I've tested extension building against an installed copy of the release candidate in a non-threaded configuration and it fails because reentr.inc is included unconditionally even when threads are not enabled:
#include "reentr.inc"
.^
%CC-F-NOINCLFILEF, Cannot find file "reentr.inc" specified in #include directive.
at line number 3600 in file PERL_ROOT:[LIB.VMS_AXP.5_8_4.CORE]perl.h;1
I'm pretty sure this is different from how it used to be, but in any case the attached patch unconditionally copies both reentr.inc and reentr.h to the archcore directory, from whence installperl will pick them up and install them.
This is only for maint; blead will need something different as it appears there is no longer a reentr.inc there.
--- vms/descrip_mms.template;-0 Thu Apr 8 12:15:57 2004
+++ vms/descrip_mms.template Thu Apr 8 15:37:04 2004
@@ -293,11 +293,7 @@
ac7 = $(ARCHCORE)pad.h $(ARCHCORE)patchlevel.h $(ARCHCORE)perl.h
ac8 = $(ARCHCORE)perlapi.h $(ARCHCORE)perlio.h $(ARCHCORE)perlsdio.h
ac9 = $(ARCHCORE)perlsfio.h $(ARCHCORE)perlvars.h $(ARCHCORE)perly.h $(ARCHCORE)pp.h
-.ifdef THREADED
ac10 = $(ARCHCORE)pp_proto.h $(ARCHCORE)proto.h $(ARCHCORE)reentr.h
$(ARCHCORE)reentr.inc $(ARCHCORE)regcomp.h
-.else
-ac10 = $(ARCHCORE)pp_proto.h $(ARCHCORE)proto.h $(ARCHCORE)regcomp.h
-.endif
ac11 = $(ARCHCORE)regexp.h $(ARCHCORE)regnodes.h $(ARCHCORE)scope.h
.ifdef SOCKARCH
ac12 = $(ARCHCORE)sv.h $(ARCHCORE)thrdvar.h $(SOCKARCH)
@@ -1392,14 +1388,12 @@
$(ARCHCORE)proto.h : proto.h
@ If F$Search("$(ARCHDIR)CORE.dir").eqs."" Then Create/Directory $(ARCHCORE)
Copy/NoConfirm/Log $(MMS$SOURCE) $(ARCHCORE)
-.ifdef THREADED
$(ARCHCORE)reentr.h : reentr.h
@ If F$Search("$(ARCHDIR)CORE.dir").eqs."" Then Create/Directory $(ARCHCORE)
Copy/NoConfirm/Log $(MMS$SOURCE) $(ARCHCORE)
$(ARCHCORE)reentr.inc : reentr.inc
@ If F$Search("$(ARCHDIR)CORE.dir").eqs."" Then Create/Directory $(ARCHCORE)
Copy/NoConfirm/Log $(MMS$SOURCE) $(ARCHCORE)
-.endif
$(ARCHCORE)regcomp.h : regcomp.h
@ If F$Search("$(ARCHDIR)CORE.dir").eqs."" Then Create/Directory $(ARCHCORE)
Copy/NoConfirm/Log $(MMS$SOURCE) $(ARCHCORE)
