fix #12864 static params were mutating arg types during sigmatch; fix #12713 ; refs #13529 (#13976)

* fix #12864 static params were mutating arg types during sigmatch

* fix test

* fix StaticParam

* also fixes #12713; added test case

tests/statictypes/tstatictypes.nim

@@ -170,3 +170,49 @@ var
   s: StringValue16
 
 echo s
+
+block: #13529
+  block:
+    type Foo[T: static type] = object
+    var foo: Foo["test"]
+    doAssert $foo == "()"
+    doAssert foo.T is string
+    static: doAssert foo.T == "test"
+    doAssert not compiles(
+      block:
+        type Foo2[T: static type] = object
+          x: T)
+
+  block:
+    type Foo[T: static[float]] = object
+    var foo: Foo[1.2]
+    doAssert $foo == "()"
+    doAssert foo.T == 1.2
+
+  block: # routines also work
+    proc fun(a: static) = (const a2 = a)
+    fun(1)
+    fun(1.2)
+  block: # routines also work
+    proc fun(a: static type) = (const a2 = a)
+    fun(1)
+    fun(1.2)
+
+  block: # this also works
+    proc fun[T](a: static[T]) = (const a2 = a)
+    fun(1)
+    fun(1.2)
+
+block: # #12713
+  block:
+    type Cell = object
+      c: int
+    proc test(c: static string) = discard #Remove this and it compiles
+    proc test(c: Cell) = discard
+    test Cell(c: 0)
+  block:
+    type Cell = object
+      c: int
+    proc test(c: static string) = discard #Remove this and it compiles
+    proc test(c: Cell) = discard
+    test Cell()