C# 7.1 introduces a new feature called "Default Literals" that allows new default expressions.
// instead of writing
Foo x = default(Foo);
// we can just write
Foo x = default;
For Nullable<T> types, the default value is null, and with the usual usage this works as expected:
int? x = default(int?); // x is null
int? x = default; // x is null
However, when I try to use the new default literal as an optional argument (parameter) of a function, it's not working as expected:
static void Foo(int? x = default(int?))
{
// x is null
}
static void Foo(int? x = default)
{
// x is 0 !!!
}
To me, this behavior is unexpected and looks like a bug in the compiler.
Can anybody confirm the bug, or explain this behavior?
