[boost] [iostreams] [RudbekAssociates] msvc regressions

From: David Deakins (ddeakins_at_[hidden])
Date: 2007-02-28 12:45:06

Douglas Gregor wrote:
> |iostreams|
>   bzip2_test:  intel-linux-9.0  msvc-7.1  msvc-8.0
>   file_descriptor_test:  gcc-cygwin-3.4.4
>   gzip_test:  intel-linux-9.0  msvc-7.1  msvc-8.0
>   zlib_test:  intel-linux-9.0  msvc-7.1  msvc-8.0
> 

I spent a little bit of time looking into the msvc-7.1 and msvc-8.0 
regressions for this library.  It looks like the zlib and bzip2 
libraries used in these tests are being built from source files and it 
appears that there are some omissions in the iostreams jamfile for 
properly building them as DLLs in Windows.

For zlib, there just needs to be a <link>shared:<define>ZLIB_DLL in its 
build requirements so that the zlib source files use the __declspec 
keyword on functions that should be exported.  Without this, no 
functions are exported and the import library file is not created (thus 
the link errors).

With bzip2, the basic problem is the same but its sources use a .DEF 
file rather than __declspec (at least in the 1.0.4 sources that I looked 
at).  Adding <link>shared:<def-file>$(BZIP2_SOURCE)/libbz2.def properly 
included the DEF file that gives the exports, but revealed another 
problem.  The DEF file has a 'LIBRARY LIBBZ2' line in it which wants to 
give the DLL the name libbz2.DLL.  Unfortunately the iostreams jam file 
typically calls the library something like 
boost_bzip2-vc80-mt-gd-1_34.DLL and specifies an /OUT directive to the 
linker to ask for this name.  At least on my machine with VC8, the /OUT 
directive overrides the LIBRARY rule enough to make the intended 
boost_bzip2-vc80-mt-gd-1_34.DLL file, but not enough to get this name 
into the import .LIB file that boost_iostreams links to.  As a result, 
the iostreams library will compile and link, but will fail trying locate 
libbz2.DLL (instead of the correct boost_bzip2-vc80-mt-gd-1_34.DLL). 
The only way I could easily resolve this was to comment out the LIBRARY 
rule in the libbz2.DEF file in the bzip2 sources like so:

; LIBRARY     LIBBZ2

With this change and the patches to the iostreams jamfile, building zlib 
and bzip2 from sources works correctly and the 3 tests pass.  I attached 
a patch for jamfile.v2 in libs\iostream\build with my changes.  It might 
be good to put a note about the bzip2 .DEF file change in the iostreams 
documentation.

Incidently, using <def-file> revealed a small issue in msvc.jam related 
to DEF file paths that have spaces in them.  The linker command does not 
put quotes around the DEF path like it does with most of the other 
parameters, and as a result DEF paths with spaces will cause the link to 
fail.  I also included a patch to msvc.jam to add quotes around DEF file 
paths.

Thanks,
-Dave