anchor.diff:    // [analyzer] COMPILE_TIME_ERROR.AMBIGUOUS_EXTENSION_MEMBER_ACCESS
     // [cfe] unspecified
   
  +  c1b.m1 += 0;
  +  //  ^^
  +  // [analyzer] COMPILE_TIME_ERROR.AMBIGUOUS_EXTENSION_MEMBER_ACCESS
  +  // [cfe] unspecified
  +
  +  c1b.m1++;
  +  //  ^^
  +  // [analyzer] COMPILE_TIME_ERROR.AMBIGUOUS_EXTENSION_MEMBER_ACCESS
  +  // [cfe] unspecified
  +
     c1b.m2;
     //  ^^
     // [analyzer] COMPILE_TIME_ERROR.AMBIGUOUS_EXTENSION_MEMBER_ACCESS
     // [cfe] unspecified
   
  -  c1b.m2 = 0;
  -  //  ^^
  -  // [analyzer] COMPILE_TIME_ERROR.AMBIGUOUS_EXTENSION_MEMBER_ACCESS
  +
  +  c1b[0];
  +  //  ^^
  +  // [analyzer] unspecified
  +  // [cfe] unspecified
  +
  +  c1b[0] = 0;
  +  //  ^^
  +  // [analyzer] unspecified
  +  // [cfe] unspecified
  +
  +  c1b[0] += 0;
  +  //  ^^
  +  // [analyzer] unspecified
  +  // [cfe] unspecified
  +
  +  c1b[0]++;
  +  //  ^^
  +  // [analyzer] unspecified
     // [cfe] unspecified
   }
   
  
positive.code: extension E1A<T> on C1<T> {
    int get m1 => 0;
    void set m2(int x) {}
  }
  
  extension E1B on C1<Object> {
    void set m1(int x) {}
    int get m2 => 0;
  }
  
  void test1() {
  
negative.code:   // [cfe] unspecified
  
    c0.m1 += 0;
    // ^^
    // [analyzer] STATIC_WARNING.ASSIGNMENT_TO_FINAL_NO_SETTER
    // [cfe] unspecified
  
    c0.m1++;
    // ^^
    // [analyzer] STATIC_WARNING.ASSIGNMENT_TO_FINAL_NO_SETTER
    // [cfe] unspecified
  
    c0.m2 = 0;
    c0.m2;
    // ^^
    // [analyzer] STATIC_TYPE_WARNING.UNDEFINED_GETTER
    // [cfe] unspecified
    c0.m2 += 0;
    // ^^
    // [analyzer] STATIC_TYPE_WARNING.UNDEFINED_GETTER
    // [cfe] unspecified
    c0.m2++;
    // ^^
    // [analyzer] STATIC_TYPE_WARNING.UNDEFINED_GETTER
    // [cfe] unspecified
  
    E0(c0).m2;
  
    c0[0];
    c0[0] = 0;
    // ^^^^^^
    // [analyzer] unspecified
    // [cfe] unspecified
    E0(c0)[0];
    // ^^^^^^
    // [analyzer] unspecified
    // [cfe] unspecified
    E0(c0)[0] = 0;
  
    c0[0] += 0;
    // ^^^^^^
    // [analyzer] unspecified
    // [cfe] unspecified
    c0[0]++;
    // ^^^^^^
    // [analyzer] unspecified
    // [cfe] unspecified
  
    E0(c0)[0] += 0;
    // ^^^^^^
    // [analyzer] unspecified
    // [cfe] unspecified
    E0(c0)[0]++;
    // ^^^^^^
    // [analyzer] unspecified
    // [cfe] unspecified
  }
  
  // Conflicting extensions.
  