Date: Fri, 17 Mar 1995 12:30:59 -0800 From: "Justin T. Gibbs" <gibbs@estienne.CS.Berkeley.EDU> To: nate@FreeBSD.org Cc: current@FreeBSD.org Subject: Patch for gcc Message-ID: <199503172031.MAA16609@estienne.cs.berkeley.edu>
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On of the professors I work for pointed this out to me:
Begin Forwarded Message
-----------------------
Gcc v2.6.3 currently has a problem with templates. Specifically, with
default switches, template functions get EXTERNAL linkage in each file
in which they occur, causing multiple definition errors during
linking. The enclosed patch (from gnu.g++.bug) appears to solve the
problem (I enclose the accompanying message as well). It would be
nice to install this in /usr/local/bin.
Paul
- --------------------------------------------------
Article: 14433 of gnu.g++.bug
From: rjl@iassf.easams.COM.AU (Rohan LENARD)
Newsgroups: gnu.g++.bug
Subject: Re: Multiple Method Definitions in Templates
Date: 8 Mar 1995 17:23:44 -0500
Organization: GNUs Not Usenet
Lines: 136
Sender: daemon@cis.ohio-state.edu
Approved: bug-g++@prep.ai.mit.edu
Distribution: gnu
Message-ID: <0jLUto3_3gX_0Ak1g0@iassf.easams.com.au>
References: <10330.794622376@N2.SP.CS.CMU.EDU>
Hi there,
Thanks for the bug report.
I forgot to supply the patch for this problem in my previous mail. Here it is -
Regards,
Rohan
- ------------------------------------------------------------------------
(Thanks to Jason Merrill at cygnus support).
This patch fixes the multiply defined template functions bug
which was introduced in 2.6.1.
Jason
*** ../../gcc-2.6.3/cp/pt.c Mon Nov 14 23:34:29 1994
- --- pt.c Mon Dec 12 21:10:06 1994
***************
*** 2302,2307 ****
- --- 2302,2311 ----
else if (! flag_implicit_templates)
DECIDE (0);
+ if (i->interface == 1)
+ /* OK, it was an implicit instantiation. */
+ TREE_PUBLIC (t) = 0;
+
/* If it's a method, let the class type decide it.
@@ What if the method template is in a separate file?
Maybe both file contexts should be taken into account?
- ------------------------------------------------------------------------
Excerpts from BugReport.Gnu: 7-Mar-95 Multiple Method Definitions..
Peter_Stephan@n2.sp.cs.c (2274)
> I encountered a situation which I believe is a bug. It occurs
> in version 2.6.3 of g++ on both DEC Alphas running OSF1 v2.0 and
> SUN4s running SunOS v4.1.3.
> The situation occurs when using a C++ template in two or more
> modules which are ultimately linked together and is similar to another
> bug report that I have just submitted. As seen in the brief examples
> below, I have defined a templated class, dv, with a method print. I have
> also defined a version of the print method specifically for instantiations
> of this template with <char>. The linker identifies the print method as
> being multiply defined. If there is only one module to this system, it
> seems to work fine. When the example code given is compiled and linked,
> the following output results:
> pheasant <278> g++ -fexternal-templates -c prog1.C -o prog1.o
> pheasant <279> g++ -fexternal-templates -c prog2.C -o prog2.o
> pheasant <280> g++ -fexternal-templates prog1.o prog2.o -o prog
> ld: prog2.o: _print__t2dv1Zc: multiply defined
> collect2: ld returned 2 exit status
> This problem was not exhibited when using g++ version 2.5.8 on the
> same platforms without the #pragma and -fexternal-templates stuff.
> Any information would be appreciated.
> Thank you,
> Peter
> ---
> Peter Stephan CMU School of Computer Science
> pstephan@cs.cmu.edu Wean Hall Room 7106
> Research Programmer (412) 268-7663
> /***** prog.h ******/
> #pragma interface
> #include <iostream.h>
> template <class TYPE> class dv {
> public:
> dv(TYPE d) {
> data = d;
> }
> ~dv() {}
> void print();
> private:
> TYPE data;
> };
> template <class TYPE> void dv<TYPE>::print() {
> cout << "Data = " << "." << data << "\n";
> return;
> }
> void dv<char>::print() {
> cout << "Char = " << data << ".\n";
> return;
> }
> /***** end of prog.h ******/
> /***** prog1.C *****/
> #pragma implementation "prog.h"
> #include "prog.h"
> extern void another_routine();
> main() {
> dv<int> vi(8);
> dv<char> vc('z');
> vi.print();
> vc.print();
> another_routine();
> cout << "Normal program termination." << endl;
> }
> /***** end of prog1.C *****/
> /***** prog2.C *****/
> #include "prog.h"
> void another_routine() {
> dv<int> vi(1);
> vi.print();
> cout << "Finished in another_routine." << endl;
> }
> /***** end of prog2.C *****/
------- End of Forwarded Message
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