Cherry-pick PR #45352 into release-4.4 (#45384)

Component commits:
58a924d fix(45345): throw an error on overridden member that is defined in multiple interfaces

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

src/compiler/checker.ts

@@ -37687,8 +37687,8 @@ namespace ts {
                             error(member, Diagnostics.This_member_cannot_have_an_override_modifier_because_it_is_not_declared_in_the_base_class_0_Did_you_mean_1, baseClassName, symbolToString(suggestion)) :
                             error(member, Diagnostics.This_member_cannot_have_an_override_modifier_because_it_is_not_declared_in_the_base_class_0, baseClassName);
                     }
-                    else if (prop && baseProp?.valueDeclaration && compilerOptions.noImplicitOverride && !nodeInAmbientContext) {
-                        const baseHasAbstract = hasAbstractModifier(baseProp.valueDeclaration);
+                    else if (prop && baseProp?.declarations && compilerOptions.noImplicitOverride && !nodeInAmbientContext) {
+                        const baseHasAbstract = some(baseProp.declarations, d => hasAbstractModifier(d));
                         if (hasOverride) {
                             return;
                         }

tests/baselines/reference/override20.errors.txt

@@ -0,0 +1,41 @@
+tests/cases/conformance/override/override20.ts(25,5): error TS4114: This member must have an 'override' modifier because it overrides a member in the base class 'I1 & I2'.
+tests/cases/conformance/override/override20.ts(28,5): error TS4114: This member must have an 'override' modifier because it overrides a member in the base class 'I1 & I2'.
+
+
+==== tests/cases/conformance/override/override20.ts (2 errors) ====
+    const Foo: C1 & C2 =
+        class {
+            m1() { }
+            m2() { }
+        }
+
+    interface I1 {
+        m1(): void;
+    }
+
+    interface I2 {
+        m1(): void;
+        m2(): void;
+    }
+
+    interface C1 {
+        new(...args: any[]): I1;
+    }
+
+    interface C2 {
+        new(...args: any[]): I2;
+    }
+
+    export class Bar extends Foo {
+        m1() {
+        ~~
+!!! error TS4114: This member must have an 'override' modifier because it overrides a member in the base class 'I1 & I2'.
+            super.m1();
+        }
+        m2() {
+        ~~
+!!! error TS4114: This member must have an 'override' modifier because it overrides a member in the base class 'I1 & I2'.
+            super.m2();
+        }
+    }
+

tests/baselines/reference/override20.js

@@ -0,0 +1,47 @@
+//// [override20.ts]
+const Foo: C1 & C2 =
+    class {
+        m1() { }
+        m2() { }
+    }
+
+interface I1 {
+    m1(): void;
+}
+
+interface I2 {
+    m1(): void;
+    m2(): void;
+}
+
+interface C1 {
+    new(...args: any[]): I1;
+}
+
+interface C2 {
+    new(...args: any[]): I2;
+}
+
+export class Bar extends Foo {
+    m1() {
+        super.m1();
+    }
+    m2() {
+        super.m2();
+    }
+}
+
+
+//// [override20.js]
+const Foo = class {
+    m1() { }
+    m2() { }
+};
+export class Bar extends Foo {
+    m1() {
+        super.m1();
+    }
+    m2() {
+        super.m2();
+    }
+}

tests/baselines/reference/override20.symbols

@@ -0,0 +1,67 @@
+=== tests/cases/conformance/override/override20.ts ===
+const Foo: C1 & C2 =
+>Foo : Symbol(Foo, Decl(override20.ts, 0, 5))
+>C1 : Symbol(C1, Decl(override20.ts, 13, 1))
+>C2 : Symbol(C2, Decl(override20.ts, 17, 1))
+
+    class {
+        m1() { }
+>m1 : Symbol(Foo.m1, Decl(override20.ts, 1, 11))
+
+        m2() { }
+>m2 : Symbol(Foo.m2, Decl(override20.ts, 2, 16))
+    }
+
+interface I1 {
+>I1 : Symbol(I1, Decl(override20.ts, 4, 5))
+
+    m1(): void;
+>m1 : Symbol(I1.m1, Decl(override20.ts, 6, 14))
+}
+
+interface I2 {
+>I2 : Symbol(I2, Decl(override20.ts, 8, 1))
+
+    m1(): void;
+>m1 : Symbol(I2.m1, Decl(override20.ts, 10, 14))
+
+    m2(): void;
+>m2 : Symbol(I2.m2, Decl(override20.ts, 11, 15))
+}
+
+interface C1 {
+>C1 : Symbol(C1, Decl(override20.ts, 13, 1))
+
+    new(...args: any[]): I1;
+>args : Symbol(args, Decl(override20.ts, 16, 8))
+>I1 : Symbol(I1, Decl(override20.ts, 4, 5))
+}
+
+interface C2 {
+>C2 : Symbol(C2, Decl(override20.ts, 17, 1))
+
+    new(...args: any[]): I2;
+>args : Symbol(args, Decl(override20.ts, 20, 8))
+>I2 : Symbol(I2, Decl(override20.ts, 8, 1))
+}
+
+export class Bar extends Foo {
+>Bar : Symbol(Bar, Decl(override20.ts, 21, 1))
+>Foo : Symbol(Foo, Decl(override20.ts, 0, 5))
+
+    m1() {
+>m1 : Symbol(Bar.m1, Decl(override20.ts, 23, 30))
+
+        super.m1();
+>super.m1 : Symbol(m1, Decl(override20.ts, 6, 14), Decl(override20.ts, 10, 14))
+>m1 : Symbol(m1, Decl(override20.ts, 6, 14), Decl(override20.ts, 10, 14))
+    }
+    m2() {
+>m2 : Symbol(Bar.m2, Decl(override20.ts, 26, 5))
+
+        super.m2();
+>super.m2 : Symbol(I2.m2, Decl(override20.ts, 11, 15))
+>m2 : Symbol(I2.m2, Decl(override20.ts, 11, 15))
+    }
+}
+

tests/baselines/reference/override20.types

@@ -0,0 +1,61 @@
+=== tests/cases/conformance/override/override20.ts ===
+const Foo: C1 & C2 =
+>Foo : C1 & C2
+
+    class {
+>class {        m1() { }        m2() { }    } : typeof Foo
+
+        m1() { }
+>m1 : () => void
+
+        m2() { }
+>m2 : () => void
+    }
+
+interface I1 {
+    m1(): void;
+>m1 : () => void
+}
+
+interface I2 {
+    m1(): void;
+>m1 : () => void
+
+    m2(): void;
+>m2 : () => void
+}
+
+interface C1 {
+    new(...args: any[]): I1;
+>args : any[]
+}
+
+interface C2 {
+    new(...args: any[]): I2;
+>args : any[]
+}
+
+export class Bar extends Foo {
+>Bar : Bar
+>Foo : I1 & I2
+
+    m1() {
+>m1 : () => void
+
+        super.m1();
+>super.m1() : void
+>super.m1 : (() => void) & (() => void)
+>super : I1 & I2
+>m1 : (() => void) & (() => void)
+    }
+    m2() {
+>m2 : () => void
+
+        super.m2();
+>super.m2() : void
+>super.m2 : () => void
+>super : I1 & I2
+>m2 : () => void
+    }
+}
+

tests/cases/conformance/override/override20.ts

@@ -0,0 +1,34 @@
+// @target: esnext
+// @noImplicitOverride: true
+
+const Foo: C1 & C2 =
+    class {
+        m1() { }
+        m2() { }
+    }
+
+interface I1 {
+    m1(): void;
+}
+
+interface I2 {
+    m1(): void;
+    m2(): void;
+}
+
+interface C1 {
+    new(...args: any[]): I1;
+}
+
+interface C2 {
+    new(...args: any[]): I2;
+}
+
+export class Bar extends Foo {
+    m1() {
+        super.m1();
+    }
+    m2() {
+        super.m2();
+    }
+}

tests/cases/fourslash/codeFixOverrideModifier22.ts

@@ -0,0 +1,41 @@
+/// <reference path='fourslash.ts' />
+
+// @noImplicitOverride: true
+
+////const Foo: C1 & C2 =
+////    class {
+////        m1() { }
+////        m2() { }
+////    }
+////
+////interface I1 {
+////    m1(): void;
+////}
+////
+////interface I2 {
+////    m1(): void;
+////    m2(): void;
+////}
+////
+////interface C1 {
+////    new(...args: any[]): I1;
+////}
+////
+////interface C2 {
+////    new(...args: any[]): I2;
+////}
+////
+////class Bar extends Foo {
+////    [|m1()|] {
+////        super.m1();
+////    }
+////    m2() {
+////        super.m2();
+////    }
+////}
+
+verify.codeFix({
+    description: "Add 'override' modifier",
+    newRangeContent: "override m1()",
+    index: 0
+})