Bugfix: aliases to generic types were not considered implicit generic parameters

compiler/semtypes.nim

@@ -887,6 +887,9 @@ proc liftParamType(c: PContext, procKind: TSymKind, genericParams: PNode,
       # disable the bindOnce behavior for the type class
       result = liftingWalk(paramType.base, true)
 
+  of tyAlias:
+    result = liftingWalk(paramType.base)
+
   of tySequence, tySet, tyArray, tyOpenArray,
      tyVar, tyLent, tyPtr, tyRef, tyProc:
     # XXX: this is a bit strange, but proc(s: seq)

tests/statictypes/tstatictypes.nim

@@ -0,0 +1,17 @@
+discard """
+nimout: '''
+staticAlialProc instantiated with 4
+staticAlialProc instantiated with 6
+'''
+"""
+
+type
+  StaticTypeAlias = static[int]
+
+proc staticAliasProc(s: StaticTypeAlias) =
+  static: echo "staticAlialProc instantiated with ", s + 1
+
+staticAliasProc 1+2
+staticAliasProc 3
+staticAliasProc 5
+