configury: allow mpi extensions with no libraries

Do not require an archive when the OMPI_MPIEXT_<ext>_HAVE_OBJECT
macro is defined to 0.
See `ompi/mpiext/example/configure.m4`.

Allow some extensions to be built on OS X since the creation of
archives with no files is not permitted.

Refs. open-mpi/ompi#6205

Signed-off-by: Gilles Gouaillardet <gilles@rist.or.jp>
Signed-off-by: KAWASHIMA Takahiro <t-kawashima@jp.fujitsu.com>
Signed-off-by: Jeff Squyres <jsquyres@cisco.com>

config/ompi_ext.m4

@@ -5,7 +5,7 @@ dnl                         University Research and Technology
 dnl                         Corporation.  All rights reserved.
 dnl Copyright (c) 2009-2017 Cisco Systems, Inc.  All rights reserved
 dnl Copyright (c) 2011-2012 Oak Ridge National Labs.  All rights reserved.
-dnl Copyright (c) 2015-2018 Research Organization for Information Science
+dnl Copyright (c) 2015-2019 Research Organization for Information Science
 dnl                         and Technology (RIST).  All rights reserved.
 dnl Copyright (c) 2017      The University of Tennessee and The University
 dnl                         of Tennessee Research Foundation.  All rights
@@ -259,7 +259,8 @@ EOF
                                                   [OMPI_MPIEXT_C],
                                                   [OMPI_MPIEXT_MPIFH],
                                                   [OMPI_MPIEXT_USEMPI],
-                                                  [OMPI_MPIEXT_USEMPIF08])])])
+                                                  [OMPI_MPIEXT_USEMPIF08],
+                                                  [OMPI_MPIEXT_ARCHIVE])])])
 
     ###############
     # C Bindings
@@ -344,10 +345,10 @@ EOF
 
     OMPI_EXT_MAKE_DIR_LIST(OMPI_MPIEXT_ALL_SUBDIRS, $OMPI_MPIEXT_ALL)
 
-    OMPI_EXT_MAKE_LISTS(OMPI_MPIEXT_C, $OMPI_MPIEXT_C, c, c)
-    OMPI_EXT_MAKE_LISTS(OMPI_MPIEXT_MPIFH, $OMPI_MPIEXT_MPIFH, mpif-h, mpifh)
-    OMPI_EXT_MAKE_LISTS(OMPI_MPIEXT_USEMPI, $OMPI_MPIEXT_USEMPI, use-mpi, usempi)
-    OMPI_EXT_MAKE_LISTS(OMPI_MPIEXT_USEMPIF08, $OMPI_MPIEXT_USEMPIF08, use-mpi-f08, usempif08)
+    OMPI_EXT_MAKE_LISTS(OMPI_MPIEXT_C, $OMPI_MPIEXT_C, $OMPI_MPIEXT_ARCHIVE, c, c)
+    OMPI_EXT_MAKE_LISTS(OMPI_MPIEXT_MPIFH, $OMPI_MPIEXT_MPIFH, $OMPI_MPIEXT_ARCHIVE, mpif-h, mpifh)
+    OMPI_EXT_MAKE_LISTS(OMPI_MPIEXT_USEMPI, $OMPI_MPIEXT_USEMPI, $OMPI_MPIEXT_ARCHIVE, use-mpi, usempi)
+    OMPI_EXT_MAKE_LISTS(OMPI_MPIEXT_USEMPIF08, $OMPI_MPIEXT_USEMPIF08, $OMPI_MPIEXT_ARCHIVE, use-mpi-f08, usempif08)
 
     comps=`echo $OMPI_MPIEXT_C | sed -e 's/^[ \t]*//;s/[ \t]*$//;s/ /, /g'`
     AC_DEFINE_UNQUOTED([OMPI_MPIEXT_COMPONENTS], ["$comps"],
@@ -366,7 +367,8 @@ EOF
 #                                     (3) c_components_variable,
 #                                     (4) mpifh_components_variable,
 #                                     (5) usempi_components_variable,
-#                                     (6) usempif08_components_variable)
+#                                     (6) usempif08_components_variable,
+#                                     (7) archive_components_variable)
 #
 # - component_name is a single, naked string (no prefix)
 # - all others are naked component names (e.g., "example").  If an
@@ -386,7 +388,7 @@ AC_DEFUN([EXT_CONFIGURE_M4_CONFIG_COMPONENT],[
     OMPI_MPIEXT_$1_CONFIG([should_build=${should_build}], [should_build=0])
 
     AS_IF([test $should_build -eq 1],
-          [EXT_PROCESS_COMPONENT([$1], [$2], [$3], [$4], [$5], [$6])],
+          [EXT_PROCESS_COMPONENT([$1], [$2], [$3], [$4], [$5], [$6], [$7])],
           [EXT_PROCESS_DEAD_COMPONENT([$1], [$2])])
 ])
 
@@ -403,7 +405,8 @@ AC_DEFUN([EXT_CONFIGURE_M4_CONFIG_COMPONENT],[
 #                                       (3) c_components_variable,
 #                                       (4) mpifh_components_variable,
 #                                       (5) usempi_components_variable,
-#                                       (6) usempif08_components_variable)
+#                                       (6) usempif08_components_variable,
+#                                       (7) archive_components_variable)
 #
 # C bindings are mandatory.  Other bindings are optional / built if
 # they are found.  Here's the files that the m4 expects:
@@ -615,7 +618,7 @@ EOF
         m4_ifdef([OMPI_MPIEXT_]$1[_INCLUDE_MPIFH_IN_USEMPI],
                  [include_mpifh=OMPI_MPIEXT_$1_INCLUDE_MPIFH_IN_USEMPI],
                  [include_mpifh=1])
-        if test "$enabled_mpifh" = 1 && test "$include_mpifh" != 0; then
+        if test $enabled_mpifh -eq 1 && test $include_mpifh -ne 0; then
             mpifh_component_header="mpiext_${component}_mpifh.h"
             cat >> $mpiusempi_ext_h <<EOF
 #include "${mpifh_component_header_path}"
@@ -677,7 +680,7 @@ EOF
         m4_ifdef([OMPI_MPIEXT_]$1[_INCLUDE_MPIFH_IN_USEMPIF08],
                  [include_mpifh=OMPI_MPIEXT_$1_INCLUDE_MPIFH_IN_USEMPIF08],
                  [include_mpifh=1])
-        if test "$enabled_mpifh" = 1 && test "$include_mpifh" != 0; then
+        if test $enabled_mpifh -eq 1 && test $include_mpifh -ne 0; then
             mpifh_component_header="mpiext_${component}_mpifh.h"
             cat >> $mpiusempif08_ext_h <<EOF
 #include "${mpifh_component_header_path}"
@@ -704,6 +707,13 @@ EOF
              [echo "extern const ompi_mpiext_component_t ompi_mpiext_${component};" >> $outfile.extern
               echo "  &ompi_mpiext_${component}, " >> $outfile.struct])
 
+    m4_ifdef([OMPI_MPIEXT_]$1[_HAVE_OBJECT],
+             [have_object=OMPI_MPIEXT_$1_HAVE_OBJECT],
+             [have_object=1])
+    if test $have_object -ne 0; then
+        $7="$$7 $component"
+    fi
+
     # now add the flags that were set in the environment variables
     # framework_component_FOO (for example, the flags set by
     # m4_configure components)
@@ -804,7 +814,7 @@ AC_DEFUN([EXT_COMPONENT_BUILD_CHECK],[
         fi
     fi
 
-    AS_IF([test "$want_component" = "1"], [$2], [$3])
+    AS_IF([test $want_component -eq 1], [$2], [$3])
 ])
 
 
@@ -821,9 +831,10 @@ AC_DEFUN([OMPI_EXT_MAKE_DIR_LIST],[
 ])
 
 # OMPI_EXT_MAKE_LISTS((1) subst'ed variable prefix,
-#                     (2) shell list,
-#                     (3) bindings dir name,
-#                     (4) bindings suffix)
+#                     (2) shell list of extensions of which the bindings are enabled,
+#                     (3) shell list of extensions which needs libtool archive,
+#                     (4) bindings dir name,
+#                     (5) bindings suffix)
 #
 # Prefix every extension name with "mpiext/".
 # -------------------------------------------------------------------------
@@ -831,7 +842,7 @@ AC_DEFUN([OMPI_EXT_MAKE_LISTS],[
     # Make the directory list
     tmp=
     for item in $2 ; do
-       tmp="$tmp mpiext/$item/$3"
+       tmp="$tmp mpiext/$item/$4"
     done
     $1_DIRS=$tmp
     AC_SUBST($1_DIRS)
@@ -839,7 +850,12 @@ AC_DEFUN([OMPI_EXT_MAKE_LISTS],[
     # Make the list of libraries
     tmp=
     for item in $2 ; do
-       tmp="$tmp "'$(top_builddir)'"/ompi/mpiext/$item/$3/libmpiext_${item}_$4.la"
+        for item2 in $3 ; do
+            if test $item = $item2; then
+                tmp="$tmp "'$(top_builddir)'"/ompi/mpiext/$item/$4/libmpiext_${item}_$5.la"
+                break
+            fi
+        done
     done
     $1_LIBS=$tmp
     AC_SUBST($1_LIBS)

ompi/mpiext/example/configure.m4

@@ -3,6 +3,7 @@
 # Copyright (c) 2004-2009 The Trustees of Indiana University.
 #                         All rights reserved.
 # Copyright (c) 2012-2015 Cisco Systems, Inc.  All rights reserved.
+# Copyright (c) 2019      FUJITSU LIMITED.  All rights reserved.
 # $COPYRIGHT$
 #
 # Additional copyrights may follow
@@ -40,3 +41,17 @@ AC_DEFUN([OMPI_MPIEXT_example_NEED_INIT], [1])
 # By default, mpiext_example_mpifh.h is included in the source file
 # of the mpi_f08_ext module. To disable it, define this macro as 0.
 #AC_DEFUN([OMPI_MPIEXT_example_INCLUDE_MPIFH_IN_USEMPIF08], [0])
+
+# By default, $build_dir/ompi/mpiext/example/c/libmpiext_example_c.la
+# (Libtool archive) is added to the dependency list of libmpi.la.
+# This rule is the same for mpif-h and use-mpi-f08 bindings.
+# However, the ar command of macOS refuses to create an archive file
+# which does not contain any object files. If your extension has no
+# object files, i.e. only header files, define this macro as 0 so that
+# the *.la files are not added to the dependency lists.
+
+# NOTE: This is currently a single macro for the entire MPI extension.
+# I.e., your extension either has a library for each binding, or it has *no*
+# libraries for any of the bindings.  If finer-grained control is needed
+# someday, we may need to split this into multiple macros.
+#AC_DEFUN([OMPI_MPIEXT_example_HAVE_OBJECT], [0])