bugfix: don't treat generic types with different static params as the same type

compiler/sigmatch.nim

@@ -979,6 +979,9 @@ proc typeRel(c: var TCandidate, f, aOrig: PType, doBind = true): TTypeRelation =
   of tyStatic:
     if aOrig.kind == tyStatic:
       result = typeRel(c, f.lastSon, a)
+      if result != isNone and f.n != nil:
+        if not exprStructuralEquivalent(f.n, a.n):
+          result = isNone
       if result != isNone: put(c.bindings, f, aOrig)
     else:
       result = isNone

tests/types/tisopr.nim

@@ -34,3 +34,20 @@ type
 yes s.items is Iter[TNumber]
 no  s.items is Iter[float]
 
+type
+  Foo[N: static[int], T] = object
+    field: array[1..N, T]
+
+  Bar[T] = Foo[4, T]
+  Baz[N: static[int]] = Foo[N, float]
+
+no Foo[2, float] is Foo[3, float]
+no Foo[2, float] is Foo[2, int]
+
+yes Foo[4, string] is Foo[4, string]
+yes Bar[int] is Foo[4, int]
+yes Foo[4, int] is Bar[int]
+
+no Foo[4, int] is Baz[4]
+yes Foo[4, float] is Baz[4]
+