emacs-23.1.96: problem, and workaround, on GNU/Linux Gentoo Alpha

emacs-23.1.96: problem, and workaround, on GNU/Linux Gentoo Alpha

[Nelson H. F. Beebe]

A build of emacs-23.1.96 on

	DEC Alphastation 200 4/100 (1 CPU, 100 MHz Alpha 21064 EV4, 128MB RAM)
	GNU/Linux 2.6.31-gentoo-r7

initially failed like this in the final link of emacs:

	/usr/local/lib/libncurses.a(lib_termcap.o):(.sbss+0x0): multiple definition of `UP'
	terminfo.o:(.sbss+0x0): first defined here
	/usr/local/lib/libncurses.a(lib_termcap.o):(.sbss+0x8): multiple definition of `BC'
	terminfo.o:(.sbss+0x8): first defined here
	/usr/local/lib/libncurses.a(lib_tputs.o):(.sbss+0x0): multiple definition of `PC'
	terminfo.o:(.sbss+0x10): first defined here
	collect2: ld returned 1 exit status

Switching to /usr/lib/libcurses.{a,so} or /usr/lib/libncurses.{a,so}
did not help: the same multiple definitions remain.

I therefore made a small code modification

	% diff terminfo.c~ terminfo.c
	28c28
	< char *UP, *BC, PC;
	---
	> extern char *UP, *BC, PC;

and restarted the build.  That simple change produced a completely
successful build and installation.

I have seen the same problem with those three symbols in other
packages as well; it is not clear to me why on Alpha GNU/Linux one
gets the multiple-definition error, but not on other CPU
architectures.  We run the same Gentoo versions on PowerPC and SPARC
systems, and no such problems are seen there.

With nm, I see these differences:

	Alpha:
		% nm /usr/lib/libcurses.a | egrep 'UP|BC|PC'
				 U PC
		0000000000000008 S BC
				 U PC
		0000000000000000 S UP
		0000000000000000 S PC

	PowerPC:
		% nm /usr/lib/libcurses.a | egrep 'UP|BC|PC'
				 U PC
		0000000000000008 B BC
				 U PC
		0000000000000000 B UP
		0000000000000008 B PC

	SPARC:
		% nm /usr/lib/libcurses.a | egrep 'UP|BC|PC'
			 U PC
		00000004 B BC
			 U PC
		00000000 B UP
		00000000 B PC

Notice that their symbol type code is S on Alpha, and B on the other
two CPUs.  From "man nm", the type codes are documented like this:

	"B"
	"b" The symbol is in the uninitialized data section (known as BSS).

	"S"
	"s" The symbol is in an uninitialized data section for small
	    objects.

Running "strings /usr/bin/ld | grep binutils" shows these package
origins:

	Alpha	binutils-2.18-r3
	PowerPC	binutils-2.19
	SPARC	binutils-2.18

Anyone care to speculate that the multiple-definition error might be a
GNU ld bug in the binutils distribution?

-------------------------------------------------------------------------------
- Nelson H. F. Beebe                    Tel: +1 801 581 5254                  -
- University of Utah                    FAX: +1 801 581 4148                  -
- Department of Mathematics, 110 LCB    Internet e-mail: beebe@math.utah.edu  -
- 155 S 1400 E RM 233                       beebe@acm.org  beebe@computer.org -
- Salt Lake City, UT 84112-0090, USA    URL: http://www.math.utah.edu/~beebe/ -
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