[erl-frontend] Add support for guards

Summary: Add support for guards, both in function clauses and case clauses.

Reviewed By: rgrig

Differential Revision: D29634937

fbshipit-source-id: 5a9f8ec2d

infer/src/erlang/ErlangTranslator.ml

@@ -348,6 +348,38 @@ let rec translate_pattern env (value : Ident.t) {Ast.line; simple_expression} :
       Block.make_failure env
 
 
+and translate_guard_expression env (expression : Ast.expression) : Ident.t * Block.t =
+  let id = Ident.create_fresh Ident.knormal in
+  let block = translate_expression {env with result= Present (Exp.Var id)} expression in
+  (* If we'd like to catch "silent" errors later, we might do it here *)
+  (id, block)
+
+
+and translate_guard env (expressions : Ast.expression list) : Block.t =
+  match expressions with
+  | [] ->
+      Block.make_success env
+  | _ ->
+      let ids_blocks = List.map ~f:(translate_guard_expression env) expressions in
+      let ids, expr_blocks = List.unzip ids_blocks in
+      let make_and (e1 : Exp.t) (e2 : Exp.t) = Exp.BinOp (LAnd, e1, e2) in
+      let make_var (id : Ident.t) : Exp.t = Var id in
+      let cond = List.reduce_exn (List.map ids ~f:make_var) ~f:make_and in
+      let start = Node.make_nop env in
+      let exit_success = Node.make_if env true cond in
+      let exit_failure = Node.make_if env false cond in
+      start |~~> [exit_success; exit_failure] ;
+      Block.all env (expr_blocks @ [{Block.start; exit_success; exit_failure}])
+
+
+and translate_guard_sequence env (guards : Ast.expression list list) : Block.t =
+  match guards with
+  | [] ->
+      Block.make_success env
+  | _ ->
+      Block.any env (List.map ~f:(translate_guard env) guards)
+
+
 and translate_expression env {Ast.line; simple_expression} =
   let env = update_location line env in
   let any = ptr_typ_of_name Any in
@@ -504,22 +536,20 @@ and translate_body env body : Block.t =
 
 (** Assumes that the values on which patterns should be matched have been loaded into the
     identifiers listed in [values]. *)
-and translate_case_clause env (values : Ident.t list) {Ast.line= _; patterns; guards= _; body} :
+and translate_case_clause env (values : Ident.t list) {Ast.line= _; patterns; guards; body} :
     Block.t =
-  let matchers_block =
-    let f (one_value, one_pattern) = translate_pattern env one_value one_pattern in
-    let matchers = List.map ~f (List.zip_exn values patterns) in
-    Block.all env matchers
-  in
+  let f (one_value, one_pattern) = translate_pattern env one_value one_pattern in
+  let matchers = List.map ~f (List.zip_exn values patterns) in
+  let guard_block = translate_guard_sequence env guards in
+  let matchers_and_guards = Block.all env [Block.all env matchers; guard_block] in
   let body_block = translate_body env body in
-  (* TODO: Evaluate the guards. *)
-  matchers_block.exit_success |~~> [body_block.start] ;
+  matchers_and_guards.exit_success |~~> [body_block.start] ;
   let () =
     let (Present procdesc) = env.procdesc in
     body_block.exit_failure |~~> [Procdesc.get_exit_node procdesc]
   in
-  { start= matchers_block.start
-  ; exit_failure= matchers_block.exit_failure
+  { start= matchers_and_guards.start
+  ; exit_failure= matchers_and_guards.exit_failure
   ; exit_success= body_block.exit_success }
 
 

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

@@ -2,6 +2,10 @@ codetoanalyze/erlang/nonmatch/src/case_expression.erl, case_simple/1, 1, NONEXHA
 codetoanalyze/erlang/nonmatch/src/case_expression.erl, case_test_simple3_Bad/0, -14, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [calling context starts here,in call to `case_simple/1`,no pattern match here]
 codetoanalyze/erlang/nonmatch/src/case_expression.erl, case_test_tail3_Bad/0, -15, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [calling context starts here,in call to `tail_with_case/1`,no pattern match here]
 codetoanalyze/erlang/nonmatch/src/case_expression.erl, tail_with_case/1, 1, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [*** LATENT ***,no pattern match here]
+codetoanalyze/erlang/nonmatch/src/case_guards.erl, accepts_positive/1, 1, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [*** LATENT ***,no pattern match here]
+codetoanalyze/erlang/nonmatch/src/case_guards.erl, accepts_positive2/1, 1, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [*** LATENT ***,no pattern match here]
+codetoanalyze/erlang/nonmatch/src/case_guards.erl, test_accepts_positive2_Bad/0, -16, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [calling context starts here,in call to `accepts_positive2/1`,no pattern match here]
+codetoanalyze/erlang/nonmatch/src/case_guards.erl, test_accepts_positive_Bad/0, -15, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [calling context starts here,in call to `accepts_positive/1`,no pattern match here]
 codetoanalyze/erlang/nonmatch/src/function.erl, assert_empty/1, 0, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [*** LATENT ***,no pattern match here]
 codetoanalyze/erlang/nonmatch/src/function.erl, assert_second_is_nil/1, 0, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [*** LATENT ***,no pattern match here]
 codetoanalyze/erlang/nonmatch/src/function.erl, fp_list_match_test_secondnil1_Ok/0, -17, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [calling context starts here,in call to `assert_second_is_nil/1`,no pattern match here]
@@ -11,6 +15,13 @@ codetoanalyze/erlang/nonmatch/src/function.erl, list_match_test_empty3_Bad/0, -1
 codetoanalyze/erlang/nonmatch/src/function.erl, list_match_test_secondnil3_Bad/0, -22, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [calling context starts here,in call to `assert_second_is_nil/1`,no pattern match here]
 codetoanalyze/erlang/nonmatch/src/function.erl, list_match_test_tail3_Bad/0, -8, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [calling context starts here,in call to `tail/1`,no pattern match here]
 codetoanalyze/erlang/nonmatch/src/function.erl, tail/1, 0, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [*** LATENT ***,no pattern match here]
+codetoanalyze/erlang/nonmatch/src/function_guards.erl, accepts_positive/1, 0, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [*** LATENT ***,no pattern match here]
+codetoanalyze/erlang/nonmatch/src/function_guards.erl, accepts_positive2/1, 0, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [*** LATENT ***,no pattern match here]
+codetoanalyze/erlang/nonmatch/src/function_guards.erl, fp_accepts_all_tricky3/1, 0, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [*** LATENT ***,no pattern match here]
+codetoanalyze/erlang/nonmatch/src/function_guards.erl, possible_exception/1, 0, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [*** LATENT ***,no pattern match here]
+codetoanalyze/erlang/nonmatch/src/function_guards.erl, test_accepts_positive2_Bad/0, -23, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [calling context starts here,in call to `accepts_positive2/1`,no pattern match here]
+codetoanalyze/erlang/nonmatch/src/function_guards.erl, test_accepts_positive_Bad/0, -19, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [calling context starts here,in call to `accepts_positive/1`,no pattern match here]
+codetoanalyze/erlang/nonmatch/src/function_guards.erl, test_possible_exception_Bad/0, -37, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [calling context starts here,in call to `possible_exception/1`,no pattern match here]
 codetoanalyze/erlang/nonmatch/src/match.erl, fp_match_test_c_Ok/0, 1, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [no pattern match here]
 codetoanalyze/erlang/nonmatch/src/match.erl, fp_match_test_d_Ok/0, -13, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [calling context starts here,in call to `tail/1`,no pattern match here]
 codetoanalyze/erlang/nonmatch/src/match.erl, match_test_b_Bad/0, 1, CONSTANT_ADDRESS_DEREFERENCE, no_bucket, WARNING, [in call to `two/0`,is the constant 2,assigned,returned,return from call to `two/0`,invalid access occurs here]

infer/tests/codetoanalyze/erlang/nonmatch/src/case_guards.erl

@@ -0,0 +1,46 @@
+% 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(case_guards).
+
+-export([
+    test_accepts_positive_Bad/0,
+    test_accepts_positive_Ok/0,
+    test_accepts_positive2_Bad/0,
+    test_accepts_positive2_Ok/0,
+    test_accepts_all_Ok/0
+]).
+
+accepts_positive(X) ->
+    case X of
+        X when X > 0 -> ok
+    end.
+
+accepts_positive2(X) ->
+    case X of
+        X when 1 =:= 1, 1 =:= 0; X > 0 -> ok
+    end.
+
+accepts_all(X) ->
+    case X of
+        X when X > 0 -> ok;
+        X when not (X > 0) -> ok
+    end.
+
+test_accepts_positive_Bad() ->
+    accepts_positive(0).
+
+test_accepts_positive_Ok() ->
+    accepts_positive(1).
+
+test_accepts_positive2_Bad() ->
+    accepts_positive2(0).
+
+test_accepts_positive2_Ok() ->
+    accepts_positive2(1).
+
+test_accepts_all_Ok() ->
+    accepts_all(0),
+    accepts_all(1).

infer/tests/codetoanalyze/erlang/nonmatch/src/function_guards.erl

@@ -0,0 +1,82 @@
+% 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(function_guards).
+
+-export([
+    test_accepts_positive_Bad/0,
+    test_accepts_positive_Ok/0,
+    test_accepts_positive2_Bad/0,
+    test_accepts_positive2_Ok/0,
+    test_accepts_all_basic_Ok/0,
+    test_accepts_all_basic2_Ok/0,
+    test_accepts_all_tricky_Ok/0,
+    test_accepts_all_tricky2_Ok/0,
+    test_accepts_all_tricky3_Ok/0,
+    test_possible_exception_Ok/0,
+    test_possible_exception_Bad/0,
+    fn_test_possible_exception2_Bad/0
+]).
+
+accepts_positive(X) when X > 0 -> ok.
+
+accepts_positive2(X) when 1 =:= 1, 1 =:= 0; X > 0 -> ok.
+
+accepts_all_basic(X) when X > 0 -> ok;
+accepts_all_basic(_) -> ok.
+
+accepts_all_basic2(X) when X > 0; 1 =:= 1 -> ok.
+
+accepts_all_tricky(X) when X > 0; not (X > 0) -> ok.
+
+accepts_all_tricky2(X) when X > 0 -> ok;
+accepts_all_tricky2(X) when not (X > 0) -> ok.
+
+% FP (T95259136)
+fp_accepts_all_tricky3(X) when X > 0; X =< 0 -> ok.
+
+possible_exception(X) when 1 div X =:= 1 -> ok.
+
+test_accepts_positive_Bad() ->
+    accepts_positive(0).
+
+test_accepts_positive_Ok() ->
+    accepts_positive(1).
+
+test_accepts_positive2_Bad() ->
+    accepts_positive2(0).
+
+test_accepts_positive2_Ok() ->
+    accepts_positive2(1).
+
+test_accepts_all_basic_Ok() ->
+    accepts_all_basic(0),
+    accepts_all_basic(1).
+
+test_accepts_all_basic2_Ok() ->
+    accepts_all_basic2(0),
+    accepts_all_basic2(1).
+
+test_accepts_all_tricky_Ok() ->
+    accepts_all_tricky(0),
+    accepts_all_tricky(1).
+
+test_accepts_all_tricky2_Ok() ->
+    accepts_all_tricky2(0),
+    accepts_all_tricky2(1).
+
+test_accepts_all_tricky3_Ok() ->
+    fp_accepts_all_tricky3(0),
+    fp_accepts_all_tricky3(1).
+
+test_possible_exception_Ok() ->
+    possible_exception(1).
+
+test_possible_exception_Bad() ->
+    possible_exception(2).
+
+% FN (T95472386)
+fn_test_possible_exception2_Bad() ->
+    possible_exception(0).