[forwarded from http://bugs.debian.org/373909]
Rechecked with 4.1.2 20060630 and 4.2.0
The following code generates the g++ compiler error:
14: error: expected constructor, destructor, or type conversion
before Outer
template <typename T>
class Outer
{
public:
class Inner
{
};
Inner get() const;
};
template <typename T>
Outer<T>::Inner
Outer<T>::get() const // <-- this is line 14
{
return Inner();
}
If the function get() is placed inside the template class Outer, no error is
reported. E.g.,
template <typename T>
class Outer
{
public:
class Inner
{
};
Inner get() const
{
return Inner();
}
};
An external definition compiles well if the class Inner is explicitly defined
as a template class (even though no template parameters are required). E.g.,
template <typename T>
class Outer
{
public:
template <typename U>
class Inner
{
};
Inner<T> get() const;
};
template <typename T>
Outer<T>::Inner<T>
Outer<T>::get() const
{
return Inner<T>();
}
Moreover, the first source, producing a compilation error with g++ was also
offered to the intel C++ compiler, where it compiled flawlessly. Here is a
transcript of the issued commands, illustrating the difference:
[EMAIL PROTECTED]:~/programming/C++$ g++ -c -Wall demo1.cxx
demo1.cxx:14: error: expected constructor, destructor, or type
conversion before ?Outer?
[EMAIL PROTECTED]:~/programming/C++$ icc -c -Wall demo1.cxx
[EMAIL PROTECTED]:~/programming/C++$
My considerations for filing a bug report were:
* g++ produces a compilation error where icc doesn't;
* g++'s compilation error is only produced when the template function is
defined outside of its template class;
* the reported error message is rather cryptic, given the nature of the
source, suggesting confusion on the part of the compiler.
Of course, g++ might offer a more rigid implementation of the C++ standard at
this point. However, I couldn't find a clear indication that the external
function implementation violates the standard. Hence the bug report.
--
Summary: template function returning nested class fails to
compile when defined outside of its class
Product: gcc
Version: 4.1.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: debian-gcc at lists dot debian dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28317
