[infer/py][easy] adding support for the open builtin

Summary: Adding a new builtin for `open`, which we'll use in future tests for the `with` statements (because `open` is my personal first source of `with` statements)

Reviewed By: ngorogiannis

Differential Revision: D49369160

fbshipit-source-id: ee56952ca2fce4fc87033b64631b0e7b6a61474d

infer/src/python/PyBuiltin.ml

@@ -110,7 +110,7 @@ module Builtin = struct
     | CompareOp of Compare.t
   [@@deriving compare]
 
-  type python = Print | Range [@@deriving compare]
+  type python = Print | Range | Open [@@deriving compare]
 
   type t = Primitive of primitive | Textual of textual | Python of python [@@deriving compare]
 end
@@ -122,7 +122,7 @@ type builtin = t = Primitive of primitive | Textual of textual | Python of pytho
 
 let textual t = Textual t
 
-let python_to_string = function Print -> "print" | Range -> "range"
+let python_to_string = function Print -> "print" | Range -> "range" | Open -> "open"
 
 let to_proc_name = function
   | Primitive primitive -> (
@@ -179,7 +179,15 @@ let to_proc_name = function
 
 (** Lookup a [Python] builtin from its name. *)
 let of_string name =
-  match name with "print" -> Some (Python Print) | "range" -> Some (Python Range) | _ -> None
+  match name with
+  | "print" ->
+      Some (Python Print)
+  | "range" ->
+      Some (Python Range)
+  | "open" ->
+      Some (Python Open)
+  | _ ->
+      None
 
 
 let annot typ = T.Typ.{typ; attributes= []}
@@ -330,6 +338,7 @@ module Set = struct
 
   let python_builtins =
     [ (Builtin.Print, {formals_types= None; result_type= annotatedObject; used_struct_types= []})
+    ; (Builtin.Open, {formals_types= None; result_type= annotatedObject; used_struct_types= []})
     ; (Builtin.Range, {formals_types= None; result_type= annotatedObject; used_struct_types= []}) ]
 
 

infer/src/python/unit/PyTransTest.ml

@@ -2866,3 +2866,48 @@ class Test(unittest.TestCase):
 
   no support for `hasattr` at the moment.  Skipping... |}]
   end )
+
+
+let%test_module "with" =
+  ( module struct
+    let%expect_test _ =
+      (* No with for this one it's a baseline to support [open] *)
+      let source = {|
+fp = open("foo.txt", "wt")
+fp.write("yolo")
+          |} in
+      test source ;
+      [%expect
+        {|
+        .source_language = "python"
+
+        define dummy.$toplevel() : *PyNone {
+          #b0:
+              n0 = $builtins.open($builtins.python_string("foo.txt"), $builtins.python_string("wt"))
+              store &dummy::fp <- n0:*PyObject
+              n1:*PyObject = load &dummy::fp
+              n2 = n1.?.write($builtins.python_string("yolo"))
+              ret null
+
+        }
+
+        global dummy::fp: *PyObject
+
+        global $python_implicit_names::__name__: *PyString
+
+        global $python_implicit_names::__file__: *PyString
+
+        declare $builtins.open(...) : *PyObject
+
+        declare $builtins.python_tuple(...) : *PyObject
+
+        declare $builtins.python_bytes(*Bytes) : *PyBytes
+
+        declare $builtins.python_string(*String) : *PyString
+
+        declare $builtins.python_bool(int) : *PyBool
+
+        declare $builtins.python_float(float) : *PyFloat
+
+        declare $builtins.python_int(int) : *PyInt |}]
+  end )