Re: std::atexit and c++ linkage handler
Jiang wrote:
Can we register c++ linkage functions with std::atexit ?
You should be able to.
For following example,
[example]
$ cat atexit.cpp
#include <cstdlib>
#include <iostream>
void foo(){std::cout<<"foo";}
int main()
{
std::atexit(foo);
}
[end example]
The Comeau compiler complains that:
$ como --A atexit.cpp
Comeau C/C++ 4.3.3 (Jan 13 2004 11:29:09) for MS_WINDOWS_x86
Copyright 1988-2003 Comeau Computing. All rights reserved.
MODE:strict errors C++
"atexit.cpp", line 9: error: argument of type "void (*)()" is
incompatible
with parameter of type "void (*)() C"
std::atexit(foo);
1 error detected in the compilation of "atexit.cpp".
And gcc compiles it even "-std=c++98 -pedantic" used.
There's a known error in g++ in this respect. It doesn't handle
language bindings correctly.
I checked 3.6.3/p3 and 18.3, but it seems the standard says
nothing about the handler function's linkage. Which behavior
is correct?
?18.3/3 requires an overload of atexit: an extern "C" version
which takes an extern "C" function, and an extern "C++" version
which takes an extern "C++" function. In practice, however, not
all compilers fully make the distinction, and libraries
developped with such a compiler in mind may not reflect this.
Thus, under Solaris, the bundled system headers do not contain
an overload, even though versions of Sun CC have warned about an
anachronism for some time now.
Compilers like g++ (and Como?) normally use the bundled system
headers, at least under Unix. From you're error message, I
would guess that Como is handling this correctly, but that your
library headers are not up to date. And that g++ doesn't
complain because of its own error; it's a case of the two errors
cancelling out. (Note that this error in g++ means that it
won't necessarily compile a conformant version of cstdlib, e.g.
if the two functions are inline. And that it may call the wrong
one if they aren't.)
I'll admit that I can't really understand this. Language
linkage must be part of the type for it to make sense, and even
the very first C++ I used (Zortech 1.something) got it right.
Never the less, neither g++ nor VC++ get it right, even in their
latest versions, and Sun CC apparently didn't get it right in
earlier versions, whence a warning and not an error. (I find it
particularly worrisome that VC++ gets it wrong, since the only
intelligent calling conventions on a PC are different in C and
C++. So calling a C++ function with a pointer to a C function
will wreck havoc. Again, Zortech got this right well over 15
years ago.)
--
James Kanze GABI Software
Conseils en informatique orient?e objet/
Beratung in objektorientierter Datenverarbeitung
9 place S?mard, 78210 St.-Cyr-l'?cole, France, +33 (0)1 30 23 00 34
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
[ comp.lang.c++.moderated. First time posters: Do this! ]