fixes #4910

compiler/semexprs.nim

@@ -1296,10 +1296,13 @@ proc takeImplicitAddr(c: PContext, n: PNode): PNode =
 proc asgnToResultVar(c: PContext, n, le, ri: PNode) {.inline.} =
   if le.kind == nkHiddenDeref:
     var x = le.sons[0]
-    if x.typ.kind == tyVar and x.kind == nkSym and x.sym.kind == skResult:
-      n.sons[0] = x # 'result[]' --> 'result'
-      n.sons[1] = takeImplicitAddr(c, ri)
-      x.typ.flags.incl tfVarIsPtr
+    if x.typ.kind == tyVar and x.kind == nkSym:
+      if x.sym.kind == skResult:
+        n.sons[0] = x # 'result[]' --> 'result'
+        n.sons[1] = takeImplicitAddr(c, ri)
+      if x.sym.kind != skParam:
+        # XXX This is hacky. See bug #4910.
+        x.typ.flags.incl tfVarIsPtr
       #echo x.info, " setting it for this type ", typeToString(x.typ), " ", n.info
 
 template resultTypeIsInferrable(typ: PType): untyped =

tests/cpp/tget_subsystem.nim

@@ -21,3 +21,11 @@ proc getSubsystem*[T](): ptr T {.
 
 let input: ptr Input = getSubsystem[Input]()
 
+
+# bug #4910
+
+proc foo() =
+  var ts: array[10, int]
+  for t in mitems(ts):
+     t = 123
+