Use pkg-config's pkg.m4

* configure.ac: Use pkg-config's pkg.m4, rather than reinventing it.
Add explicit AC_SUBST's where needed.

* autogen.sh (progs): Add pkg-config.
(pkg_config_min): New variable.

* INSTALL.REPO: Mention pkg-config.

* etc/PROBLEMS: Mention a related issue that can occur with a local automake.

5 files changed, 28 insertions, 58 deletions

diff --git a/ChangeLog b/ChangeLog
index c9ca6bfa9c1..91e51d681d2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2014-05-02  Glenn Morris  <rgm@gnu.org>
 
+        * configure.ac: Use pkg-config's pkg.m4, rather than reinventing it.
+        Add explicit AC_SUBST's where needed.
+        * autogen.sh (progs): Add pkg-config.
+        (pkg_config_min): New variable.
+
         * configure.ac (AC_CONFIG_MACRO_DIR): Use it.
 
         * autogen.sh (get_version): Handle no leading whitespace.
diff --git a/INSTALL.REPO b/INSTALL.REPO
index 36ab928673d..c1617e781c1 100644
--- a/INSTALL.REPO
+++ b/INSTALL.REPO
@@ -12,6 +12,8 @@ autoconf  - at least the version specified near the start of
   configure.ac (in the AC_PREREQ command).
 automake  - at least the version specified near the start of
   configure.ac (in the AM_INIT_AUTOMAKE command).
+pkg-config - at least version specified in the PKG_PROG_PKG_CONFIG
+  command in configure.ac
 makeinfo  - not strictly necessary, but highly recommended, so that
   you can build the manuals.
 
diff --git a/autogen.sh b/autogen.sh
index 255a4d75ba6..84230b56016 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -32,7 +32,7 @@
 
 ## Tools we need:
 ## Note that we respect the values of AUTOCONF etc, like autoreconf does.
-progs="autoconf automake"
+progs="autoconf automake pkg-config"
 
 ## Minimum versions we need:
 autoconf_min=`sed -n 's/^ *AC_PREREQ(\([0-9\.]*\)).*/\1/p' configure.ac`
@@ -41,6 +41,7 @@ autoconf_min=`sed -n 's/^ *AC_PREREQ(\([0-9\.]*\)).*/\1/p' configure.ac`
 ## AM_INIT_AUTOMAKE call.
 automake_min=`sed -n 's/^ *AM_INIT_AUTOMAKE(\([0-9\.]*\)).*/\1/p' configure.ac`
 
+pkg_config_min=`sed -n 's/^ *PKG_PROG_PKG_CONFIG(\([0-9\.]*\)).*/\1/p' configure.ac`
 
 ## $1 = program, eg "autoconf".
 ## Echo the version string, eg "2.59".
diff --git a/configure.ac b/configure.ac
index 837a619d8a6..27312cac3ab 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1339,65 +1339,12 @@ AC_SUBST(LIB_MATH)
 AC_DEFINE_UNQUOTED(SYSTEM_TYPE, "$SYSTEM_TYPE",
   [The type of system you are compiling for; sets `system-type'.])
 
+m4_pattern_forbid([^PKG_])
 
 pre_PKG_CONFIG_CFLAGS=$CFLAGS
 pre_PKG_CONFIG_LIBS=$LIBS
 
-AC_PATH_PROG(PKG_CONFIG, pkg-config, no)
-
-dnl This function definition taken from Gnome 2.0
-dnl PKG_CHECK_MODULES(GSTUFF, gtk+-2.0 >= 1.3 glib = 1.3.4, action-if, action-not)
-dnl defines GSTUFF_LIBS, GSTUFF_CFLAGS, see pkg-config man page
-dnl also defines GSTUFF_PKG_ERRORS on error
-AC_DEFUN([PKG_CHECK_MODULES], [
-  succeeded=no
-
-  if test "$PKG_CONFIG" = "no" ; then
-     ifelse([$4], , [AC_MSG_ERROR([
-      *** The pkg-config script could not be found. Make sure it is in your path, or give the full name of pkg-config with the PKG_CONFIG environment variable or --with-pkg-config-prog.  Or see http://www.freedesktop.org/software/pkgconfig to get pkg-config.])], [$4])
-  else
-     PKG_CONFIG_MIN_VERSION=0.9.0
-     if "$PKG_CONFIG" --atleast-pkgconfig-version $PKG_CONFIG_MIN_VERSION; then
-        AC_MSG_CHECKING(for $2)
-
-        if "$PKG_CONFIG" --exists "$2" 2>&AS_MESSAGE_LOG_FD &&
-           $1_CFLAGS=`"$PKG_CONFIG" --cflags "$2" 2>&AS_MESSAGE_LOG_FD` &&
-           $1_LIBS=`"$PKG_CONFIG" --libs "$2" 2>&AS_MESSAGE_LOG_FD`; then
-            edit_cflags="
-              s,///*,/,g
-              s/^/ /
-              s/ -I/ $isystem/g
-              s/^ //
-            "
-            $1_CFLAGS=`AS_ECHO(["$$1_CFLAGS"]) | sed -e "$edit_cflags"`
-            $1_LIBS=`AS_ECHO(["$$1_LIBS"]) | sed -e 's,///*,/,g'`
-            AC_MSG_RESULT([yes CFLAGS='$$1_CFLAGS' LIBS='$$1_LIBS'])
-            succeeded=yes
-        else
-            AC_MSG_RESULT(no)
-            $1_CFLAGS=""
-            $1_LIBS=""
-            ## If we have a custom action on failure, don't print errors, but
-            ## do set a variable so people can do so.  Do it in a subshell
-            ## to capture any diagnostics in invoking pkg-config.
-            $1_PKG_ERRORS=`("$PKG_CONFIG" --print-errors "$2") 2>&1`
-            ifelse([$4], ,echo "$$1_PKG_ERRORS",)
-        fi
-
-        AC_SUBST($1_CFLAGS)
-        AC_SUBST($1_LIBS)
-     else
-        echo "*** Your version of pkg-config is too old. You need version $PKG_CONFIG_MIN_VERSION or newer."
-        echo "*** See http://www.freedesktop.org/software/pkgconfig"
-     fi
-  fi
-
-  if test $succeeded = yes; then
-     ifelse([$3], , :, [$3])
-  else
-     ifelse([$4], , [AC_MSG_ERROR([Library requirements ($2) not met; consider adjusting the PKG_CONFIG_PATH environment variable if your libraries are in a nonstandard prefix so pkg-config can find them.])], [$4])
-  fi
-])
+PKG_PROG_PKG_CONFIG(0.9.0)
 
 HAVE_SOUND=no
 if test "${with_sound}" != "no"; then
@@ -2415,6 +2362,8 @@ if test "${with_dbus}" = "yes"; then
      DBUS_OBJ=dbusbind.o
    fi
 fi
+AC_SUBST(DBUS_CFLAGS)
+AC_SUBST(DBUS_LIBS)
 AC_SUBST(DBUS_OBJ)
 
 dnl GSettings has been tested under GNU/Linux only.
@@ -3268,7 +3217,6 @@ if test "${HAVE_X11}" = "yes"; then
       [AC_CHECK_LIB(Xrandr, XRRGetScreenResources, HAVE_XRANDR=yes)])
     if test $HAVE_XRANDR = yes; then
       XRANDR_LIBS=-lXrandr
-      AC_SUBST(XRANDR_LIBS)
     fi
   fi
   if test $HAVE_XRANDR = yes; then
@@ -3283,6 +3231,8 @@ if test "${HAVE_X11}" = "yes"; then
     AC_DEFINE(HAVE_XRANDR, 1, [Define to 1 if you have the XRandr extension.])
   fi
 fi
+AC_SUBST(XRANDR_CFLAGS)
+AC_SUBST(XRANDR_LIBS)
 
 ### Use Xinerama (-lXinerama) if available
 HAVE_XINERAMA=no
@@ -3297,13 +3247,14 @@ if test "${HAVE_X11}" = "yes"; then
       [AC_CHECK_LIB(Xinerama, XineramaQueryExtension, HAVE_XINERAMA=yes)])
     if test $HAVE_XINERAMA = yes; then
       XINERAMA_LIBS=-lXinerama
-      AC_SUBST(XINERAMA_LIBS)
     fi
   fi
   if test $HAVE_XINERAMA = yes; then
     AC_DEFINE(HAVE_XINERAMA, 1, [Define to 1 if you have the Xinerama extension.])
   fi
 fi
+AC_SUBST(XINERAMA_CFLAGS)
+AC_SUBST(XINERAMA_LIBS)
 
 
 ### Use libxml (-lxml2) if available
diff --git a/etc/PROBLEMS b/etc/PROBLEMS
index 58c2ceaf68c..3d5349c2793 100644
--- a/etc/PROBLEMS
+++ b/etc/PROBLEMS
@@ -2223,6 +2223,17 @@ If you do, please send it to bug-gnu-emacs@gnu.org so we can list it here.
 
 * Build-time problems
 
+** Autogen.sh / Autoreconf
+
+*** Running `autogen.sh' or `autoreconf' fails with an error of the form
+"possibly undefined macro: PKG_CONFIG".  This indicates that the version
+of aclocal that you are using cannot find the pkg.m4 file that
+pkg-config provides.  If you installed your own version of automake in
+a non-standard location /prefix, then add a line to the
+/prefix/share/aclocal/dirlist file (create the file if necessary)
+that gives the location of the directory that contains pkg.m4
+(e.g. /usr/share/aclocal).
+
 ** Configuration
 
 *** `configure' warns ``accepted by the compiler, rejected by the preprocessor''.