Add tests

Author: ahejlsberg

tests/cases/compiler/strictFunctionTypes1.ts

@@ -27,3 +27,27 @@ const x11 = f3(never, fo, fx);  // "def"
 
 declare function foo<T>(a: ReadonlyArray<T>): T;
 let x = foo([]);  // never
+
+// Modified repros from #26127
+
+interface A { a: string }
+interface B extends A { b: string }
+
+declare function acceptUnion(x: A | number): void;
+declare function acceptA(x: A): void;
+
+declare let a: A;
+declare let b: B;
+declare let never: never;
+
+declare function coAndContra<T>(value: T, func: (t: T) => void): T;
+
+const t1: A = coAndContra(a, acceptUnion);
+const t2: B = coAndContra(b, acceptA);
+const t3: A = coAndContra(never, acceptA);
+
+declare function coAndContraArray<T>(value: T[], func: (t: T) => void): T[];
+
+const t4: A[] = coAndContraArray([a], acceptUnion);
+const t5: B[] = coAndContraArray([b], acceptA);
+const t6: A[] = coAndContraArray([], acceptA);