Restore the Nim's 0.14 proper handling of generic aliases

A more efficient implementation is possible by restoring the old
lifting ot tyGenericInvocation to tyGenericInst in liftTypeParam,
but this fix will suffice for now.

fixes #5087
fixes #5602
fixes #5641
fixes #5570

tests/generics/t5570.nim

@@ -0,0 +1,27 @@
+discard """
+  nimout: "type uint32\ntype uint32"
+  output: "(weight: 17.0, color: 100)"
+"""
+
+import macros
+
+type
+  BaseFruit[T] = object of RootObj
+    color: T
+
+  Banana[T] = object of BaseFruit[uint32]
+    weight: T
+
+macro printTypeName(typ: typed): untyped =
+  echo "type ", getType(typ).repr
+
+proc setColor[K](self: var BaseFruit[K], c: int) =
+  printTypeName(self.color)
+  self.color = uint32(c)
+
+var x: Banana[float64]
+x.weight = 17
+printTypeName(x.color)
+x.setColor(100)
+echo x
+

tests/generics/t5602_inheritence.nim

@@ -0,0 +1,18 @@
+discard """
+  output: "seq[float]\n0"
+"""
+
+# https://github.com/nim-lang/Nim/issues/5602
+
+import typetraits
+
+type
+  Foo[T] = object of RootObj
+  Bar[T] = object of Foo[seq[T]]
+
+proc p[T](f: Foo[T]): T =
+  echo T.name
+
+var s: Bar[float]
+echo p(s).len # the bug was: p(s) should return seq[float], but returns float instead
+

tests/generics/tmapping_generic_alias.nim

@@ -0,0 +1,28 @@
+discard """
+output: '''type(c) = GenAlias[system.int]
+T = int
+seq[int]
+'''
+"""
+
+import typetraits
+
+type
+  Gen[T] = object
+    x: T
+
+  GenAlias[T] = Gen[seq[T]]
+
+proc f1[T](x: Gen[T]) =
+  echo T.name
+
+proc f2[T](x: GenAlias[T]) =
+  echo "type(c) = ", type(x).name
+  echo "T = ", T.name
+  f1 x
+
+let
+  y = Gen[seq[int]](x: @[10])
+
+f2 y
+

tests/generics/tparam_binding.nim

@@ -0,0 +1,28 @@
+discard """
+  errormsg: "got (ref Matrix[2, 2, system.float], ref Matrix[2, 1, system.float])"
+  line: 27
+"""
+
+type
+  Matrix[M,N: static[int]; T: SomeReal] = distinct array[0..(M*N - 1), T]
+
+let a = new Matrix[2,2,float]
+let b = new Matrix[2,1,float]
+
+proc foo[M,N: static[int],T](a: ref Matrix[M, N, T], b: ref Matrix[M, N, T])=
+  discard
+
+foo(a, a)
+
+proc bar[M,N: static[int],T](a: ref Matrix[M, M, T], b: ref Matrix[M, N, T])=
+  discard
+
+bar(a, b)
+bar(a, a)
+
+proc baz[M,N: static[int],T](a: ref Matrix[N, N, T], b: ref Matrix[M, N, T])=
+  discard
+
+baz(a, a)
+baz(a, b)
+