S: Create a typedef with either C or C++ linkage and use it as the argument type.

Q: How do I link C++ with another language?

A: See Using Compaq C++ with Other Languages. One caveat for linking with Fortran is that in many cases Fortran add a trailing underscore to its external name. The externC declaration must include this underscore when you define an external Fortran name. See -assume nounderscore in the Fortran f77 and f90 reference pages.

Q: Why does the compiler generate undefined symbol WHAT__K9BAD_ALLOCXV?

A: The library object file bv_inst.o, which was created incorrectly, contains an undefined symbol bad_alloc::what().

If you #include <vector>, some inline functions in the bitvector class (at the bottom of the vector header file) cause the linker to require references from bv_inst.o. The unresolved error occurs when the linker includes that object file. Though disconcerting, the linker error is harmless.

S: This problem has been fixed in Version 6.n of the Standard Library.

W: In most cases, you can ignore the linker message. It is a problem only if a shareable image is being created (because any application linking against it also receives the warning.

Q: Why must classes reside in headers for automatic template instantiation?
Q: Why does the compiler generate undefined template symbols?

A: This was a limitation in the Version 5.n compilers that has been fixed in the Version 6.n compilers. For more information about Version 5 template limitations, see the discussion of templates in your Version 5.n Using DEC C++ guide.

S: Upgrade to Version 6.0 or higher.

Q: Why does the compiler generate duplicate symbol errors when I use automatic instantiation?

A: This was a limitation in the Version 5.n compilers that has been fixed in the Version 6.n compilers. For more information about Version 5 template limitations, see the discussion of templates in your Version 5.n Using DEC C++ guide.

Note also that you cannot do automatic template instantiation if you defined templates and non-templates in the same module. This restriction applies because each time the compiler needs the template implementation, it includes the module that defines it. If that module contains non-template elements, these also are defined, and duplicate symbols can be generated.

Consider the following example:

mynode> cxx -o tt m.cxx m2.cxx t.cxx
m.cxx:
m2.cxx:
t.cxx:
ld (prelink):
m2.o compressed: worker_function(void): multiply defined
t.o compressed: worker_function(void): multiply defined
ld (prelink):
m2.o compressed: worker_function(void): multiply defined
t.o compressed: worker_function(void): multiply defined
ld:
m2.o compressed: worker_function(void): multiply defined
t.o compressed: worker_function(void): multiply defined

mynode> nm m.o | grep worker
worker_function(void)            | 0000000000000080 | T | 0000000000000008
mynode> nm m2.o | grep worker
worker_function(void)            | 0000000000000064 | T | 0000000000000008
mynode> nm t.o | grep worker
worker_function(void)            | 0000000000000000 | T | 0000000000000008

mynode> cat t.h
#ifndef T_H
#define T_H
template  void f(const T);
#endif

mynode> cat t.cxx
#include "t.h"

void worker_function() { }

template  void f(const T) { worker_function(); }

mynode> cat m.cxx
#include "t.h"

extern void m2();

void main()
{
  f(1);
  m2();
}

mynode> cat m2.cxx
#include "t.h"

void m2()
{
  f("hello");
}

For information about where to place function definitions depending on whether they are templatized, see How to Organize Your C++ Code in Using Compaq C++ for OpenVMS Alpha

Q: Why am I having trouble with the Standard Library?
Q: Why does the Standard Library produce the warning message 'qualifier is meaningless on cast type'?

A: When using Standard Library container classes with Compaq C++ Version 6.n, you might receive a message like the following:

cxx: Warning: /usr/include/cxx/utility, line 131: type qualifier is meaningless on cast type detected during: instantiation of "std::pair<const int, char>::pair() ... : first(T1()), second(T2()) --------^

The preceding was generated from the following:

typedef multimap<int, char, less<int> > mmap; typedef pair<int, char> pair_type; pair_type p1 (3, 'c'); pair_type p2 (4, 'd'); ... pair_type array [] = {p1,p2,p3,p4,p5,p6}; mmap m (array, array + 6);

The reason for this warning is that internally the container classes may make calls to Standard Library utilities like pair() which make use of functional-notation casts. For example pair() makes use of first(T1()). In this example T1() is a functional-notation cast to type T1. The type in a functional-notation cast has to be a single type identifier. Internally the library may add the const qualifier to a template type to ensure "constness". In the above example this has happened leading to an instantiation of first (const int()), which generates a warning.

S: This problem is corrected in Version 6.1 for Compaq Tru64 UNIX.

W: Disable the message on the command line.

Q: Because the Standard Library does not ship with the operating system, how can my customer obtain the library so that my application will link cleanly on his system?

A: You can redistribute the library under conditions specified in the C++ Software Product Description. For detailed information about how to do so, see Deploying Your Application in Using Compaq C++ for Tru64 UNIX.

Q: Why does the compiler generate undefined nullref and nullref_defined messages?

A: The headers and the library shipped with the Version 6.0 compiler were not consistent.

S: Upgrade to Version 6.1 or higher.

Q: Why does the compiler receive an internal error, GEM ASSERTION?
Q: Why does the compiler crash or produce a core dump?

A: This is a Version 6.0 compiler problem. Users of the Version 6.0 compiler can encounter a GEM ASSERTION on code containing the expression b ? true : false.

You can search for occurrences in your code by enterting:

grep "?" *.cxx *.h | grep true

and

grep "?" *.cxx *.h | grep false

S: Upgrade to the latest version. If the problem persists, please report it to customer support. Be prepared to supply a preprocessed file along with the compiler flags that you are using.

Q: Why does the compiler warn that /usr/include/pdsc.h has nested comments?