tests/cases/compiler/constraints0.ts(14,9): error TS2344: Type 'B' does not satisfy the constraint 'A'. Property 'a' is missing in type 'B'. ==== tests/cases/compiler/constraints0.ts (1 errors) ==== interface A { a: number; } interface B { b: string; } interface C { x: T; } var v1: C; // should work var v2: C; // should not work ~~~~ !!! error TS2344: Type 'B' does not satisfy the constraint 'A'. !!! error TS2344: Property 'a' is missing in type 'B'. var y = v1.x.a; // 'a' should be of type 'number'