Quoting Thomas Huth (2016-06-29 03:27:26) > On 29.06.2016 01:43, Michael Roth wrote: > > As of e4650c81, we do w32 builds with -Werror enabled. Unfortunately > > for cases where we enable VSS support in qemu-ga, we still have > > warnings generated by VSS includes that ship as part of the Microsoft > > VSS SDK. > > > > We can selectively address a number of these warnings using > > > > #pragma GCC diagnostic ignored ... > > > > but at least one of these: > > > > warning: ‘typedef’ was ignored in this declaration > > > > resulting from declarations of the form: > > > > typedef struct Blah { ... }; > > > > does not provide a specific command-line/pragma option to disable > > warnings of the sort. > > > > To allow VSS builds to succeed, the next-best option is disabling > > these warnings on a per-file basis. pragmas like #pragma GCC > > system_header can be used to declare subsequent includes/declarations > > as being exempt from normal warnings, but this must be done within > > a header file. > > > > Since we don't control the VSS SDK, we'd need to rely on a > > intermediate header include to accomplish this, and > > since different objects in the VSS link target rely on different > > headers from the VSS SDK, this would become somewhat of a rat's nest > > (though not totally unmanageable). > > > > The next step up in granularity is just marking the entire VSS > > SDK include path as system headers via -isystem. This is a bit more > > heavy-handed, but since this SDK hasn't changed since 2005, there's > > likely little to be gained from selectively disabling warnings > > anyway, so we implement that approach here. > > > > This fixes the -Werror failures in both the configure test and the > > qga build due to shared reliance on $vss_win32_include. For the > > same reason, this also enforces a new dependency on -isystem support > > in the C/C++ compiler when building QGA with VSS enabled. > > Did we ever support any non-GCC-based compiler for building QGA? I don't > think so, but in the worst case, we could later add a check whether the > compiler supports that parameter, too...
Not really, but I think it's possible to bootstrap clang using mingw, which is probably a reasonable option to keep open. That was the main reason I wanted to point out the new dependency, but it turns out clang supports -isystem anyway so a check/fallback in configure (like we have for #pragma GCC diagnostic) is probably not not needed atm. The other possibility is a native MSVC compile, but I doubt that works as is (heavy usage of unistd.h, for instance), and I'm not aware of any good reason to make it work. > > Anyway, I think your patch is a nice and clean way to deal with the > error messages from these headers, so: > > Reviewed-by: Thomas Huth <th...@redhat.com> Thanks!