Method call acting unexpectedly like an l-value

Question

Can anybody explain why this code compiles:

typedef struct longlong
{
  unsigned long low;
  long high;
}
longlong;

typedef longlong Foo;    

struct FooStr         


        

Answer 1

Reasons for this behavior were described in other answers.

One way to avoid this behavior would be qualifying your return type with const:

struct FooStruct
{
    ...
    const Foo GetBar() {return bar;}
};

You cannot assign values to const objects, so the compiler will complain.