[erl-frontend] Parse strict bitstring generators

Summary: We don't support them during translation, but at least parse them.

Reviewed By: rgrig

Differential Revision: D91224325

fbshipit-source-id: 6eab1e2d1b022503201b07db8edd3b42ca466152

Author: hajduakos

infer/src/erlang/ErlangAst.ml

@@ -111,7 +111,7 @@ and simple_expression =
 and expression = {location: location; simple_expression: simple_expression}
 
 and qualifier =
-  | BitsGenerator of {pattern: expression; expression: expression}
+  | BitsGenerator of {pattern: expression; expression: expression; strict: bool}
   | Filter of expression
   | Generator of {pattern: expression; expression: expression; strict: bool}
   | MapGenerator of {pattern: association; expression: expression; strict: bool}

infer/src/erlang/ErlangJsonParser.ml

@@ -508,7 +508,11 @@ and to_qualifier gen_uniq json : Ast.qualifier option =
   | `List [`String "b_generate"; _anno; pattern; expression] ->
       let* pattern = to_expression gen_uniq pattern in
       let* expression = to_expression gen_uniq expression in
-      Some (Ast.BitsGenerator {pattern; expression})
+      Some (Ast.BitsGenerator {pattern; expression; strict= false})
+  | `List [`String "b_generate_strict"; _anno; pattern; expression] ->
+      let* pattern = to_expression gen_uniq pattern in
+      let* expression = to_expression gen_uniq expression in
+      Some (Ast.BitsGenerator {pattern; expression; strict= true})
   | `List [`String "generate"; _anno; pattern; expression] ->
       let* pattern = to_expression gen_uniq pattern in
       let* expression = to_expression gen_uniq expression in

infer/tests/codetoanalyze/erlang/compiler/issues.exp

@@ -70,6 +70,10 @@ features_arithmetic:test_uminus1_Ok/0: ok
 features_arithmetic:test_uminus2_Bad/0: expected_crash
 features_arithmetic:test_uminus2_Ok/0: ok
 
+----- features_bc -----
+features_bc:fn_test_strict_Bad/0: bad_generator
+features_bc:test_strict_Ok/0: ok
+
 ----- features_binary_attr -----
 features_binary_attr:test_bad_Bad/0: expected_crash
 features_binary_attr:test_ok_Ok/0: ok

infer/tests/codetoanalyze/erlang/pulse/features/features_bc.erl

@@ -0,0 +1,18 @@
+% Copyright (c) Facebook, Inc. and its affiliates.
+%
+% This source code is licensed under the MIT license found in the
+% LICENSE file in the root directory of this source tree.
+
+-module(features_bc).
+
+-export([
+    test_strict_Ok/0,
+    fn_test_strict_Bad/0
+]).
+
+test_strict_Ok() ->
+    [X || <<X>> <:= <<1>>].
+
+% We don't support bitstring generators
+fn_test_strict_Bad() ->
+    [X || <<X>> <:= nope].