tests/cases/compiler/methodInAmbientClass1.ts(2,20): error TS1037: A function implementation cannot be declared in an ambient context. tests/cases/compiler/methodInAmbientClass1.ts(2,12): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement. ==== tests/cases/compiler/methodInAmbientClass1.ts (2 errors) ==== declare class Foo { fn(): boolean { ~ !!! error TS1037: A function implementation cannot be declared in an ambient context. ~~~~~~~ !!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement. } }