Tests for v1 closed generics/static issues (#8572)

* Add tests to confirm https://github.com/nim-lang/Nim/issues/7231 is fixed.

* Add test for closed https://github.com/nim-lang/Nim/issues/6137

* Add test for https://github.com/nim-lang/Nim/issues/7141

tests/generics/t6137.nim

@@ -0,0 +1,29 @@
+discard """
+  action: "reject"
+  line: 29
+  errormsg: "\'vectFunc\' doesn't have a concrete type, due to unspecified generic parameters."
+"""
+
+type
+  # simple vector of declared fixed length
+  vector[N : static[int]] = array[0..N-1, float]
+
+proc `*`[T](x: float, a: vector[T]): vector[T] =
+  # multiplication by scalar
+  for ii in 0..high(a):
+    result[ii] = a[ii]*x
+
+let
+  # define a vector of length 3
+  x: vector[3] = [1.0, 3.0, 5.0]
+
+proc vectFunc[T](x: vector[T]): vector[T] {.procvar.} =
+  # Define a vector function
+  result = 2.0*x
+
+proc passVectFunction[T](g: proc(x: vector[T]): vector[T], x: vector[T]): vector[T] =
+  # pass a vector function as input in another procedure
+  result = g(x)
+
+let
+  xNew = passVectFunction(vectFunc,x)