Quick Fix:

Constant expressions used in when statements and tuple indexing are properly evaluated now

Even further step tested to be OK:

```nimrod
proc semConstExpr(c: PContext, n: PNode): PNode = 
  result = semAndEvalConstExpr(c, n)
```

2 files changed, 2 insertions, 2 deletions

diff --git a/compiler/semexprs.nim b/compiler/semexprs.nim
index 1b4f778a8..5f4c7749a 100755
--- a/compiler/semexprs.nim
+++ b/compiler/semexprs.nim
@@ -747,7 +747,7 @@ proc semSubscript(c: PContext, n: PNode, flags: TExprFlags): PNode =
     checkSonsLen(n, 2)
     n.sons[0] = makeDeref(n.sons[0])
     # [] operator for tuples requires constant expression:
-    n.sons[1] = semConstExpr(c, n.sons[1])
+    n.sons[1] = semAndEvalConstExpr(c, n.sons[1])
     if skipTypes(n.sons[1].typ, {tyGenericInst, tyRange, tyOrdinal}).kind in
         {tyInt..tyInt64}: 
       var idx = getOrdValue(n.sons[1])
diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index ce870a3ad..decc8a2d7 100755
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -19,7 +19,7 @@ proc semWhen(c: PContext, n: PNode): PNode =
     case it.kind
     of nkElifBranch: 
       checkSonsLen(it, 2)
-      var e = semConstBoolExpr(c, it.sons[0])
+      var e = semAndEvalConstExpr(c, it.sons[0])
       if (e.kind != nkIntLit): InternalError(n.info, "semWhen")
       if (e.intVal != 0) and (result == nil): 
         result = semStmt(c, it.sons[1]) # do not open a new scope!