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Message-ID:	<002301c31c38$7d9c56d0$2180a8c0@toshiba>
From:	"Campbell" <cf AT cannex DOT com DOT au>
To:	<cygwin AT cygwin DOT com>
References:	<Pine DOT GSO DOT 4 DOT 44 DOT 0305162222110 DOT 8930-100000 AT slinky DOT cs DOT nyu DOT edu>
Subject:	Re: Porting - link error
Date:	Sat, 17 May 2003 15:52:09 +1000
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I wrote:
>
> > Trying to port heyu2. (Command line interface for x10 home automation.
See
> > http://heyu.tanj.com/heyu2/. Basically, it just sends commands to a
serial
> > port, and spawns a daemon to listen for responses.)
> >
> > Achieved clean compile after adding a few #include<>'s and changing
timezone
> > to _timezone.
> >
> > When attempting to link:
> >
> > gcc  -o heyu2 date.o erase.o info.o message.o relay.o monitor.o reset.o
setclock.o stop.o tty.o turn.o x10.o xread.o xwrite.o status.o cm11a.o
eeprom.o preset.o process.o sun.o -lm -lc
> > fu000001.o(.idata$3+0xc): undefined reference to
`__cygnus_netrel_build_cygwin_1_3_22_1_i686_pc_cygwin_winsup_cygwin_libc_a_i
name'
> > fu000002.o(.idata$3+0xc): undefined reference to
`__cygnus_netrel_build_cygwin_1_3_22_1_i686_pc_cygwin_winsup_cygwin_libc_a_i
name'
> > fu000005.o(.idata$3+0xc): undefined reference to
`__cygnus_netrel_build_cygwin_1_3_22_1_i686_pc_cygwin_winsup_cygwin_libc_a_i
name'
> > fu000006.o(.idata$3+0xc): undefined reference to
`__cygnus_netrel_build_cygwin_1_3_22_1_i686_pc_cygwin_winsup_cygwin_libc_a_i
name'
> > nmth000000.o(.idata$4+0x0): undefined reference to `__nm___tzname'
> > Info: resolving __tzname by linking to __imp___tzname (auto-import)
> > collect2: ld returned 1 exit status
> > make: *** [heyu2] Error 1
> >
> > nm lists a symbol
> >
___cygnus_netrel_build_cygwin_1_3_22_1_i686_pc_cygwin_winsup_cygwin_libc_a_i
name
> > in /lib/libc.a with three leading underscores.
> > I looked in man ld, but couldn't find anything to help.
> >

Igor wrote:

> The fact that you had to change timezone to _timezone should have been
> your first clue.  There is something wrong with the name mangling (perhaps
> a wrong calling convention declared?) for that particular project.  You
> might want to look into gcc's "-fleading-underscore" option ("info gcc").
> Igor

Thank you, Igor. Good suggestion.

Tried adding -fleading-underscore to the compile flags. No change.

Tried adding -fno-leading-underscore to the compile flags. Squillions of
link errors. Not really surprising.

My understanding is that under cygwin, timezone is a function, not a global
variable. _timezone is the equivalent global variable. See
https://www.zend.com/lists/php-dev/200203/msg00119.html and
http://www.cygwin.com/ml/cygwin/2001-12/msg01324.html.

I can't find anything in the makefile that would upset name mangling.
CC = gcc
CFLAGS = -g -O $(DFLAGS) -Wall
DFLAGS = -DSYSV -DHAS_ITIMER -DHASSELECT
LIBS = -lm -lc

It's really strange that there is a problem with only one symbol, and that
one symbol is defined in libc.a.

Campbell.


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