fix #16898 #17621 (#17628)

* fix #16898
* fix #17621

* Update compiler/semtypes.nim

tests/lent/t16898.nim

@@ -0,0 +1,31 @@
+discard """
+  errormsg: "invalid type: 'lent QuadraticExt' in this context: 'proc (r: var QuadraticExt, a: lent QuadraticExt, b: lent QuadraticExt){.noSideEffect, gcsafe, locks: 0.}' for proc"
+"""
+
+# bug #16898
+type
+  Fp[N: static int, T] = object
+    big: array[N, T]
+
+type
+  QuadraticExt* = concept x
+    ## Quadratic Extension concept (like complex)
+    type BaseField = auto
+    x.c0 is BaseField
+    x.c1 is BaseField
+
+{.experimental:"views".}
+
+func prod(r: var QuadraticExt, a, b: lent QuadraticExt) =
+  discard
+
+type
+  Fp2[N: static int, T] = object
+    c0, c1: Fp[N, T]
+
+# This should be passed by reference,
+# but concepts do not respect the 24 bytes rule
+# or `byref` pragma.
+var r, a, b: Fp2[6, uint64]
+
+prod(r, a, b)

tests/lent/t17621.nim

@@ -0,0 +1,15 @@
+discard """
+  errormsg: "invalid type: 'lent Test' in this context: 'proc (self: lent Test)' for proc"
+"""
+
+# bug #17621
+{.experimental: "views".}
+
+type Test = ref object
+  foo: int
+
+proc modify(self: lent Test) =
+  self.foo += 1
+
+let test = Test(foo: 12)
+modify(test)