Merge branch '958-improve-message-about-python-ply-v9_11' into 'v9_11'

Improve the error message about missing PLY Python package

See merge request !1920

configure

@@ -971,6 +971,7 @@ infodir
 docdir
 oldincludedir
 includedir
+runstatedir
 localstatedir
 sharedstatedir
 sysconfdir
@@ -1138,6 +1139,7 @@ datadir='${datarootdir}'
 sysconfdir='${prefix}/etc'
 sharedstatedir='${prefix}/com'
 localstatedir='${prefix}/var'
+runstatedir='${localstatedir}/run'
 includedir='${prefix}/include'
 oldincludedir='/usr/include'
 docdir='${datarootdir}/doc/${PACKAGE_TARNAME}'
@@ -1390,6 +1392,15 @@ do
   | -silent | --silent | --silen | --sile | --sil)
     silent=yes ;;
 
+  -runstatedir | --runstatedir | --runstatedi | --runstated \
+  | --runstate | --runstat | --runsta | --runst | --runs \
+  | --run | --ru | --r)
+    ac_prev=runstatedir ;;
+  -runstatedir=* | --runstatedir=* | --runstatedi=* | --runstated=* \
+  | --runstate=* | --runstat=* | --runsta=* | --runst=* | --runs=* \
+  | --run=* | --ru=* | --r=*)
+    runstatedir=$ac_optarg ;;
+
   -sbindir | --sbindir | --sbindi | --sbind | --sbin | --sbi | --sb)
     ac_prev=sbindir ;;
   -sbindir=* | --sbindir=* | --sbindi=* | --sbind=* | --sbin=* \
@@ -1527,7 +1538,7 @@ fi
 for ac_var in	exec_prefix prefix bindir sbindir libexecdir datarootdir \
 		datadir sysconfdir sharedstatedir localstatedir includedir \
 		oldincludedir docdir infodir htmldir dvidir pdfdir psdir \
-		libdir localedir mandir
+		libdir localedir mandir runstatedir
 do
   eval ac_val=\$$ac_var
   # Remove trailing slashes.
@@ -1680,6 +1691,7 @@ Fine tuning of the installation directories:
   --sysconfdir=DIR        read-only single-machine data [PREFIX/etc]
   --sharedstatedir=DIR    modifiable architecture-independent data [PREFIX/com]
   --localstatedir=DIR     modifiable single-machine data [PREFIX/var]
+  --runstatedir=DIR       modifiable per-process data [LOCALSTATEDIR/run]
   --libdir=DIR            object code libraries [EPREFIX/lib]
   --includedir=DIR        C header files [PREFIX/include]
   --oldincludedir=DIR     C header files for non-gcc [/usr/include]
@@ -12646,7 +12658,7 @@ fi
 $as_echo_n "checking for Python support... " >&6; }
 	      { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
-	      as_fn_error $? "Python required for dnssec-keymgr" "$LINENO" 5
+	      as_fn_error $? "Python >= 2.7 or >= 3.2 and the PLY package are required for dnssec-keymgr and other Python-based tools. PLY may be available from your OS package manager as python-ply or python3-ply; it can also be installed via pip. To build without Python/PLY, use --disable-python." "$LINENO" 5
 fi
 fi
 

configure.ac

@@ -310,7 +310,15 @@ AS_IF([test "$with_python" = "no"],
        AS_IF([test "X$PYTHON" = "X"],
 	     [AC_MSG_CHECKING([for Python support])
 	      AC_MSG_RESULT([no])
-	      AC_MSG_ERROR([Python required for dnssec-keymgr])])])
+	      AC_MSG_ERROR([m4_normalize(
+				[Python >= 2.7 or >= 3.2 and the PLY package
+                                 are required for dnssec-keymgr and other
+                                 Python-based tools. PLY may be
+                                 available from your OS package manager
+                                 as python-ply or python3-ply; it can also
+                                 be installed via pip. To build without
+                                 Python/PLY, use --disable-python.]
+			    )])])])
 
 PYTHON_TOOLS=''
 CHECKDS=''