tests/cases/compiler/overloadresolutionWithConstraintCheckingDeferred.ts(14,5): error TS2322: Type 'string' is not assignable to type 'number'. tests/cases/compiler/overloadresolutionWithConstraintCheckingDeferred.ts(14,37): error TS2345: Argument of type 'D' is not assignable to parameter of type 'A'. Property 'x' is missing in type 'D'. tests/cases/compiler/overloadresolutionWithConstraintCheckingDeferred.ts(16,5): error TS2322: Type 'string' is not assignable to type 'number'. tests/cases/compiler/overloadresolutionWithConstraintCheckingDeferred.ts(16,38): error TS2344: Type 'D' does not satisfy the constraint 'A'. tests/cases/compiler/overloadresolutionWithConstraintCheckingDeferred.ts(18,27): error TS2345: Argument of type '(x: D) => G' is not assignable to parameter of type '(x: B) => any'. Types of parameters 'x' and 'x' are incompatible. Type 'D' is not assignable to type 'B'. Property 'x' is missing in type 'D'. tests/cases/compiler/overloadresolutionWithConstraintCheckingDeferred.ts(19,14): error TS2344: Type 'D' does not satisfy the constraint 'A'. ==== tests/cases/compiler/overloadresolutionWithConstraintCheckingDeferred.ts (6 errors) ==== interface A { x } interface B { x; y } interface C { z } interface D { q } class G { constructor(x: T) { } } declare function foo(arg: (x: D) => number): string; declare function foo(arg: (x: C) => any): string; declare function foo(arg: (x: B) => any): number; var result: number = foo(x => new G(x)); // x has type D, new G(x) fails, so first overload is picked. ~~~~~~ !!! error TS2322: Type 'string' is not assignable to type 'number'. ~ !!! error TS2345: Argument of type 'D' is not assignable to parameter of type 'A'. !!! error TS2345: Property 'x' is missing in type 'D'. var result2: number = foo(x => new G(x)); // x has type D, new G(x) fails, so first overload is picked. ~~~~~~~ !!! error TS2322: Type 'string' is not assignable to type 'number'. ~~~~~~~~ !!! error TS2344: Type 'D' does not satisfy the constraint 'A'. var result3: string = foo(x => { // x has type D ~~~~~~~~~~~~~~~~~~~~~~ var y: G; // error that D does not satisfy constraint, y is of type G, entire call to foo is an error ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~ !!! error TS2344: Type 'D' does not satisfy the constraint 'A'. return y; ~~~~~~~~~~~~~ }); ~ !!! error TS2345: Argument of type '(x: D) => G' is not assignable to parameter of type '(x: B) => any'. !!! error TS2345: Types of parameters 'x' and 'x' are incompatible. !!! error TS2345: Type 'D' is not assignable to type 'B'. !!! error TS2345: Property 'x' is missing in type 'D'.