can't use typedef of nested class in template class

[Frank Bergemann]

following doesn't work (gcc-3.4.4)

cat test2.h

template <class Result>
class MyClass
{
private:
class NestedClass
{
public:
typedef int SubType;
} ;
NestedClass::SubType element;
} ;

cat test2.cc

#include "test2.h"

/usr/local/gcc-3.4.4/bin/g++ -c test2.cc

In file included from test2.cc:1:
test2.h:12: error: expected `;' before "element"


When i move NestedClass out, it works:

|padsol05 371> cat test2.h
class NestedClass
{
public:
typedef int SubType;
} ;

template <class Result>
class MyClass
{
private:
NestedClass::SubType element;
} ;


???

 

[Ian Collins]

following doesn't work (gcc-3.4.4)

template <class Result>
class MyClass
{
private:
class NestedClass
{
public:
typedef int SubType;
} ;
NestedClass::SubType element;

You have to tell the compiler NestedClass::SubType is a type:

typename NestedClass::SubType element;

 

[Jonathan Mcdougall]

You have to tell the compiler NestedClass::SubType is a type:

typename NestedClass::SubType element;

The given example works in Comeau and the FAQ only talks about
nested classes defined in a base class (35.18). As far as I
know, because NestedClass is not a template, there is no need
to do this, although I may be wrong.

 

[James Kanze]

You have to tell the compiler NestedClass::SubType is a type:

typename NestedClass::SubType element;

You shouldn't have to. NestedClass is not a dependent type, but
rather a locally defined type, so the compiler knows what is in
it, even without instantiating the template.

 

[Frank Bergemann]

- thanks, Ian!
it worked this way.

rgds!

Frank

 

[Ian Collins]

You shouldn't have to. NestedClass is not a dependent type, but
rather a locally defined type, so the compiler knows what is in
it, even without instantiating the template.

I know, but gcc thinks otherwise!