On 08/31/2018 11:57 AM, Nick Wellnhofer wrote: > On 25/05/2018 17:46, Michael Haubenwallner wrote: >> When an application using libxml2 does not enable multithreaded support >> for itself, we provide the singlethreaded variables, eventually tagged >> with dllimport. So even when we build the multithreaded libxml2, our >> singlethreaded variables still eventually need the dllexport tag. > > I don't understand the issue. Do you mean an application linked with a DLL > configured without thread support and compiled with single-thread headers, > and THEN swapping the DLL with a multi-thread version? I'm not sure whether > this should be supported.
Actually it's the other way round: The xml library is configured with thread support, but the application is created without thread support - with the application in question being gettext (as of version 0.19.7, but it's the same even in gettext master still). Without patching, gettext does explicitly use the --disable-auto-import linker flag on Cygwin and MinGW, relying on symbols to be dllexport'ed, see http://git.savannah.gnu.org/cgit/gettext.git/tree/m4/woe32-dll.m4?h=v0.19.7 However, the Cygwin distro currently does modify this m4/woe32-dll.m4 to stay with auto-import enabled, simply to get a working gettext package. So even when thread support is enabled in xml, it still is useful in single threaded applications - and xml should support this use case. Right now, LIBXML_THREAD_ENABLED is defined in xmlversion.h only if the *application* does enable threads, otherwise the single threaded xml symbols are declared - which are not dllexport'ed when thread support is configured for libxml, yet they are still there but auto-imported. However, another variant might be to declare the threaded symbols when xml is *configured* with threads enabled, not depending on whether the application has threads enabled. Beyond that, omitting the single threaded symbols from the dll may make sense, but that would require a SONAME bump. HTH, /haubi/ _______________________________________________ xml mailing list, project page http://xmlsoft.org/ xml@gnome.org https://mail.gnome.org/mailman/listinfo/xml
