On Wed, 29 Dec 2021, Gisle Vanem wrote:
Martin Storsjö wrote:
In the meantime, when you create your regular import library with an
option like -Wl,--out-implib,libfoo.dll.a, add the
option -Wl,--output-def,foo.def. After that, run "dlltool -d foo.def -l
libfoo.dll.a". This recreates the import library
in a form that works better with MS link.exe.
Thanks a lot.
Maybe I have to add '--kill-at' too?
Yes, possibly - if you're exporting stdcall/fastcall functions.
These are my steps:
gcc -o ../bin/liquid32.dll -shared -m32 \
-static-libgcc \
-Wl,--out-implib,../liquid32.dll.a \
-Wl,--output-def,MinGW_obj32/liquid32.def \
MinGW_obj32/libliquid.o
...
And:
dlltool --input-def MinGW_obj32/liquid32.def --dllname liquid32.dll \
--output-lib ../liquid32_imp.lib --kill-at --machine i386
But now I get tons of warnings from 'link.exe'.
Like:
Loaded liquid32_imp.lib(dolms02750.o)
module 'liquid32_imp.lib(dolms02750.o)' unsafe for SAFESEH image.
and lots of these:
liquid32_imp.lib(dolms00002.o) :
error LNK2001: unresolved external symbol __head____liquid32_imp_lib
What's these '__head____*' symbols?
For reference my dlltool has version
(GNU Binutils) 2.36.1
Hmm, that's quite strange - is there any difference if you'd name the file
liquid32.dll.a instead of liquid32_imp.lib? Because technically, the new
file you generated and the one from --out-implib from ld should be
virtually identical, except for the minor detail that makes it break when
linking two of them with MS link.exe.
The __head__* symbols are internal details in the import libs. The import
libs consist of a bunch of object files. When you have a reference against
e.g. myLibFunc, there's one object in the import lib that provides it.
That object file then has a reference to symbols defined in a separate
header object file in the import library.
Make sure you only specify this new import library to link.exe, not the
old version of it.
If you inspect the new import lib with nm, I would expect it to have one
object file providing the symbol that you mentioned to be missing.
(When inspecting import libs with nm, you'll notice that the ld produced
import libs all have the same filename stem for the object files inside
the archive, while the ones from dlltool have unique stems. This is what
mixes them up when linking two of them with MS link.exe)
// Martin
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