Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!uxc!deimos.cis.ksu.edu!rutgers!att!pegasus!hansen
From: hansen@pegasus.ATT.COM (Tony L. Hansen)
Newsgroups: comp.lang.c++
Subject: Re: C --> C++
Summary: cfront 2.0 does not mangle extern "C" names
Keywords: extern, linkage specifications
Message-ID: <2857@pegasus.ATT.COM>
Date: 4 May 89 01:28:53 GMT
References: <6590096@hplsla.HP.COM> <11437@ulysses.homer.nj.att.com> <578@hrc63.co.uk>
Reply-To: hansen@pegasus.ATT.COM (Tony L. Hansen)
Organization: AT&T Bell Laboratories, Lincroft, NJ, USA
Lines: 47

<> >Can you
<> >do a extern "C" like construct that goes the other
<> >way?
<>
<> You should have added "in a portable way"...
<> Since C++ doesn't have a standard naming convention for generating
<> unique names for the loader, each compiler does its own name mangling.
<
< Yes, but I should be able to tell the compiler "dont mangle this function
< name".  A #pragma or something.  It would still be callable from C++ (via
< the `extern "C"' mechanism).
<
< Speaking as someone who has tried to do this, I think it is a major gap in
< the langauge.

The extern "language" linkage specification works both ways. Not only can
one specify that a function has been written in C, one can also specify that
a C++ function is to be linked just as a C function would be linked. For
example,

	#include <stdio.h>

	extern "C" void foo() { printf("foo\n"); }

	void bar() { printf("bar\n"); }

	main()
	{
		foo();
		bar();
	}

the function "bar" will be known externally as the mangled name (such as
"bar__Fv" or "bar__Nv"), but the function "foo" will be known externally as
the unmangled name "foo". Both cfront 2.0 and Zortech's next C++ compiler
work this way.

By the way, the next version of Zortech's C++ compiler will also support the

	extern "Pascal"

linkage specification, in addition to the extern "C" and "C++" linkage
specifications.

					Tony Hansen
				att!pegasus!hansen, attmail!tony
				    hansen@pegasus.att.com