Backport #27632, part 1

p4raw-id: //depot/metaconfig@27658

diff --git a/U/installdirs/inc_version_list.U b/U/installdirs/inc_version_list.U
index 44382ec..ae6834f 100644 (file)
--- a/U/installdirs/inc_version_list.U
+++ b/U/installdirs/inc_version_list.U
@@ -10,9 +10,9 @@
 ?RCS:
 ?RCS: $Log: inc_version_list.U,v $
 ?RCS:
-?MAKE:inc_version_list inc_version_list_init: cat sed Getfile perl5 \
-       version api_versionstring rm Myread archname prefix sitelib_stem \
-       exe_ext
+?MAKE:inc_version_list inc_version_list_init d_inc_version_list: cat sed \
+       Getfile perl5 version api_versionstring rm Myread archname \
+       prefix sitelib_stem exe_ext
 ?MAKE: -pick add $@ %<
 ?Y:TOP
 ?S:inc_version_list:
@@ -35,6 +35,10 @@
 ?S:    each item is enclosed in double quotes and separated by commas, 
 ?S:    suitable for use in the PERL_INC_VERSION_LIST initialization.
 ?S:.
+?S:d_inc_version_list:
+?S:    This variable conditionally defines PERL_INC_VERSION_LIST.
+?S:    It is set to undef when PERL_INC_VERSION_LIST is empty.
+?S:.
 ?C:PERL_INC_VERSION_LIST:
 ?C:    This variable specifies the list of subdirectories in over
 ?C:    which perl.c:incpush() and lib/lib.pm will automatically
@@ -135,9 +139,12 @@ case "$ans" in
 esac
 case "$inc_version_list" in
 ''|' ') 
-       inc_version_list_init='0';;
+       inc_version_list_init='0'
+       d_inc_version_list="$undef"
+       ;;
 *)     inc_version_list_init=`echo $inc_version_list |
                $sed -e 's/^/"/' -e 's/ /","/g' -e 's/$/",0/'`
+       d_inc_version_list="$define"
        ;;
 esac
 $rm -f getverlist