Abort if Tcl support was configured and no tcl shell was found.

This is required because the value is substituted into the pltcl_*mod
scripts.

config/tcl.m4

-# $PostgreSQL: pgsql/config/tcl.m4,v 1.5 2003/11/29 19:51:17 pgsql Exp $
+# $PostgreSQL: pgsql/config/tcl.m4,v 1.6 2008/07/23 17:07:49 petere Exp $
 
 # Autoconf macros to check for Tcl related things
 
 
 AC_DEFUN([PGAC_PATH_TCLSH],
-         [AC_PATH_PROGS(TCLSH, [tclsh tcl])])
+[AC_PATH_PROGS(TCLSH, [tclsh tcl])
+if test x"$TCLSH" = x""; then
+  AC_MSG_ERROR([Tcl shell not found])
+fi
+])
 
 
 # PGAC_PATH_TCLCONFIGSH([SEARCH-PATH])

configure

@@ -25032,6 +25032,12 @@ fi
   test -n "$TCLSH" && break
 done
+if test x"$TCLSH" = x""; then
+  { { echo "$as_me:$LINENO: error: Tcl shell not found" >&5
+echo "$as_me: error: Tcl shell not found" >&2;}
+   { (exit 1); exit 1; }; }
+fi
+
 { echo "$as_me:$LINENO: checking for tclConfig.sh" >&5
 echo $ECHO_N "checking for tclConfig.sh... $ECHO_C" >&6; }
 # Let user override test

doc/src/sgml/installation.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/installation.sgml,v 1.310 2008/06/05 19:56:09 alvherre Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/installation.sgml,v 1.311 2008/07/23 17:07:50 petere Exp $ -->
 
 <chapter id="installation">
  <title><![%standalone-include[<productname>PostgreSQL</>]]>
@@ -1447,7 +1447,8 @@ su - postgres
        <listitem>
         <para>
          Full path to the Tcl interpreter.  This will be used to
-         determine the dependencies for building PL/Tcl.
+         determine the dependencies for building PL/Tcl, and it will
+         be substituted into Tcl scripts.
         </para>
        </listitem>
       </varlistentry>