Subject: Re: C++, libtool and a.out
To: Nick Hudson <>
From: Todd Vierling <>
List: tech-pkg
Date: 06/21/2000 23:11:11
On Wed, 21 Jun 2000, Nick Hudson wrote:

: OK so pkglibtool supported C++ constructors and destructors on a.out
: systems by introducing the cplusplus flag which would link in
: /usr/lib/c++rt0.o if specified. I would to apply the attached patch
: so that libtool 1.3.5 will also support C++ and a.out.

Be careful hardcoding /usr/lib here.  Think about cross compilation.

The best solution would be to check whether or not "cc -shared" works
properly (a fix went in between 1.3 and 1.4), and use that.  It will link in
c++rt0.o automatically, from the "normal library path".  If we want to add
this for 1.3-and-before systems (that do not have a specially updated
compiler), it can then be done manually, provided "cc -shared" does not work

How to check?  Use the following:

    if $CC -dumpspecs | grep 'c++rt0' >/dev/null; then
        # use "cc -shared" for shared objects
        # use "ld -Bshareable" and manually tack on c++rt0

Note that this check is only necessary for a.out.  For ELF, "cc -shared" is
already usable.  Also note that we cannot use "grep -q" in the cross
compilation case; hence "grep >/dev/null".

-- Todd Vierling (