Re: [sr #107959] Libtool generates invalid .def files

[peda]

> URL:
>   <http://savannah.gnu.org/support/?107959>
>
*snip*
> Details:
>
> This is a follow-up from
> http://sourceware.org/bugzilla/show_bug.cgi?id=13710
>
> In the latest binutils snapshots, a change was applied which makes the
> processing of .def files for the win32/win64 targets more strict.
> According to
> the MSDN documentation at
> http://msdn.microsoft.com/en-us/library/d91k01sh%28v=vs.80%29.aspx all
> .def
> files must start with 'LIBRARY mylib.dll' followed by 'EXPORTS'.

Anyone using the MSDN as a reference in subtle matters such as this
must bring a fair bit of salt.  If you instead look at this

http://msdn.microsoft.com/en-us/library/30fw19zw%28v=vs.80%29.aspx

it is not needed to have any LIBRARY statement AT ALL.  And the MS
tools don't need any LIBRARY statement.  Breaking stuff arbitrarily
in binutils, using a weak MSDN reference as defence, is just crazy.

> Let's take this simple .def file for example:
>
> LIBRARY mylib.dll
> EXPORTS
> my_func
>
> If this .def file is processed by libtool then it automatically performs
this
> set of commands:
>
> libtool: link: if test "x`/bin/sed 1q .libs/libcairo.def`" = xEXPORTS; then
> cp .libs/libcairo.def .libs/libcairo-2.dll.def; else echo EXPORTS >
> .libs/libcairo-2.dll.def; cat .libs/libcairo.def >>
> .libs/libcairo-2.dll.def;
> fi
>
> This set of commands check if the first line of the .def file contains
> 'EXPORTS' and if this isn't the case, it automatically adds it.

That's not a completely accurate description, libtool is using the
EXPORTS header in the list of exported symbols as a key that this
is not a raw exports list, but instead a handwritten .def file.  So,
if libtool doesn't find EXPORTS on the first line it assumes that
the file is a raw list of exported symbols, which on windows means
that it will have to be modified into a .def file (by adding a line
with the EXPORTS header).

So, the fix in libtool is fairly straight-forward, but the case for
needing the LIBRARY line in the .def file is non-existant if you ask
me.

> Given the example .def file I mentioned earlier this will end up in:
>
> EXPORTS
> LIBRARY mylib.dll
> EXPORTS
> my_func
>
> This obviously is incorrect and can't be processed by binutils.
>
> Can libtool be changed so that it can process these kind of situations
> more properly?

Yes, of course it /can/, but IMHO it is binutils that needs to be un-broken.

Cheers,
Peter