bin/43669: another problem parsing conditionals in make

[dholland%eecs.harvard.edu@localhost]

>Number:         43669
>Category:       bin
>Synopsis:       another problem parsing conditionals in make
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jul 26 07:50:00 +0000 2010
>Originator:     David A. Holland
>Release:        NetBSD 5.99.29 (make from today though)
>Organization:
>Environment:
System: NetBSD valkyrie 5.99.29 NetBSD 5.99.29 (VALKYRIE) #1: Sat May 29 
23:00:44 EDT 2010  dholland@valkyrie:/usr/src/sys/arch/amd64/compile/VALKYRIE 
amd64
Architecture: amd64
Machine: x86_64
>Description:

Make horks unexpectedly on some conditionals and not others that ought
to be entirely equivalent.

Consider the following two makefiles:

   ---- Makefile1 ----
moo:
.if defined(MOO) && !empty(MOO:Myes)
        @echo moo
.else
        @echo no moo
.endif
   ---- Makefile2 ----
moo:
.if defined(MOO) && !empty(MOO:Myes) && 1
        @echo moo
.else
        @echo no moo
.endif
   ---- (end) ----

and observe the following behavior:

   valkyrie% make -f Makefile1 MOO=yes
   moo
   valkyrie% make -f Makefile1 MOO=no
   no moo
   valkyrie% make -f Makefile1 MOO=
   no moo
   valkyrie% make -f Makefile1 
   no moo
   valkyrie% make -f Makefile2 MOO=yes
   moo
   valkyrie% make -f Makefile2 MOO=no
   no moo
   valkyrie% make -f Makefile2 MOO=
   no moo
   valkyrie% make -f Makefile2 
   make: "/tmp/test/Makefile2" line 2: Malformed conditional (defined(MOO) && 
!empty(MOO:Myes) && 1)
   make: Fatal errors encountered -- cannot continue

   make: stopped in /tmp/test
   Exit 1
   valkyrie% 

I really can't think of any sane reason that make should accept the
conditional in Makefile1 when MOO isn't defined but not the form in
Makefile2.

For that matter, I can't think of any reason make should reject the
conditional in Makefile2; both defined(MOO) and !empty(MOO:Myes)
should yield false when MOO is undefined, not something like an empty
string that would legitimately upset make.

However, sanity isn't make's long suit. :-)

>How-To-Repeat:

as above

>Fix:

no idea.

(well, other than restructure the whole thing as I've proposed in the past)