Glvalue real examples and explanation?

Question

I know what 'xvalues', 'prvalues', 'rvalues' and 'lvalues' are, how they are helpful and I've seen real examples of them. But I've never understand what a 'glvalue' is, and how it co-operate with the others. I've searched everywhere but with no-luck even in the latest standard paper it was barely noticed. Can somebody explains it to me and show some examples?

Note that this is not a duplicate of this, as even there nobody gave an example of 'glvalue'. Here too. It was only barely mentioned like this:

A glvalue (“generalized” lvalue) is an lvalue or an xvalue.

Answer 1

A glvalue is anything that isn't a prvalue. Examples are names of entities, or expressions that have reference type (regardless of the kind of the reference).

int i;
int* p = &i;
int& f();
int&& g();

int h();

h() // prvalue
g() // glvalue (xvalue)
f() // glvalue (lvalue)
i   // glvalue (lvalue)
*p  // glvalue (lvalue)

std::move(i)  // glvalue (xvalue)

As the quote in your question clearly states, the category glvalue includes all xvalues and lvalues. lvalues, xvalues and prvalues are complementary categories:

Every expression belongs to exactly one of the fundamental classifications in this taxonomy: lvalue, xvalue, or prvalue.

You should be familiar with lvalues. Now consider what xvalues are, [expr]/6:

[ Note: An expression is an xvalue if it is:

• the result of calling a function, whether implicitly or explicitly, whose return type is an rvalue reference to object type,
• a cast to an rvalue reference to object type,
• a class member access expression designating a non-static data member of non-reference type in which the object expression is an xvalue, or
• a .* pointer-to-member expression in which the first operand is an xvalue and the second operand is a pointer to data member.

[…] — end note ]

So, roughly speaking, you could think of glvalues as
"All lvalues plus expressions involving rvalue references".
We use it to describe expressions that refer to objects rather than "being" those objects.