fixes #23945; type checking for whenvm expresssions

compiler/semexprs.nim

@@ -2684,6 +2684,8 @@ proc semWhen(c: PContext, n: PNode, semCheck = true): PNode =
         if semCheck:
           it[0] = semExpr(c, it[0], flags)
           typ = commonType(c, typ, it[0].typ)
+          if typ != nil and typ.kind != tyUntyped:
+            it[0] = fitNode(c, typ, it[0], it[0].info)
         if result == nil:
           result = it[0]
     else: illFormedAst(n, c.config)
@@ -2694,6 +2696,11 @@ proc semWhen(c: PContext, n: PNode, semCheck = true): PNode =
     if n.len == 1:
       result.add(newTree(nkElse, newNode(nkStmtList)))
 
+    if $result.typ == "seq[uint8]":
+      echo " -> ", result.typ
+      echo semCheck
+      echo n.renderTree
+
 proc semSetConstr(c: PContext, n: PNode, expectedType: PType = nil): PNode =
   result = newNodeI(nkCurly, n.info)
   result.typ = newTypeS(tySet, c)

lib/pure/md5.nim

@@ -100,32 +100,19 @@ proc decode(dest: var openArray[uint8], src: openArray[uint32]) =
     dest[i+3] = uint8(src[j] shr 24 and 0xff'u32)
     inc(i, 4)
 
-template slice(s: string, a, b): openArray[uint8] =
-  when nimvm:
-    # toOpenArray is not implemented in VM
-    var s2 = newSeq[uint8](s.len)
-    for i in 0 ..< s2.len:
-      s2[i] = uint8(s[i])
-    s2
-  else:
-    s.toOpenArrayByte(a, b)
-
 template slice(s: cstring, a, b): openArray[uint8] =
   when nimvm:
     # toOpenArray is not implemented in VM
-    slice($s, a, b)
+    toOpenArrayByte($s, a, b)
   else:
     when defined(js):
       # toOpenArrayByte for cstring is not implemented in JS
-      slice($s, a, b)
+      toOpenArrayByte($s, a, b)
     else:
       s.toOpenArrayByte(a, b)
 
 template slice(s: openArray[uint8], a, b): openArray[uint8] =
-  when nimvm:
-    s[a .. b]
-  else:
-    s.toOpenArray(a, b)
+  s.toOpenArray(a, b)
 
 const useMem = declared(copyMem)