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cond-short.mk revision 1.1 
      1 # $NetBSD: cond-short.mk,v 1.1 2020/06/28 09:42:40 rillig Exp $
      2 #
      3 # Demonstrates that in conditions, the right-hand side of an && or ||
      4 # is evaluated even though it cannot influence the result.
      5 #
      6 # This is unexpected for several reasons:
      7 #
      8 # 1.  The manual page says: "bmake will only evaluate a conditional as
      9 #     far as is necessary to determine its value."
     10 #
     11 # 2.  It differs from the way that these operators are evaluated in
     12 #     almost all other programming languages.
     13 #
     14 # 3.  In cond.c there are lots of doEval variables.
     15 #
     16 
     17 .if 0 && ${echo "unexpected and" 1>&2 :L:sh}
     18 .endif
     19 
     20 .if 1 && ${echo "expected and" 1>&2 :L:sh}
     21 .endif
     22 
     23 .if 1 || ${echo "unexpected or" 1>&2 :L:sh}
     24 .endif
     25 
     26 .if 0 || ${echo "expected or" 1>&2 :L:sh}
     27 .endif
     28 
     29 # The following paragraphs demonstrate the workaround.
     30 
     31 .if 0
     32 .  if ${echo "unexpected nested and" 1>&2 :L:sh}
     33 .  endif
     34 .endif
     35 
     36 .if 1
     37 .elif ${echo "unexpected nested or" 1>&2 :L:sh}
     38 .endif
     39 
     40 all:
     41 	@:;:
     42