Re: Access of a local class in a template function to a static
variable
On Feb 3, 2:36 pm, Michael DOUBEZ <michael.dou...@free.fr> wrote:
ym...@hotmail.com wrote:
I have the following code which compiles and runs fine on
GCC 4.3.2:
[snip]
But when I do the same thing with a templated type instead
of 'int', the code compiles but I get a link error:
//--------------------------------------------------------
template<typename T>
struct A {virtual T getnum()=0;};
template<typename T>
A<T>* func(T numin) {
static T num;
num=numin;
struct B : public A<T> {
T getnum(){
delete this;
return num; // <----- link error: undefined reference
to 'num'
}
};
return new B();
}
int main() {
func(3)->getnum();
return 0;
}
//--------------------------------------------------------
Is this a compiler bug, or is this actually not supposed to
work with templates?
This is a compiler bug. AFAIK the program is well formed
Comeau compiles it without problem.
Does it link as well? His problem only occured when linking.
According to the standard (at least as far as I can tell), it's
legal, and any conforming compiler should be able to handle it.
The basic rule (in =A79.8) says that "Declarations in a local
class can use only type names, static variables, extern
variables and functions, and enumerators from the enclosing
scope", and I can't find anything which would change this in a
template. (There are a few special rules for locally declared
names in templates, but either they apply only to class
templates, or they only concern the template parameters
themselves.)
--
James Kanze (GABI Software) email:james.kanze@gmail.com
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