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Avoid undefined behavior due to strict aliasing 

This does not make XCB conform to the C99+ strict aliasing rules, but it
does use attributes to prevent GCC and Clang from assuming the rules are
followed in the cases where XCB does violate them.

Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
This commit is contained in:
Demi Marie Obenour 2022-10-26 21:00:57 -04:00
parent 8adb5068af
commit 48dbb5b6ca
33 changed files with 64 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
configure.ac
View File

@ -15,7 +15,7 @@ AM_INIT_AUTOMAKE([foreign dist-xz])
AM_PATH_PYTHON([3.0]) AM_PATH_PYTHON([3.0])
# Set common system defines for POSIX extensions, such as _GNU_SOURCE # Set common system defines for POSIX extensions, such as _GNU_SOURCE
# Must be called before any macros that run the compiler (like AC_PROG_LIBTOOL) # Must be called before any macros that run the compiler (like LT_INIT)
# to avoid autoconf errors. # to avoid autoconf errors.
AC_USE_SYSTEM_EXTENSIONS AC_USE_SYSTEM_EXTENSIONS
AC_SYS_LARGEFILE AC_SYS_LARGEFILE
@ -27,6 +27,8 @@ LT_INIT([win32-dll])
# Require xorg-macros minimum of 1.18 - Initial version # Require xorg-macros minimum of 1.18 - Initial version
m4_ifndef([XORG_MACROS_VERSION], m4_ifndef([XORG_MACROS_VERSION],
[m4_fatal([must install xorg-macros 1.18 or later before running autoconf/autogen])]) [m4_fatal([must install xorg-macros 1.18 or later before running autoconf/autogen])])
XORG_TESTSET_CFLAG([XCB_CFLAGS], [-fno-strict-aliasing])
AC_SUBST([XCB_CFLAGS])
XORG_MACROS_VERSION(1.18) XORG_MACROS_VERSION(1.18)
XORG_DEFAULT_OPTIONS XORG_DEFAULT_OPTIONS
XORG_ENABLE_DEVEL_DOCS XORG_ENABLE_DEVEL_DOCS
@ -248,6 +250,23 @@ XCB_EXTENSION(XTest, yes)
XCB_EXTENSION(Xv, yes) XCB_EXTENSION(Xv, yes)
XCB_EXTENSION(XvMC, yes) XCB_EXTENSION(XvMC, yes)
AC_MSG_CHECKING([[if __attribute__((may_alias)) is supported]])
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
typedef struct x { int a; } __attribute__((may_alias)) x;
]])],[
AC_DEFINE([[XCB_MAY_ALIAS]], [[__attribute__((may_alias))]], [Define if __attribute__((may_alias)) works])
AC_MSG_RESULT([[yes]])
],[
AC_MSG_RESULT([[no]])
AC_MSG_CHECKING([[if -fno-strict-aliasing works]])[
case $XCB_CFLAGS in
*-fno-strict-aliasing*)]
AC_MSG_RESULT([[yes]])
AC_MSG_WARN([[may_alias not supported, programs must use -fno-strict-aliasing]]);;
*)
AC_MSG_RESULT([[no (flags are $XCB_CFLAGS)]])
AC_MSG_FAILURE([[No method of suppressing strict-aliasing found]]);;
[esac]])
AC_ARG_WITH(serverside-support, AS_HELP_STRING([--with-serverside-support], [Build with support for server-side usage of xcb. This is still EXPERIMENTAL! ABI/API may change! (default: no)]), [XCB_SERVERSIDE_SUPPORT=$withval], [XCB_SERVERSIDE_SUPPORT=no]) AC_ARG_WITH(serverside-support, AS_HELP_STRING([--with-serverside-support], [Build with support for server-side usage of xcb. This is still EXPERIMENTAL! ABI/API may change! (default: no)]), [XCB_SERVERSIDE_SUPPORT=$withval], [XCB_SERVERSIDE_SUPPORT=no])
AM_CONDITIONAL(XCB_SERVERSIDE_SUPPORT, test "x$XCB_SERVERSIDE_SUPPORT" = "xyes") AM_CONDITIONAL(XCB_SERVERSIDE_SUPPORT, test "x$XCB_SERVERSIDE_SUPPORT" = "xyes")

4
src/Makefile.am
View File

@ -4,7 +4,7 @@ EXTSOURCES = xproto.c \
bigreq.c \ bigreq.c \
xc_misc.c xc_misc.c
AM_CFLAGS = $(BASE_CFLAGS) $(NEEDED_CFLAGS) $(XDMCP_CFLAGS) AM_CFLAGS = $(BASE_CFLAGS) $(NEEDED_CFLAGS) $(XDMCP_CFLAGS) $(XCB_CFLAGS)
libxcb_la_LIBADD = $(NEEDED_LIBS) $(XDMCP_LIBS) libxcb_la_LIBADD = $(NEEDED_LIBS) $(XDMCP_LIBS)
libxcb_la_SOURCES = \ libxcb_la_SOURCES = \
xcb_conn.c xcb_out.c xcb_in.c xcb_ext.c xcb_xid.c \ xcb_conn.c xcb_out.c xcb_in.c xcb_ext.c xcb_xid.c \
@ -249,7 +249,7 @@ nodist_libxcb_ge_la_SOURCES = ge.c ge.h
endif endif
EXTHEADERS=$(EXTSOURCES:.c=.h) EXTHEADERS=$(EXTSOURCES:.c=.h)
xcbinclude_HEADERS = xcb.h xcbext.h xcbinclude_HEADERS = xcb.h xcbext.h config.h
if XCB_HAVE_WIN32 if XCB_HAVE_WIN32
xcbinclude_HEADERS += xcb_windefs.h xcbinclude_HEADERS += xcb_windefs.h
endif endif

14
src/c_client.py
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@ -279,7 +279,7 @@ def c_open(self):
_h('#include "xcb.h"') _h('#include "xcb.h"')
_c('#ifdef HAVE_CONFIG_H') _c('#ifdef HAVE_CONFIG_H')
_c('#include "config.h"') _hc('#include "config.h"')
_c('#endif') _c('#endif')
_c('#include <stdlib.h>') _c('#include <stdlib.h>')
_c('#include <stdalign.h>') _c('#include <stdalign.h>')
@ -1642,7 +1642,7 @@ def _c_iterator(self, name):
param[0], param[0],
' ' * (len(self.c_type) + 1 - len(param[0])), ' ' * (len(self.c_type) + 1 - len(param[0])),
param[2]) param[2])
_h('} %s;', self.c_iterator_type) _h('} XCB_MAY_ALIAS %s;', self.c_iterator_type)
_h_setlevel(1) _h_setlevel(1)
_c_setlevel(1) _c_setlevel(1)
@ -2254,7 +2254,7 @@ def _c_complex(self, force_packed = False):
if b.type.has_name: if b.type.has_name:
_h(' } %s;', b.c_field_name) _h(' } %s;', b.c_field_name)
_h('} %s%s;', 'XCB_PACKED ' if force_packed else '', self.c_type) _h('} %sXCB_MAY_ALIAS %s;', 'XCB_PACKED ' if force_packed else '', self.c_type)
def c_struct(self, name): def c_struct(self, name):
''' '''
@ -2756,7 +2756,7 @@ def _c_cookie(self, name):
_h(' **/') _h(' **/')
_h('typedef struct %s {', self.c_cookie_type) _h('typedef struct %s {', self.c_cookie_type)
_h(' unsigned int sequence;') _h(' unsigned int sequence;')
_h('} %s;', self.c_cookie_type) _h('} XCB_MAY_ALIAS %s;', self.c_cookie_type)
def _man_request(self, name, void, aux): def _man_request(self, name, void, aux):
param_fields = [f for f in self.fields if f.visible] param_fields = [f for f in self.fields if f.visible]
@ -2812,7 +2812,7 @@ def _man_request(self, name, void, aux):
f.write('.SS Reply datastructure\n') f.write('.SS Reply datastructure\n')
f.write('.nf\n') f.write('.nf\n')
f.write('.sp\n') f.write('.sp\n')
f.write('typedef %s %s {\n' % (self.reply.c_container, self.reply.c_type)) f.write('typedef XCB_MAY_ALIAS %s %s {\n' % (self.reply.c_container, self.reply.c_type))
struct_fields = [] struct_fields = []
maxtypelen = 0 maxtypelen = 0
@ -3389,7 +3389,7 @@ def c_event(self, name):
else: else:
# Typedef # Typedef
_h('') _h('')
_h('typedef %s %s;', _t(self.name + ('event',)), _t(name + ('event',))) _h('typedef XCB_MAY_ALIAS %s %s;', _t(self.name + ('event',)), _t(name + ('event',)))
# Create sizeof-function for eventcopies for compatibility reasons # Create sizeof-function for eventcopies for compatibility reasons
if self.c_need_sizeof: if self.c_need_sizeof:
@ -3424,7 +3424,7 @@ def c_error(self, name):
else: else:
# Typedef # Typedef
_h('') _h('')
_h('typedef %s %s;', _t(self.name + ('error',)), _t(name + ('error',))) _h('typedef XCB_MAY_ALIAS %s %s;', _t(self.name + ('error',)), _t(name + ('error',)))
# Main routine starts here # Main routine starts here

6
src/xcb.h
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@ -53,8 +53,14 @@ extern "C" {
#ifdef __GNUC__ #ifdef __GNUC__
#define XCB_PACKED __attribute__((__packed__)) #define XCB_PACKED __attribute__((__packed__))
#ifndef XCB_MAY_ALIAS
#define XCB_MAY_ALIAS __attribute__((may_alias))
#endif
#else #else
#define XCB_PACKED #define XCB_PACKED
#ifndef XCB_MAY_ALIAS
#define XCB_MAY_ALIAS
#endif
#endif #endif
/** /**

2
xcb-composite.pc.in
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@ -8,4 +8,4 @@ Description: XCB Composite Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb xcb-xfixes Requires.private: xcb xcb-xfixes
Libs: -L${libdir} -lxcb-composite Libs: -L${libdir} -lxcb-composite
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-damage.pc.in
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@ -8,4 +8,4 @@ Description: XCB Damage Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb xcb-xfixes Requires.private: xcb xcb-xfixes
Libs: -L${libdir} -lxcb-damage Libs: -L${libdir} -lxcb-damage
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-dbe.pc.in
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@ -8,4 +8,4 @@ Description: XCB Double Buffer Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-dbe Libs: -L${libdir} -lxcb-dbe
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-dpms.pc.in
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@ -8,4 +8,4 @@ Description: XCB DPMS Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-dpms Libs: -L${libdir} -lxcb-dpms
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-dri2.pc.in
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@ -8,4 +8,4 @@ Description: XCB DRI2 Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-dri2 Libs: -L${libdir} -lxcb-dri2
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-dri3.pc.in
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@ -8,4 +8,4 @@ Description: XCB DRI3 Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-dri3 Libs: -L${libdir} -lxcb-dri3
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-ge.pc.in
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@ -8,4 +8,4 @@ Description: XCB GenericEvent Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-ge Libs: -L${libdir} -lxcb-ge
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-glx.pc.in
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@ -8,4 +8,4 @@ Description: XCB GLX Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-glx Libs: -L${libdir} -lxcb-glx
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-present.pc.in
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@ -8,4 +8,4 @@ Description: XCB Present Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb xcb-randr xcb-xfixes xcb-sync xcb-dri3 Requires.private: xcb xcb-randr xcb-xfixes xcb-sync xcb-dri3
Libs: -L${libdir} -lxcb-present Libs: -L${libdir} -lxcb-present
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-randr.pc.in
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@ -8,4 +8,4 @@ Description: XCB RandR Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb xcb-render Requires.private: xcb xcb-render
Libs: -L${libdir} -lxcb-randr Libs: -L${libdir} -lxcb-randr
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-record.pc.in
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@ -8,4 +8,4 @@ Description: XCB Record Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-record Libs: -L${libdir} -lxcb-record
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-render.pc.in
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@ -8,4 +8,4 @@ Description: XCB Render Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-render Libs: -L${libdir} -lxcb-render
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-res.pc.in
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@ -8,4 +8,4 @@ Description: XCB X-Resource Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-res Libs: -L${libdir} -lxcb-res
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-screensaver.pc.in
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@ -8,4 +8,4 @@ Description: XCB Screensaver Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-screensaver Libs: -L${libdir} -lxcb-screensaver
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-shape.pc.in
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@ -8,4 +8,4 @@ Description: XCB Shape Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-shape Libs: -L${libdir} -lxcb-shape
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-shm.pc.in
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@ -8,4 +8,4 @@ Description: XCB Shm Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-shm Libs: -L${libdir} -lxcb-shm
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-sync.pc.in
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@ -8,4 +8,4 @@ Description: XCB Sync Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-sync Libs: -L${libdir} -lxcb-sync
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-xevie.pc.in
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@ -8,4 +8,4 @@ Description: XCB Xevie Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-xevie Libs: -L${libdir} -lxcb-xevie
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-xf86dri.pc.in
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@ -8,4 +8,4 @@ Description: XCB XFree86-DRI Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-xf86dri Libs: -L${libdir} -lxcb-xf86dri
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-xfixes.pc.in
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@ -8,4 +8,4 @@ Description: XCB XFixes Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb xcb-render xcb-shape Requires.private: xcb xcb-render xcb-shape
Libs: -L${libdir} -lxcb-xfixes Libs: -L${libdir} -lxcb-xfixes
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-xinerama.pc.in
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@ -8,4 +8,4 @@ Description: XCB Xinerama Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-xinerama Libs: -L${libdir} -lxcb-xinerama
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-xinput.pc.in
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@ -8,4 +8,4 @@ Description: XCB XInput Extension (EXPERIMENTAL)
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb xcb-xfixes Requires.private: xcb xcb-xfixes
Libs: -L${libdir} -lxcb-xinput Libs: -L${libdir} -lxcb-xinput
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-xkb.pc.in
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@ -8,4 +8,4 @@ Description: XCB Keyboard Extension (EXPERIMENTAL)
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-xkb Libs: -L${libdir} -lxcb-xkb
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-xprint.pc.in
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@ -8,4 +8,4 @@ Description: XCB Xprint Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-xprint Libs: -L${libdir} -lxcb-xprint
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-xselinux.pc.in
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@ -8,4 +8,4 @@ Description: XCB SELinux Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-xselinux Libs: -L${libdir} -lxcb-xselinux
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-xtest.pc.in
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@ -8,4 +8,4 @@ Description: XCB XTEST Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb Requires.private: xcb
Libs: -L${libdir} -lxcb-xtest Libs: -L${libdir} -lxcb-xtest
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-xv.pc.in
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@ -8,4 +8,4 @@ Description: XCB Xv Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb xcb-shm Requires.private: xcb xcb-shm
Libs: -L${libdir} -lxcb-xv Libs: -L${libdir} -lxcb-xv
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb-xvmc.pc.in
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@ -8,4 +8,4 @@ Description: XCB XvMC Extension
Version: @PACKAGE_VERSION@ Version: @PACKAGE_VERSION@
Requires.private: xcb xcb-xv Requires.private: xcb xcb-xv
Libs: -L${libdir} -lxcb-xvmc Libs: -L${libdir} -lxcb-xvmc
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@

2
xcb.pc.in
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@ -10,4 +10,4 @@ Version: @PACKAGE_VERSION@
Requires.private: @NEEDED@ Requires.private: @NEEDED@
Libs: -L${libdir} -lxcb Libs: -L${libdir} -lxcb
Libs.private: @LIBS@ Libs.private: @LIBS@
Cflags: -I${includedir} Cflags: -I${includedir} @XCB_CFLAGS@