| Message ID | 1467157426-6461-1-git-send-email-mdroth@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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... 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 <thuth@redhat.com>
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 <thuth@redhat.com> Thanks!
Quoting Michael Roth (2016-06-28 18:43:46) > 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 $vss_win32_include. For the > same reason, this also enforces a new dependency on -isystem support > in the C/C++ compiler when building QGA with VSS enabled. > > Cc: Thomas Huth <thuth@redhat.com> > Cc: Stefan Weil <sw@weilnetz.de> > Cc: Paolo Bonzini <pbonzini@redhat.com> > Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> Thanks, applied to qga tree: https://github.com/mdroth/qemu/commits/qga > --- > configure | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/configure b/configure > index e14e907..2d84bc5 100755 > --- a/configure > +++ b/configure > @@ -4049,13 +4049,13 @@ fi > > if test "$mingw32" = "yes" -a "$guest_agent" != "no" -a "$vss_win32_sdk" != "no" ; then > case "$vss_win32_sdk" in > - "") vss_win32_include="-I$source_path" ;; > + "") vss_win32_include="-isystem $source_path" ;; > *\ *) # The SDK is installed in "Program Files" by default, but we cannot > # handle path with spaces. So we symlink the headers into ".sdk/vss". > - vss_win32_include="-I$source_path/.sdk/vss" > + vss_win32_include="-isystem $source_path/.sdk/vss" > symlink "$vss_win32_sdk/inc" "$source_path/.sdk/vss/inc" > ;; > - *) vss_win32_include="-I$vss_win32_sdk" > + *) vss_win32_include="-isystem $vss_win32_sdk" > esac > cat > $TMPC << EOF > #define __MIDL_user_allocate_free_DEFINED__ > -- > 1.9.1 > >
diff --git a/configure b/configure index e14e907..2d84bc5 100755 --- a/configure +++ b/configure @@ -4049,13 +4049,13 @@ fi if test "$mingw32" = "yes" -a "$guest_agent" != "no" -a "$vss_win32_sdk" != "no" ; then case "$vss_win32_sdk" in - "") vss_win32_include="-I$source_path" ;; + "") vss_win32_include="-isystem $source_path" ;; *\ *) # The SDK is installed in "Program Files" by default, but we cannot # handle path with spaces. So we symlink the headers into ".sdk/vss". - vss_win32_include="-I$source_path/.sdk/vss" + vss_win32_include="-isystem $source_path/.sdk/vss" symlink "$vss_win32_sdk/inc" "$source_path/.sdk/vss/inc" ;; - *) vss_win32_include="-I$vss_win32_sdk" + *) vss_win32_include="-isystem $vss_win32_sdk" esac cat > $TMPC << EOF #define __MIDL_user_allocate_free_DEFINED__
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. Cc: Thomas Huth <thuth@redhat.com> Cc: Stefan Weil <sw@weilnetz.de> Cc: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> --- configure | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)