[Bug target/39578] Linkage broken for dllimport vtables

[dave dot korn dot cygwin at gmail dot com]

------- Comment #1 from dave dot korn dot cygwin at gmail dot com  2009-03-29 17:47 -------
For Cygwin, we just recently made --enable-auto-import the default in CVS
binutils.  Now that we're moving to shared library runtimes throughout it made
sense.

However, I think this is a real bug, as it doesn't happen on 4.3.2; we get a
direct undefined reference to the import symbol in the object file:

$ g++ -g -o vttest.exe vttest.cpp libvttest.dll.a --save-temps

admin@ubik /tmp/vttest
$ nm vttest.o
00000000 b .bss
00000000 d .data
00000000 N .debug_abbrev
00000000 N .debug_aranges
00000000 N .debug_frame
00000000 N .debug_info
00000000 N .debug_line
00000000 N .debug_loc
00000000 N .debug_pubnames
00000000 N .debug_ranges
00000000 N .debug_str
00000000 d .eh_frame
00000000 t .text
00000000 t .text$_ZN10TestObjectC1Ev
00000000 T __ZN10TestObjectC1Ev
         U ___gxx_personality_v0
         U ___main
         U __imp___ZN10TestObject8VirtFuncEv
         U __imp___ZTV10TestObject
00000000 T _main

admin@ubik /tmp/vttest
$ 

My earlier build of 4.3.3 with the patch for PR36654 reverted does the same
thing.  However, as soon as I reapplied the patch and rebuilt cc1plus, I got
this output:

/tmp/vttest $ nm vttest.o    libvtt
00000000 b .bss
00000000 d .data
00000000 N .debug_abbrev
00000000 N .debug_aranges
00000000 N .debug_frame
00000000 N .debug_info
00000000 N .debug_line
00000000 N .debug_loc
00000000 N .debug_pubnames
00000000 N .debug_ranges
00000000 N .debug_str
00000000 d .eh_frame
00000000 t .text
00000000 t .text$_ZN10TestObjectC1Ev
00000000 T __ZN10TestObjectC1Ev
         U __ZTV10TestObject
         U ___gxx_personality_v0
         U ___main
         U __imp___ZN10TestObject8VirtFuncEv
00000000 T _main
/tmp/vttest $

So I think that confirms it.


-- 

dave dot korn dot cygwin at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dave dot korn dot cygwin at
                   |                            |gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39578