11
Classes
[class]
11.6
Local class declarations
[class.local]
1
#
A class can be declared within a function definition; such a class is called a
local class
.
[
Note
1
:
A declaration in a local class cannot odr-use (
[basic.
def.
odr]
) a local entity from an enclosing scope
.
—
end note
]
[
Example
1
:
int
x;
void
f
(
)
{
static
int
s;
int
x;
const
int
N
=
5
;
extern
int
q
(
)
;
int
arr
[
2
]
;
auto
[
y, z
]
=
arr;
struct
local
{
int
g
(
)
{
return
x;
}
// error: odr-use of non-odr-usable variable
x
int
h
(
)
{
return
s;
}
// OK
int
k
(
)
{
return
::
x;
}
// OK
int
l
(
)
{
return
q
(
)
;
}
// OK
int
m
(
)
{
return
N;
}
// OK, not an odr-use
int
*
n
(
)
{
return
&
N;
}
// error: odr-use of non-odr-usable variable
N
int
p
(
)
{
return
y;
}
// error: odr-use of non-odr-usable structured binding
y
}
;
}
local
*
p
=
0
;
// error:
local
not found
—
end example
]
2
#
An enclosing function has no special access to members of the local class; it obeys the usual access rules (
[class.
access]
)
.
Member functions of a local class shall be defined within their class definition, if they are defined at all
.
3
#
A class nested within a local class is a local class
.
A member of a local class
X
shall be declared only in the definition of
X
or, if the member is a nested class, in the nearest enclosing block scope of
X
.
4
#
[
Note
2
:
A local class cannot have static data members (
[class.
static.
data]
)
.
—
end note
]