+        return 10;
+>10 : 10
+    }
+
+    override m2(): number {
+>m2 : () => number
+
+        return 30;
+>30 : 30
+    }
+
+    override m3(): void {}
+>m3 : () => void
+}
+

tests/baselines/reference/override17(target=esnext).js

@@ -0,0 +1,45 @@
+//// [override17.ts]
+class A {
+    public m1(): number {
+        return 0;
+    }
+
+    public m2(): number {
+        return 0;
+    }
+
+    public m3(): void {}
+}
+
+class B extends A {
+    override m1() {
+        return 10;
+    }
+
+    override m2(): number {
+        return 30;
+    }
+
+    override m3(): void {}
+}
+
+
+//// [override17.js]
+class A {
+    m1() {
+        return 0;
+    }
+    m2() {
+        return 0;
+    }
+    m3() { }
+}
+class B extends A {
+    m1() {
+        return 10;
+    }
+    m2() {
+        return 30;
+    }
+    m3() { }
+}

tests/baselines/reference/override17(target=esnext).symbols

@@ -0,0 +1,40 @@
+=== tests/cases/conformance/override/override17.ts ===
+class A {
+>A : Symbol(A, Decl(override17.ts, 0, 0))
+
+    public m1(): number {
+>m1 : Symbol(A.m1, Decl(override17.ts, 0, 9))
+
+        return 0;
+    }
+
+    public m2(): number {
+>m2 : Symbol(A.m2, Decl(override17.ts, 3, 5))
+
+        return 0;
+    }
+
+    public m3(): void {}
+>m3 : Symbol(A.m3, Decl(override17.ts, 7, 5))
+}
+
+class B extends A {
+>B : Symbol(B, Decl(override17.ts, 10, 1))
+>A : Symbol(A, Decl(override17.ts, 0, 0))
+
+    override m1() {
+>m1 : Symbol(B.m1, Decl(override17.ts, 12, 19))
+
+        return 10;
+    }
+
+    override m2(): number {
+>m2 : Symbol(B.m2, Decl(override17.ts, 15, 5))
+
+        return 30;
+    }
+
+    override m3(): void {}
+>m3 : Symbol(B.m3, Decl(override17.ts, 19, 5))
+}
+