[erl-frontend] Support if expressions

Summary: Add support for `if` expressions.

Reviewed By: rgrig

Differential Revision: D29637230

fbshipit-source-id: 5dee00345

infer/src/erlang/ErlangTranslator.ml

@@ -461,6 +461,12 @@ and translate_expression env {Ast.line; simple_expression} =
           Sil.Call ((ret_var, any), fun_exp, args, env.location, CallFlags.default)
         in
         Block.all env [head_block; tail_block; Block.make_instruction env [call_instruction]]
+    | If clauses ->
+        let blocks = Block.any env (List.map ~f:(translate_case_clause env []) clauses) in
+        let crash_node = Node.make_pattern_fail env in
+        blocks.exit_failure |~~> [crash_node] ;
+        let blocks = {blocks with exit_failure= crash_node} in
+        blocks
     | Literal (Atom atom) ->
         let hash =
           (* With this hack, an atom may accidentaly be considered equal to an unrelated integer.

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

@@ -22,6 +22,8 @@ codetoanalyze/erlang/nonmatch/src/function_guards.erl, possible_exception/1, 0,
 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/if_expression.erl, accepts_positive/1, 1, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [*** LATENT ***,no pattern match here]
+codetoanalyze/erlang/nonmatch/src/if_expression.erl, test_accepts_positive_Bad/0, -13, NONEXHAUSTIVE_PATTERN_MATCH, no_bucket, ERROR, [calling context starts here,in call to `accepts_positive/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/if_expression.erl

@@ -0,0 +1,33 @@
+% 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(if_expression).
+
+-export([
+    test_accepts_positive_Ok/0,
+    test_accepts_positive_Bad/0,
+    test_accepts_all_Ok/0
+]).
+
+accepts_positive(X) ->
+    if
+        X > 0 -> ok
+    end.
+
+accepts_all(X) ->
+    if
+        X > 0 -> ok;
+        not (X > 0) -> ok
+    end.
+
+test_accepts_positive_Ok() ->
+    accepts_positive(1).
+
+test_accepts_positive_Bad() ->
+    accepts_positive(0).
+
+test_accepts_all_Ok() ->
+    accepts_all(0),
+    accepts_all(1).