***(
Bug discovered 12/22/09.

CUI_DagNode::stackArguments() checks the wrong UNSTACKABLE flag for the
second argument resulting in a missed rewrite.

Resolved in alpha92b.
)
set show timing off .

mod CUI-BUG is
  sort Foo .
  ops a b c d 1 : -> Foo .
  op f : Foo Foo -> Foo  [id: 1] .
  op g : Foo -> Foo .

  rl b => c .
  rl c => d .
endm

rew f(a, g(b)) .

***(
first pass:
f does not rewrite - marked unrewritable
f stacks a and g(b)
a does not rewrite - marked unrewritable
g(b) does not rewrite - marked unrewritable
a does not stack anything and is unrewritable - marked unstackable
g stacks b
b rewrites to c and we rebuild f(a, g(c)) with only the a node shared
with the previous dag

second pass:
f is unrewritable
f cannot stack a because it is unstackable
f cannot stack g(c) because we check the wrong unstackable flag

thus we miss c => d
)

mod CUI-BUG2 is
  sort Foo .
  ops a b c d 1 : -> Foo .
  op f : Foo Foo -> Foo  [id: 1] .
  op g : Foo -> Foo .

  rl b => c .
  rl g(c) => d .
endm

rew f(a, g(b)) .
