1 files changed, 21 insertions, 14 deletions
diff --git a/compiler/semparallel.nim b/compiler/semparallel.nim
index fbcd6b6da..b04ba4657 100644
--- a/compiler/semparallel.nim
+++ b/compiler/semparallel.nim
@@ -128,10 +128,10 @@ template `?`(x): expr = x.renderTree
 proc checkLe(c: AnalysisCtx; a, b: PNode) =
   case proveLe(c.guards, a, b)
   of impUnknown:
-    localError(a.info, "cannot prove: " & ?a & " <= " & ?b)
+    localError(a.info, "cannot prove: " & ?a & " <= " & ?b & " (bounds check)")
   of impYes: discard
   of impNo:
-    localError(a.info, "can prove: " & ?a & " > " & ?b)
+    localError(a.info, "can prove: " & ?a & " > " & ?b & " (bounds check)")
 
 proc checkBounds(c: AnalysisCtx; arr, idx: PNode) =
   checkLe(c, arr.lowBound, idx)
@@ -156,19 +156,23 @@ proc addSlice(c: var AnalysisCtx; n: PNode; x, le, ri: PNode) =
 
 proc overlap(m: TModel; x,y,c,d: PNode) =
   #  X..Y and C..D overlap iff (X <= D and C <= Y)
-  case proveLe(m, x, d)
+  case proveLe(m, c, y)
   of impUnknown:
-    localError(x.info,
-      "cannot prove: $# > $#; required for ($#)..($#) disjoint from ($#)..($#)" %
-        [?x, ?d, ?x, ?y, ?c, ?d])
+    case proveLe(m, x, d)
+    of impNo: discard
+    of impUnknown, impYes:
+      localError(x.info,
+        "cannot prove: $# > $#; required for ($#)..($#) disjoint from ($#)..($#)" %
+            [?c, ?y, ?x, ?y, ?c, ?d])
   of impYes:
-    case proveLe(m, c, y)
+    case proveLe(m, x, d)
     of impUnknown:
       localError(x.info,
         "cannot prove: $# > $#; required for ($#)..($#) disjoint from ($#)..($#)" %
-          [?c, ?y, ?x, ?y, ?c, ?d])
+          [?x, ?d, ?x, ?y, ?c, ?d])
     of impYes:
-      localError(x.info, "($#)..($#) not disjoint from ($#)..($#)" % [?x, ?y, ?c, ?d])
+      localError(x.info, "($#)..($#) not disjoint from ($#)..($#)" %
+                [?c, ?y, ?x, ?y, ?c, ?d])
     of impNo: discard
   of impNo: discard
 
@@ -278,10 +282,12 @@ proc analyseCall(c: var AnalysisCtx; n: PNode; op: PSym) =
         slot.stride = min(slot.stride, incr)
     analyseSons(c, n)
   elif op.name.s == "[]" and op.fromSystem:
-    c.addSlice(n, n[1], n[2][1], n[2][2])
+    let slice = n[2].skipStmtList
+    c.addSlice(n, n[1], slice[1], slice[2])
     analyseSons(c, n)
   elif op.name.s == "[]=" and op.fromSystem:
-    c.addSlice(n, n[1], n[2][1], n[2][2])
+    let slice = n[2].skipStmtList
+    c.addSlice(n, n[1], slice[1], slice[2])
     analyseSons(c, n)
   else:
     analyseSons(c, n)
@@ -363,7 +369,7 @@ proc analyse(c: var AnalysisCtx; n: PNode) =
             else: internalError(it.info, "slot already has a lower bound")
         if not isSpawned: analyse(c, value)
   of nkCaseStmt: analyseCase(c, n)
-  of nkIfStmt, nkIfExpr: analyseIf(c, n)
+  of nkWhen, nkIfStmt, nkIfExpr: analyseIf(c, n)
   of nkWhileStmt:
     analyse(c, n.sons[0])
     # 'while true' loop?
@@ -395,8 +401,9 @@ proc transformSlices(n: PNode): PNode =
       result = copyNode(n)
       result.add opSlice.newSymNode
       result.add n[1]
-      result.add n[2][1]
-      result.add n[2][2]
+      let slice = n[2].skipStmtList
+      result.add slice[1]
+      result.add slice[2]
       return result
   if n.safeLen > 0:
     result = shallowCopy(n)