[MLton-commit] r5168

[Matthew Fluet]

WordXVector.equals (and, consequently, Const.equals) was judging empty
vectors of different element sizes as being equal.  This would allow
constantPropagation (and probably commonSubexp) to equate empty
strings of different sizes, yielding a type-incorrect program.

The solution is simply: WordXVector.equals now judges vectors as equal
if they have the same elementSize and equal elements.


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U   mlton/trunk/mlton/atoms/word-x-vector.fun

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Modified: mlton/trunk/mlton/atoms/word-x-vector.fun
===================================================================
--- mlton/trunk/mlton/atoms/word-x-vector.fun	2007-02-11 20:34:10 UTC (rev 5167)
+++ mlton/trunk/mlton/atoms/word-x-vector.fun	2007-02-11 21:17:01 UTC (rev 5168)
@@ -45,7 +45,9 @@
 
 val layout = Layout.str o toString
 
-fun equals (v, v') = Vector.equals (elements v, elements v', WordX.equals)
+fun equals (v, v') = 
+    WordSize.equals (elementSize v, elementSize v')
+    andalso Vector.equals (elements v, elements v', WordX.equals)
 
 fun forall (v, f) = Vector.forall (elements v, f)