[infer][java] handle int boxing in HashMap model

Summary:
@public
Adds a special case for comparing Integer instances. Makes the tests more
relevant too.

Test Plan: - Added a new test

infer/models/java/src/java/util/HashMap.java

@@ -49,7 +49,7 @@ public abstract class HashMap<K,V> extends AbstractMap<K,V>
     return null;
   }
 
-  public V put(Object key, Object value) {
+  public V put(K key, V value) {
     pushKey(key);
 
     if (InferUndefined.boolean_undefined()) {
@@ -66,7 +66,13 @@ public abstract class HashMap<K,V> extends AbstractMap<K,V>
   }
 
   private boolean _containsKey(Object key) {
-    return lastKey1 == key || lastKey2 == key;
+      return areEqual(key, lastKey1) || areEqual(key, lastKey2);
+  }
+
+  /* does explicit dynamic dispatch to help Infer out */
+  private static boolean areEqual(Object x, Object y) {
+      return x == y
+          || (x instanceof Integer && ((Integer) x).equals(y));
   }
 
 }

infer/src/backend/sil.ml

@@ -441,9 +441,9 @@ module Subtype = struct
           if (should_add) then c:: rest' else rest'
 
   let get_subtypes (c1, (st1, flag1)) (c2, (st2, flag2)) f is_interface =
-    (* (L.d_strln_color Orange ((Mangled.to_string c1)^(subtypes_to_string (st1, flag1))^" <: "^
-    (Mangled.to_string c2)^(subtypes_to_string (st2, flag2))^" ?"^(string_of_bool is_sub)));*)
     let is_sub = f c1 c2 in
+    (* L.d_strln_color Orange ((Mangled.to_string c1)^(subtypes_to_string (st1, flag1))^" <: "^ *)
+    (* (Mangled.to_string c2)^(subtypes_to_string (st2, flag2))^" ?"^(string_of_bool is_sub)); *)
     let pos_st, neg_st = match st1, st2 with
       | Exact, Exact ->
           if (is_sub) then (Some st1, None)

infer/tests/codetoanalyze/java/infer/HashMapExample.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2013- Facebook.
+ * All rights reserved.
+ */
+
+package codetoanalyze.java.infer;
+
+import java.util.HashMap;
+
+public class HashMapExample {
+
+  public static void putIntegerTwiceThenGetTwice(
+    HashMap<Integer, Integer> hashMap
+  ) {
+    Integer i32 = new Integer(32);
+    Integer i52 = new Integer(52);
+
+    hashMap.put(i32, i32);
+    hashMap.put(i52, i52);
+
+    Integer a = hashMap.get(i32);
+    Integer b = hashMap.get(i52);
+
+    a.intValue();
+    b.intValue();
+  }
+
+  public static void containsIntegerTwiceThenGetTwice(
+    HashMap<Integer, Integer> hashMap
+  ) {
+    Integer i32 = new Integer(32);
+    Integer i52 = new Integer(52);
+
+    if (hashMap.containsKey(i32) && hashMap.containsKey(i52)) {
+      Integer a = hashMap.get(i32);
+      Integer b = hashMap.get(i52);
+      a.intValue();
+      b.intValue();
+    }
+  }
+
+  public static int getOneIntegerWithoutCheck() {
+    HashMap<Integer, Integer> hashMap = new HashMap<>();
+    Integer i32 = new Integer(32);
+
+    Integer a = hashMap.get(i32);
+
+    return a.intValue();
+  }
+
+  public static void getTwoIntegersWithOneCheck(
+    Integer i,
+    Integer j
+  ) {
+    HashMap<Integer, Integer> hashMap = new HashMap<>();
+
+    if (hashMap.containsKey(i) && !i.equals(j)) {
+      Integer a = hashMap.get(i);
+      Integer b = hashMap.get(j);
+
+      a.intValue();
+      b.intValue();
+    }
+  }
+
+  public static Integer getOrCreateInteger(
+    final HashMap<Integer, Integer> map,
+    final int id) {
+      Integer x = null;
+      if (map.containsKey(id)) {
+          x = map.get(id);
+      } else {
+          x = new Integer(0);
+          map.put(id, x);
+      }
+      return x;
+  }
+
+  public static void getOrCreateIntegerThenDeref(
+    final HashMap<Integer, Integer> map) {
+      Integer x = getOrCreateInteger(map, 42);
+      // dereference x
+      x.toString();
+  }
+
+}

infer/tests/codetoanalyze/java/infer/HashMapModelTest.java

@@ -1,82 +0,0 @@
-/*
- * Copyright (c) 2013- Facebook.
- * All rights reserved.
- */
-
-package codetoanalyze.java.infer;
-
-import java.util.HashMap;
-
-public class HashMapModelTest {
-
-  public static int putIntegerTwiceThenGetTwice() {
-    HashMap<Integer, Integer> hashMap = new HashMap<>();
-    Integer i32 = new Integer(32);
-    Integer i52 = new Integer(52);
-
-    hashMap.put(i32, i32);
-    hashMap.put(i52, i52);
-
-    Integer a = hashMap.get(i32);
-    Integer b = hashMap.get(i52);
-
-    return a.intValue() * b.intValue();
-  }
-
-  public static int containsIntegerTwiceThenGetTwice(
-    HashMap<Integer, Integer> hashMap
-  ) {
-    Integer i32 = new Integer(32);
-    Integer i52 = new Integer(52);
-
-    if (hashMap.containsKey(i32) && hashMap.containsKey(i52)) {
-      Integer a = hashMap.get(i32);
-      Integer b = hashMap.get(i52);
-      return a.intValue() * b.intValue();
-    }
-
-    return 0;
-  }
-
-  public static int getOneIntegerWithoutCheck(
-    HashMap<Integer, Integer> hashMap
-  ) {
-    Integer i32 = new Integer(32);
-
-    Integer a = hashMap.get(i32);
-
-    return a.intValue();
-  }
-
-  public static int getTwoIntegersWithOneCheck(
-    HashMap<Integer, Integer> hashMap
-  ) {
-    Integer i32 = new Integer(32);
-    Integer i52 = new Integer(52);
-
-    if (hashMap.containsKey(i32)) {
-      Integer a = hashMap.get(i32);
-      Integer b = hashMap.get(i52);
-
-      return a.intValue() * b.intValue();
-    }
-
-    return 0;
-  }
-
-  public static int getTwoParameterIntegersWithOneCheck(
-    HashMap<Integer, Integer> hashMap,
-    Integer i32,
-    Integer i52
-  ) {
-    if (hashMap.containsKey(i32)) {
-      Integer a = hashMap.get(i32);
-      Integer b = hashMap.get(i52);
-
-      return a.intValue() * b.intValue();
-    }
-
-    return 0;
-  }
-
-}

infer/tests/endtoend/java/infer/HashMapModelTest.java

@@ -8,7 +8,6 @@ package endtoend.java.infer;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static utils.matchers.ResultContainsErrorInMethod.contains;
 import static utils.matchers.ResultContainsNoErrorInMethod.doesNotContain;
-import static utils.matchers.ResultContainsOnlyTheseErrors.containsOnly;
 
 import org.junit.BeforeClass;
 import org.junit.Test;
@@ -21,7 +20,7 @@ import utils.InferResults;
 public class HashMapModelTest {
 
   public static final String HashMapModelTest =
-      "infer/tests/codetoanalyze/java/infer/HashMapModelTest.java";
+      "infer/tests/codetoanalyze/java/infer/HashMapExample.java";
 
   public static final String NULL_DEREFERENCE = "NULL_DEREFERENCE";
 
@@ -87,15 +86,28 @@ public class HashMapModelTest {
   }
 
   @Test
-  public void whenInferRunsOnGetTwoParameterIntegersWithOneCheckThenNPEIsFound()
+  public void whenInferRunsOnGetOrCreateIntegerThenNPEIsNotFound()
       throws InterruptedException, IOException, InferException {
     assertThat(
-      "Results should contain null pointer exception error",
+      "Results should not contain null pointer exception error",
       inferResults,
-      contains(
+      doesNotContain(
+        NULL_DEREFERENCE,
+        HashMapModelTest,
+        "getOrCreateInteger")
+    );
+  }
+
+  @Test
+  public void whenInferRunsOnGetOrCreateIntegerThenDerefThenNPEIsNotFound()
+      throws InterruptedException, IOException, InferException {
+    assertThat(
+      "Results should not contain null pointer exception error",
+      inferResults,
+      doesNotContain(
         NULL_DEREFERENCE,
         HashMapModelTest,
-        "getTwoParameterIntegersWithOneCheck")
+        "getOrCreateIntegerThenDeref")
     );
   }