work on some more

src/Core/MatchMerge.hs

@@ -78,7 +78,7 @@ mergeBranches :: [Branch] -> Unique ([Branch], Bool)
 -- No branches, no changes
 mergeBranches [] = return ([], False)
 -- Skip branches with complex guards (in the future we can optimize to merge guards)
-mergeBranches (b@(Branch [pat@PatCon{patConPatterns=ps}] guard):bs) | not (all isTrueGuard guard) = 
+mergeBranches (b@(Branch [pat@PatCon{patConPatterns=ps}] guard):bs) | not (all isTrueGuard guard) = do
   mergeBranches bs >>= (\(bs', v) -> return (b:bs', v))
 -- Branch with constructor pattern, try to merge it with the rest
 mergeBranches branches@(b@(Branch [pat@PatCon{patConPatterns=ps}] _): rst) = 
@@ -294,11 +294,11 @@ getReplaceMap discriminatingVars template p'
           -- introduce a new variable using the template's name, and map the other name to the template
           rp' = (tn2, Var tn1 InfoNone):rp in
       case pat' of 
-        Nothing -> -- Differs
-          -- Doesn't discriminate, but do need to propagate
+        Nothing -> -- 
+          -- Differs but doesn't discriminate
           if tn1 `notElem` discriminatingVars then (Nothing, rp') 
-          -- Introduce just a wild?
-          else (Just [PatWild], rp')
+
+          else error "MatchMerge: getReplaceMap. If a pattern discriminates than it should not be part of the template"
         Just _ -> -- Use the new pattern
           (pat', rp')
     (PatWild, PatWild) -> (Nothing, [])

test/cgen/match-merge.kk

@@ -12,6 +12,17 @@ fun reflow(e: list<int>)
     Cons(a, Nil) -> a.show.println
     Nil -> "Nothing".println
 
+fun no-guard(e: list<int>)
+  match e
+    Cons(a, b) | a == 0 -> b.println
+    Cons(b, c) | b == 1 -> c.println
+    Nil -> e.println
+
+fun named-subpatterns(e: list<list<int>>)
+  match e
+    Cons(n0 as Nil, Nil) -> n0.println
+    Cons(n1 as Cons(0, Nil), Nil) -> n1.println
+
 fun main()
   try {
     implicit-error-fallthrough([]) // Nothing
@@ -24,4 +35,12 @@ fun main()
   reflow([]) // Nothing
   reflow([3,2]) // 2
   reflow([2,1,2]) // 4
-  reflow([1]) // 1
+  reflow([1]) // 1
+
+  no-guard([0, 1]) // [1]
+  no-guard([1, 2]) // [2]
+  no-guard([]) // []
+
+  named-subpatterns([[]]) // []
+  named-subpatterns([[0]]) // [0]
+