tests/language_2/nnbd/resolution/question_dot_index_produces_nullable_type_test.dart

// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

// SharedOptions=--enable-experiment=non-nullable

void main() {}

void f1(NotGeneric x) {
  x[0] + 1; //# 01: ok
  x[0] = 1; //# 02: ok
  useNonNullable(x[0] = 1); //# 03: ok
  x[0] += 1; //# 04: ok
  useNonNullable(x[0] += 1); //# 05: ok
}

void f2(NotGeneric? x) {
  x?.[0] + 1; //# 06: compile-time error
  x?.[0] = 1; //# 07: ok
  useNonNullable(x?.[0] = 1); //# 08: compile-time error
  x?.[0] += 1; //# 09: ok
  useNonNullable(x?.[0] += 1); //# 10: compile-time error
}

void f3<T extends num>(Generic<T>? x) {
  x?.[0] + 1; //# 11: compile-time error
}

void f4<T extends num>(Generic<T?> x) {
  x[0] + 1; //# 12: compile-time error
}

class NotGeneric {
  int operator[](int index) => throw 'unreachable';
  void operator[]=(int index, int value) => throw 'unreachable';
}

class Generic<T> {
  T operator[](int index) => throw 'unreachable';
  void operator[]=(int index, T value) => throw 'unreachable';
}

void useNonNullable(int a) {}