C++ static member function reported as undefined references by linker?

C++ static member function reported as undefined references by linker?

[David Cespedes]

Can you help with this issue, in regards to C++ static member functions and why they are reported as undefined references by the linker?
 
Please see attached email trail!
 
Best Regards
Daveed
________________________________________
From: Paul
Sent: Thursday, October 27, 2005 10:40 AM
To: David Cespedes
Subject: RE: Linux C++ implementation

I don't know enough about Linux/gcc to help.
static members are supposed to have external linkage--ARM Sec 9.4
 
________________________________________
From: David Cespedes  
Sent: Thursday, October 27, 2005 11:46 AM
To: Paul
Subject: RE: Linux C++ implementation
Yes, I did! I have a Sample.h for the definition and Sample.cpp where there is a void CSample::test(unsigned char foo) { ... } implementation.
 
The only work-around I found is to implement the method function in the definition .H file (inline it) and I must declare the static member as an "extern bool CSample::m_bState" in order to see it, from an outside scope.
 
________________________________________
From: Paul
Sent: Thursday, October 27, 2005 10:40 AM
To: David Cespedes
Subject: RE: Linux C++ implementation
 
Did you define (implement) the function somewhere?
gcc is a very good compiler, I'm sure it follows all the standards.
 
________________________________________
From: David Cespedes  
Sent: Thursday, October 27, 2005 11:02 AM
To: Paul 
Subject: Linux C++ implementation
Hi Paul!
 
Once again I see myself baffled by a C++ questions and you are my last source for an educated answer. Anyhow, I have just started developing under the Linux platform using the gcc 2.96; do not ask why that version I do not control it. 
 
So I am working along and, by now, C++ is supposed to be C++ on any platform, until I declare a static method function and member in a class; see sample code. When I do this, if I try to use the global scope CSample::Test(...), the linker tells me that the function is an undefined reference???
 
What happen here are? Did then gcc folks confuse the "C" vs. "C++" interpretation of a static scope? I need help...
 
class CSample 
{
public:
CSample();
~CSample();
static void test(unsigned char foo);
  
protected:
static bool m_bState;
};
 
Best regards,
 
________________________________________
David A. Cespedes
Chief Software Engineer - Manager
I/O Marine Imaging Systems Division
Office: 281.879.2171
 

Re: C++ static member function reported as undefined references by linker?

[corey taylor]

David,

  As far as I know, they only have external linkage if the class has
external linkage.

Corey

On 10/27/05, David Cespedes <David.Cespedes@i-o.com> wrote:
> Can you help with this issue, in regards to C++ static member functions and why they are reported as undefined references by the linker?
>
> Please see attached email trail!
>
> Best Regards
> Daveed
> ________________________________________
> From: Paul
> Sent: Thursday, October 27, 2005 10:40 AM
> To: David Cespedes
> Subject: RE: Linux C++ implementation
>
> I don't know enough about Linux/gcc to help.
> static members are supposed to have external linkage--ARM Sec 9.4
>
> ________________________________________
> From: David Cespedes
> Sent: Thursday, October 27, 2005 11:46 AM
> To: Paul
> Subject: RE: Linux C++ implementation
> Yes, I did! I have a Sample.h for the definition and Sample.cpp where there is a void CSample::test(unsigned char foo) { ... } implementation.
>
> The only work-around I found is to implement the method function in the definition .H file (inline it) and I must declare the static member as an "extern bool CSample::m_bState" in order to see it, from an outside scope.
>
> ________________________________________
> From: Paul
> Sent: Thursday, October 27, 2005 10:40 AM
> To: David Cespedes
> Subject: RE: Linux C++ implementation
>
> Did you define (implement) the function somewhere?
> gcc is a very good compiler, I'm sure it follows all the standards.
>
> ________________________________________
> From: David Cespedes
> Sent: Thursday, October 27, 2005 11:02 AM
> To: Paul
> Subject: Linux C++ implementation
> Hi Paul!
>
> Once again I see myself baffled by a C++ questions and you are my last source for an educated answer. Anyhow, I have just started developing under the Linux platform using the gcc 2.96; do not ask why that version I do not control it.
>
> So I am working along and, by now, C++ is supposed to be C++ on any platform, until I declare a static method function and member in a class; see sample code. When I do this, if I try to use the global scope CSample::Test(...), the linker tells me that the function is an undefined reference???
>
> What happen here are? Did then gcc folks confuse the "C" vs. "C++" interpretation of a static scope? I need help...
>
> class CSample
> {
> public:
> CSample();
> ~CSample();
> static void test(unsigned char foo);
>
> protected:
> static bool m_bState;
> };
>
> Best regards,
>
> ________________________________________
> David A. Cespedes
> Chief Software Engineer - Manager
> I/O Marine Imaging Systems Division
> Office: 281.879.2171
>
>

Re: C++ static member function reported as undefined references by linker?

[Nathan Sidwell]

David Cespedes wrote:
> Can you help with this issue, in regards to C++ static member functions and why they are reported as undefined references by the linker?
>  
> Please see attached email trail!

please provide a complete test case, I can't figure out from the email trail 
what you;re trying to compile.

nathan

-- 
Nathan Sidwell    ::   http://www.codesourcery.com   ::     CodeSourcery LLC
nathan@codesourcery.com    ::     http://www.planetfall.pwp.blueyonder.co.uk

Re: C++ static member function reported as undefined references by linker?

[corey taylor]

He was trying to use an old gcc version to compile some code that had
a global namespace declared class and static class method.

The issue was that the static class method wasn't given external
linkage in that version without declaring the class in a named
namespace.

For about a day, I mistakenly said it was appropriate behavior because
the class wasn't declared in a proper namespace, but after coming to
my senses and the spec, it clearly should have external linkage now
(2003 spec).

I gave him the work-a-round for that old gcc to simply declare the
class inside of a named namespace instead of global namespace.

corey

On 11/5/05, Nathan Sidwell <nathan@codesourcery.com> wrote:
> David Cespedes wrote:
> > Can you help with this issue, in regards to C++ static member functions and why they are reported as undefined references by the linker?
> >
> > Please see attached email trail!
>
> please provide a complete test case, I can't figure out from the email trail
> what you;re trying to compile.
>
> nathan
>
> --
> Nathan Sidwell    ::   http://www.codesourcery.com   ::     CodeSourcery LLC
> nathan@codesourcery.com    ::     http://www.planetfall.pwp.blueyonder.co.uk
>
>

Re: C++ static member function reported as undefined references by linker?

[corey taylor]

Hi David,

  I believe that I mispoke about part of it and the named class should
give external linkage to its members.

  Just a little too busy my apologies!

Corey

On 10/27/05, David Cespedes <David.Cespedes@i-o.com> wrote:
> I do not have the SPEC with me will have to check around! But you read
> it in;
>
> ARM (Annotated Reference Manual), Sec 9.4:
> "Static members of a global class have external linkage."
>
> Regards,
> Daveed

Re: C++ static member function reported as undefined references by linker?

[corey taylor]

I don't have that book and will have to wait for someone else to
comment on the passage.

Considering what the static member function is, it would seem logical
to default to internal linkage in accordance with other static
declarations.

corey

On 10/27/05, David Cespedes <David.Cespedes@i-o.com> wrote:
> If inside a namespace, yes. But not inside a class, unless the class is
> inside a namespace.
>
> See the ARM (Annotated Reference Manual), Sec 9.4:
> "Static members of a global class have external linkage."
>
> -----Original Message-----
> From: corey taylor [mailto:corey.taylor@gmail.com]
> Sent: Thursday, October 27, 2005 1:07 PM
> To: David Cespedes; gcc-help@gnu.org
> Subject: Re: C++ static member function reported as undefined references
> by linker?
>
> This is according to the C++ specification.  Check out section 3.5
> (Program and Linkage) of the 14882:2003 specification.
>
> Corey
>
> On 10/27/05, David Cespedes <David.Cespedes@i-o.com> wrote:
> > You are right, it worked. Is this an artifact of the gcc? I am nit
> sure
> > this is 100% compliant with the C++ spec. I see this as a work around,
> > thank you for all the help
> >
> > Regards
> > Daveed
> >
> > -----Original Message-----
> > From: corey taylor [mailto:corey.taylor@gmail.com]
> > Sent: Thursday, October 27, 2005 12:30 PM
> > To: David Cespedes
> > Subject: Re: C++ static member function reported as undefined
> references
> > by linker?
> >
> > You will automatically get external linkage when declared inside of a
> > named namespace.
> >
> > corey
> >
> > On 10/27/05, David Cespedes <David.Cespedes@i-o.com> wrote:
> > > Well show does a class have external linkage? I though this was the
> > > default? Please show me an example.
> > >
> > > Regards,
> > > Daveed
> > >
> > > -----Original Message-----
> > > From: corey taylor [mailto:corey.taylor@gmail.com]
> > > Sent: Thursday, October 27, 2005 11:40 AM
> > > To: David Cespedes
> > > Cc: gcc-help@gcc.gnu.org
> > > Subject: Re: C++ static member function reported as undefined
> > references
> > > by linker?
> > >
> > > David,
> > >
> > >   As far as I know, they only have external linkage if the class has
> > > external linkage.
> > >
> > > Corey
> > >
> > > On 10/27/05, David Cespedes <David.Cespedes@i-o.com> wrote:
> > > > Can you help with this issue, in regards to C++ static member
> > > functions and why they are reported as undefined references by the
> > > linker?
> > > >
> > > > Please see attached email trail!
> > > >
> > > > Best Regards
> > > > Daveed
> > > > ________________________________________
> > > > From: Paul
> > > > Sent: Thursday, October 27, 2005 10:40 AM
> > > > To: David Cespedes
> > > > Subject: RE: Linux C++ implementation
> > > >
> > > > I don't know enough about Linux/gcc to help.
> > > > static members are supposed to have external linkage--ARM Sec 9.4
> > > >
> > > > ________________________________________
> > > > From: David Cespedes
> > > > Sent: Thursday, October 27, 2005 11:46 AM
> > > > To: Paul
> > > > Subject: RE: Linux C++ implementation
> > > > Yes, I did! I have a Sample.h for the definition and Sample.cpp
> > where
> > > there is a void CSample::test(unsigned char foo) { ... }
> > implementation.
> > > >
> > > > The only work-around I found is to implement the method function
> in
> > > the definition .H file (inline it) and I must declare the static
> > member
> > > as an "extern bool CSample::m_bState" in order to see it, from an
> > > outside scope.
> > > >
> > > > ________________________________________
> > > > From: Paul
> > > > Sent: Thursday, October 27, 2005 10:40 AM
> > > > To: David Cespedes
> > > > Subject: RE: Linux C++ implementation
> > > >
> > > > Did you define (implement) the function somewhere?
> > > > gcc is a very good compiler, I'm sure it follows all the
> standards.
> > > >
> > > > ________________________________________
> > > > From: David Cespedes
> > > > Sent: Thursday, October 27, 2005 11:02 AM
> > > > To: Paul
> > > > Subject: Linux C++ implementation
> > > > Hi Paul!
> > > >
> > > > Once again I see myself baffled by a C++ questions and you are my
> > last
> > > source for an educated answer. Anyhow, I have just started
> developing
> > > under the Linux platform using the gcc 2.96; do not ask why that
> > version
> > > I do not control it.
> > > >
> > > > So I am working along and, by now, C++ is supposed to be C++ on
> any
> > > platform, until I declare a static method function and member in a
> > > class; see sample code. When I do this, if I try to use the global
> > scope
> > > CSample::Test(...), the linker tells me that the function is an
> > > undefined reference???
> > > >
> > > > What happen here are? Did then gcc folks confuse the "C" vs. "C++"
> > > interpretation of a static scope? I need help...
> > > >
> > > > class CSample
> > > > {
> > > > public:
> > > > CSample();
> > > > ~CSample();
> > > > static void test(unsigned char foo);
> > > >
> > > > protected:
> > > > static bool m_bState;
> > > > };
> > > >
> > > > Best regards,
> > > >
> > > > ________________________________________
> > > > David A. Cespedes
> > > > Chief Software Engineer - Manager
> > > > I/O Marine Imaging Systems Division
> > > > Office: 281.879.2171
> > > >
> > > >
> > >
> >
>

RE: C++ static member function reported as undefined references by linker?

[David Cespedes]

If inside a namespace, yes. But not inside a class, unless the class is
inside a namespace.

See the ARM (Annotated Reference Manual), Sec 9.4:
"Static members of a global class have external linkage."

-----Original Message-----
From: corey taylor [mailto:corey.taylor@gmail.com] 
Sent: Thursday, October 27, 2005 1:07 PM
To: David Cespedes; gcc-help@gnu.org
Subject: Re: C++ static member function reported as undefined references
by linker?

This is according to the C++ specification.  Check out section 3.5
(Program and Linkage) of the 14882:2003 specification.

Corey

On 10/27/05, David Cespedes <David.Cespedes@i-o.com> wrote:
> You are right, it worked. Is this an artifact of the gcc? I am nit
sure
> this is 100% compliant with the C++ spec. I see this as a work around,
> thank you for all the help
>
> Regards
> Daveed
>
> -----Original Message-----
> From: corey taylor [mailto:corey.taylor@gmail.com]
> Sent: Thursday, October 27, 2005 12:30 PM
> To: David Cespedes
> Subject: Re: C++ static member function reported as undefined
references
> by linker?
>
> You will automatically get external linkage when declared inside of a
> named namespace.
>
> corey
>
> On 10/27/05, David Cespedes <David.Cespedes@i-o.com> wrote:
> > Well show does a class have external linkage? I though this was the
> > default? Please show me an example.
> >
> > Regards,
> > Daveed
> >
> > -----Original Message-----
> > From: corey taylor [mailto:corey.taylor@gmail.com]
> > Sent: Thursday, October 27, 2005 11:40 AM
> > To: David Cespedes
> > Cc: gcc-help@gcc.gnu.org
> > Subject: Re: C++ static member function reported as undefined
> references
> > by linker?
> >
> > David,
> >
> >   As far as I know, they only have external linkage if the class has
> > external linkage.
> >
> > Corey
> >
> > On 10/27/05, David Cespedes <David.Cespedes@i-o.com> wrote:
> > > Can you help with this issue, in regards to C++ static member
> > functions and why they are reported as undefined references by the
> > linker?
> > >
> > > Please see attached email trail!
> > >
> > > Best Regards
> > > Daveed
> > > ________________________________________
> > > From: Paul
> > > Sent: Thursday, October 27, 2005 10:40 AM
> > > To: David Cespedes
> > > Subject: RE: Linux C++ implementation
> > >
> > > I don't know enough about Linux/gcc to help.
> > > static members are supposed to have external linkage--ARM Sec 9.4
> > >
> > > ________________________________________
> > > From: David Cespedes
> > > Sent: Thursday, October 27, 2005 11:46 AM
> > > To: Paul
> > > Subject: RE: Linux C++ implementation
> > > Yes, I did! I have a Sample.h for the definition and Sample.cpp
> where
> > there is a void CSample::test(unsigned char foo) { ... }
> implementation.
> > >
> > > The only work-around I found is to implement the method function
in
> > the definition .H file (inline it) and I must declare the static
> member
> > as an "extern bool CSample::m_bState" in order to see it, from an
> > outside scope.
> > >
> > > ________________________________________
> > > From: Paul
> > > Sent: Thursday, October 27, 2005 10:40 AM
> > > To: David Cespedes
> > > Subject: RE: Linux C++ implementation
> > >
> > > Did you define (implement) the function somewhere?
> > > gcc is a very good compiler, I'm sure it follows all the
standards.
> > >
> > > ________________________________________
> > > From: David Cespedes
> > > Sent: Thursday, October 27, 2005 11:02 AM
> > > To: Paul
> > > Subject: Linux C++ implementation
> > > Hi Paul!
> > >
> > > Once again I see myself baffled by a C++ questions and you are my
> last
> > source for an educated answer. Anyhow, I have just started
developing
> > under the Linux platform using the gcc 2.96; do not ask why that
> version
> > I do not control it.
> > >
> > > So I am working along and, by now, C++ is supposed to be C++ on
any
> > platform, until I declare a static method function and member in a
> > class; see sample code. When I do this, if I try to use the global
> scope
> > CSample::Test(...), the linker tells me that the function is an
> > undefined reference???
> > >
> > > What happen here are? Did then gcc folks confuse the "C" vs. "C++"
> > interpretation of a static scope? I need help...
> > >
> > > class CSample
> > > {
> > > public:
> > > CSample();
> > > ~CSample();
> > > static void test(unsigned char foo);
> > >
> > > protected:
> > > static bool m_bState;
> > > };
> > >
> > > Best regards,
> > >
> > > ________________________________________
> > > David A. Cespedes
> > > Chief Software Engineer - Manager
> > > I/O Marine Imaging Systems Division
> > > Office: 281.879.2171
> > >
> > >
> >
>

Re: C++ static member function reported as undefined references by linker?

[corey taylor]

This is according to the C++ specification.  Check out section 3.5
(Program and Linkage) of the 14882:2003 specification.

Corey

On 10/27/05, David Cespedes <David.Cespedes@i-o.com> wrote:
> You are right, it worked. Is this an artifact of the gcc? I am nit sure
> this is 100% compliant with the C++ spec. I see this as a work around,
> thank you for all the help
>
> Regards
> Daveed
>
> -----Original Message-----
> From: corey taylor [mailto:corey.taylor@gmail.com]
> Sent: Thursday, October 27, 2005 12:30 PM
> To: David Cespedes
> Subject: Re: C++ static member function reported as undefined references
> by linker?
>
> You will automatically get external linkage when declared inside of a
> named namespace.
>
> corey
>
> On 10/27/05, David Cespedes <David.Cespedes@i-o.com> wrote:
> > Well show does a class have external linkage? I though this was the
> > default? Please show me an example.
> >
> > Regards,
> > Daveed
> >
> > -----Original Message-----
> > From: corey taylor [mailto:corey.taylor@gmail.com]
> > Sent: Thursday, October 27, 2005 11:40 AM
> > To: David Cespedes
> > Cc: gcc-help@gcc.gnu.org
> > Subject: Re: C++ static member function reported as undefined
> references
> > by linker?
> >
> > David,
> >
> >   As far as I know, they only have external linkage if the class has
> > external linkage.
> >
> > Corey
> >
> > On 10/27/05, David Cespedes <David.Cespedes@i-o.com> wrote:
> > > Can you help with this issue, in regards to C++ static member
> > functions and why they are reported as undefined references by the
> > linker?
> > >
> > > Please see attached email trail!
> > >
> > > Best Regards
> > > Daveed
> > > ________________________________________
> > > From: Paul
> > > Sent: Thursday, October 27, 2005 10:40 AM
> > > To: David Cespedes
> > > Subject: RE: Linux C++ implementation
> > >
> > > I don't know enough about Linux/gcc to help.
> > > static members are supposed to have external linkage--ARM Sec 9.4
> > >
> > > ________________________________________
> > > From: David Cespedes
> > > Sent: Thursday, October 27, 2005 11:46 AM
> > > To: Paul
> > > Subject: RE: Linux C++ implementation
> > > Yes, I did! I have a Sample.h for the definition and Sample.cpp
> where
> > there is a void CSample::test(unsigned char foo) { ... }
> implementation.
> > >
> > > The only work-around I found is to implement the method function in
> > the definition .H file (inline it) and I must declare the static
> member
> > as an "extern bool CSample::m_bState" in order to see it, from an
> > outside scope.
> > >
> > > ________________________________________
> > > From: Paul
> > > Sent: Thursday, October 27, 2005 10:40 AM
> > > To: David Cespedes
> > > Subject: RE: Linux C++ implementation
> > >
> > > Did you define (implement) the function somewhere?
> > > gcc is a very good compiler, I'm sure it follows all the standards.
> > >
> > > ________________________________________
> > > From: David Cespedes
> > > Sent: Thursday, October 27, 2005 11:02 AM
> > > To: Paul
> > > Subject: Linux C++ implementation
> > > Hi Paul!
> > >
> > > Once again I see myself baffled by a C++ questions and you are my
> last
> > source for an educated answer. Anyhow, I have just started developing
> > under the Linux platform using the gcc 2.96; do not ask why that
> version
> > I do not control it.
> > >
> > > So I am working along and, by now, C++ is supposed to be C++ on any
> > platform, until I declare a static method function and member in a
> > class; see sample code. When I do this, if I try to use the global
> scope
> > CSample::Test(...), the linker tells me that the function is an
> > undefined reference???
> > >
> > > What happen here are? Did then gcc folks confuse the "C" vs. "C++"
> > interpretation of a static scope? I need help...
> > >
> > > class CSample
> > > {
> > > public:
> > > CSample();
> > > ~CSample();
> > > static void test(unsigned char foo);
> > >
> > > protected:
> > > static bool m_bState;
> > > };
> > >
> > > Best regards,
> > >
> > > ________________________________________
> > > David A. Cespedes
> > > Chief Software Engineer - Manager
> > > I/O Marine Imaging Systems Division
> > > Office: 281.879.2171
> > >
> > >
> >
>