no support for undefined weak 16-bit coff symbols

[Jay Foad]

I configured binutils 2.18 for z80-unknown-coff and tried this:

$ cat a.s
.weak foo
call foo
$ objdir-z80/gas/as-new -o a.o a.s
$ objdir-z80/binutils/objdump -tdr a.o

a.o:     file format coff-z80

SYMBOL TABLE:
[  0](sec -2)(fl 0x00)(ty   0)(scl 103) (nx 1) 0x00000000 fake
File
[  2](sec  1)(fl 0x00)(ty   0)(scl   3) (nx 1) 0x00000000 .text
AUX scnlen 0x3 nreloc 1 nlnno 0
[  4](sec  2)(fl 0x00)(ty   0)(scl   3) (nx 1) 0x00000000 .data
AUX scnlen 0x0 nreloc 0 nlnno 0
[  6](sec  3)(fl 0x00)(ty   0)(scl   3) (nx 1) 0x00000000 .bss
AUX scnlen 0x0 nreloc 0 nlnno 0
[  8](sec  0)(fl 0x00)(ty   0)(scl 127) (nx 0) 0x00000000 foo


Disassembly of section .text:

00000000 <.text>:
   0:   cd 00 00        call 0x0000
                        1: r_imm16      foo
$ objdir-z80/ld/ld-new -o a a.o
a.o:fake:(.text+0x1): undefined reference to `foo'

It looks like bfd_coff_reloc16_get_value() doesn't know about
undefined weak symbols. This patch fixes the problem for me:

--- ../binutils-2.18/bfd/reloc16.c      2007-08-06 20:59:40.000000000 +0100
+++ bfd/reloc16.c       2008-04-24 11:10:17.000000000 +0100
@@ -76,6 +76,10 @@
       else if (h != (struct bfd_link_hash_entry *) NULL
               && h->type == bfd_link_hash_common)
        value = h->u.c.size;
+      else if (h != (struct bfd_link_hash_entry *) NULL
+              && h->type == bfd_link_hash_undefweak)
+       /* This is a GNU extension.  */
+       value = 0;
       else
        {
          if (!((*link_info->callbacks->undefined_symbol)

Thanks,
Jay.