libevent2022/configure.m4: always invoke sub-configure

In order to make "make distclean" (and friends) work, we need to
*always* invoke the embedded configure script -- even if we know that
we're not going to use this component.

But in cases where we know we're not going to use this component, we
also need to avoid the side effects of the code path that is used when
we *do* want to use this component.  So split the two possibilities
into two different macros:

1. MCA_opal_event_libevent2022_FAKE_CONFIG: which does almost nothing
   except invoke the underlying "configure" script.
2. MCA_opal_event_libevent2022_REAL_CONFIG: which does all the real
   work (including invoking the underlying "configure" script).

Signed-off-by: Jeff Squyres <[email protected]>

Author: jsquyres

opal/mca/event/libevent2022/configure.m4

@@ -35,8 +35,8 @@ AC_DEFUN([MCA_opal_event_libevent2022_POST_CONFIG], [
            # copied from libevent's Makefile.am.
 
            AC_CONFIG_COMMANDS([opal/mca/event/libevent2022/libevent/include/event2/event-config.h],
-                              [libevent_basedir="opal/mca/event/libevent2022"
-                               libevent_file="$libevent_basedir/libevent/include/event2/event-config.h"
+                              [opal_event_libevent2022_basedir="opal/mca/event/libevent2022"
+                               libevent_file="$opal_event_libevent2022_basedir/libevent/include/event2/event-config.h"
                                rm -f "$libevent_file.new"
                                cat > "$libevent_file.new" <<EOF
 /* event2/event-config.h
@@ -56,7 +56,7 @@ EOF
 
                                sed -e 's/#define /#define _EVENT_/' \
                                    -e 's/#undef /#undef _EVENT_/' \
-                                   -e 's/#ifndef /#ifndef _EVENT_/' < "$libevent_basedir/libevent/config.h" >> "$libevent_file.new"
+                                   -e 's/#ifndef /#ifndef _EVENT_/' < "$opal_event_libevent2022_basedir/libevent/config.h" >> "$libevent_file.new"
                                echo "#endif" >> "$libevent_file.new"
 
                                # Only make a new .h libevent_file if the
@@ -75,7 +75,7 @@ EOF
 
            # Add some stuff to CPPFLAGS so that the rest of the source
            # tree can be built
-           libevent_file=$libevent_basedir/libevent
+           libevent_file=$opal_event_libevent2022_basedir/libevent
            CPPFLAGS="-I$OPAL_TOP_SRCDIR/$libevent_file -I$OPAL_TOP_SRCDIR/$libevent_file/include $CPPFLAGS"
            AS_IF([test "$OPAL_TOP_BUILDDIR" != "$OPAL_TOP_SRCDIR"],
                  [CPPFLAGS="-I$OPAL_TOP_BUILDDIR/$libevent_file/include $CPPFLAGS"])
@@ -87,25 +87,47 @@ dnl MCA_event_libevent2022_CONFIG([action-if-can-compile],
 dnl                              [action-if-cant-compile])
 dnl ------------------------------------------------
 AC_DEFUN([MCA_opal_event_libevent2022_CONFIG],[
+    AC_CONFIG_FILES([opal/mca/event/libevent2022/Makefile])
+    opal_event_libevent2022_basedir="opal/mca/event/libevent2022"
+
     # We know that the external event component will be configured
     # before this one because of its priority.  This component is only
     # needed if the external component was not successful in selecting
     # itself.
     AC_MSG_CHECKING([if event external component succeeded])
     AS_IF([test "$opal_event_external_support" = "yes"],
           [AC_MSG_RESULT([yes])
-           AC_MSG_NOTICE([event:external succeeded, so this component will be skipped])
-           $2],
+           AC_MSG_NOTICE([event:external succeeded, so this component will be configured, but then will be skipped])
+           MCA_opal_event_libevent2022_FAKE_CONFIG($2)],
           [AC_MSG_RESULT([no])
            AC_MSG_NOTICE([event:external failed, so this component will be used])
-           MCA_opal_event_libevent2022_BACKEND_CONFIG($1, $2)])
+           MCA_opal_event_libevent2022_REAL_CONFIG($1, $2)])
 ])
 
-AC_DEFUN([MCA_opal_event_libevent2022_BACKEND_CONFIG],[
-    OPAL_VAR_SCOPE_PUSH([CFLAGS_save CPPFLAGS_save libevent_file event_args libevent_happy])
+dnl
+dnl This macro is invoked when event:external is going to be used (and
+dnl this component is *not* going to be used).
+dnl
+dnl $1: action if this component can compile
+dnl (we still invoke $1 so that "make distclean" and friends will work)
+dnl
+AC_DEFUN([MCA_opal_event_libevent2022_FAKE_CONFIG],[
+    MCA_opal_event_libevent2022_SUB_CONFIGURE([], [], [])
+    AC_MSG_NOTICE([remember: event:external will be used; this component was configured, but will be skipped])
+    $1
+])
 
-    AC_CONFIG_FILES([opal/mca/event/libevent2022/Makefile])
-    libevent_basedir="opal/mca/event/libevent2022"
+dnl
+dnl This macro has a bunch of side effects.  It is only meant to be
+dnl invoked when this component is going to be used (i.e., when
+dnl event:external is *not* going to be used).  If this macro is invoked
+dnl when event:external is used, Terrible Things will happen.
+dnl
+dnl $1: action if this component can compile
+dnl $2: action if this component cannot compile
+dnl
+AC_DEFUN([MCA_opal_event_libevent2022_REAL_CONFIG],[
+    OPAL_VAR_SCOPE_PUSH([CFLAGS_save CPPFLAGS_save libevent_file event_args libevent_happy])
 
     CFLAGS_save="$CFLAGS"
     CFLAGS="$OPAL_CFLAGS_BEFORE_PICKY $OPAL_VISIBILITY_CFLAGS"
@@ -175,14 +197,14 @@ AC_DEFUN([MCA_opal_event_libevent2022_BACKEND_CONFIG],[
 
     AC_MSG_RESULT([$event_args])
 
+    # Invoke the embedded configure script.
     # We define "random" to be "opal_random" so that Libevent will not
     # use random(3) internally (and potentially unexpectedly perturb
     # values returned by rand(3) to the application).
-
     CPPFLAGS="$CPPFLAGS -Drandom=opal_random"
-    OPAL_CONFIG_SUBDIR([$libevent_basedir/libevent],
-        [$event_args $opal_subdir_args 'CPPFLAGS=$CPPFLAGS'],
-        [libevent_happy="yes"], [libevent_happy="no"])
+    MCA_opal_event_libevent2022_SUB_CONFIGURE([$event_args],
+                                              [libevent_happy="yes"],
+                                              [libevent_happy="no"])
     if test "$libevent_happy" = "no"; then
         AC_MSG_WARN([Event library failed to configure])
         AC_MSG_ERROR([Cannot continue])
@@ -200,26 +222,34 @@ AC_DEFUN([MCA_opal_event_libevent2022_BACKEND_CONFIG],[
     # the value in the generated libevent/config.h (NOT
     # libevent/include/event2/event-config.h!).  Otherwise, set it to
     # 0.
-    libevent_file=$libevent_basedir/libevent/config.h
-
-    # If we are not building the internal libevent, then indicate that
-    # this component should not be built.  NOTE: we still did all the
-    # above configury so that all the proper GNU Autotools
-    # infrastructure is setup properly (e.g., w.r.t. SUBDIRS=libevent in
-    # this directory's Makefile.am, we still need the Autotools "make
-    # distclean" infrastructure to work properly).
-
-    AS_IF([test "$with_libevent" != "internal" && test -n "$with_libevent" && test "$with_libevent" != "yes"],
-          [AC_MSG_WARN([using an external libevent; disqualifying this component])
-           libevent_happy=no],
-
-          [AS_IF([test "$libevent_happy" = "yes" && test -r $libevent_file],
-            [OPAL_HAVE_WORKING_EVENTOPS=`grep HAVE_WORKING_EVENTOPS $libevent_file | awk '{print [$]3 }'`
-              $1],
-            [$2
-              OPAL_HAVE_WORKING_EVENTOPS=0])
-          ]
-    )
+    libevent_file=$opal_event_libevent2022_basedir/libevent/config.h
+
+    AS_IF([test "$libevent_happy" = "yes" && test -r $libevent_file],
+          [OPAL_HAVE_WORKING_EVENTOPS=`grep HAVE_WORKING_EVENTOPS $libevent_file | awk '{print [$]3 }'`
+           $1],
+          [$2
+           OPAL_HAVE_WORKING_EVENTOPS=0])
 
     OPAL_VAR_SCOPE_POP
 ])
+
+dnl Call configure in the embedded libevent.
+dnl
+dnl We still do this so that all the proper GNU Autotools
+dnl infrastructure is setup properly (e.g., w.r.t. SUBDIRS=libevent in
+dnl this directorys Makefile.am, we still need the Autotools "make
+dnl distclean" infrastructure to work properly).
+dnl
+dnl $1: extra configure arguments
+dnl $2: action on success
+dnl $3: action on failure
+dnl
+AC_DEFUN([MCA_opal_event_libevent2022_SUB_CONFIGURE],[
+    # We define "random" to be "opal_random" so that Libevent will not
+    # use random(3) internally (and potentially unexpectedly perturb
+    # values returned by rand(3) to the application).
+
+    OPAL_CONFIG_SUBDIR([$opal_event_libevent2022_basedir/libevent],
+        [$1 $opal_subdir_args 'CPPFLAGS=$CPPFLAGS'],
+        [$2], [$3])
+])