[eradicate] record false positive when testing the return on an assignment

Reviewed By: ngorogiannis

Differential Revision: D15321693

fbshipit-source-id: a6aa7068a

infer/tests/codetoanalyze/java/eradicate/NullMethodCall.java

@@ -337,14 +337,21 @@ public class NullMethodCall {
   void nullabilityNotPreservedAfterAssignment() {
     if (getNullable() != null) {
       Object t = getNullable();
-      t.toString();
+      t.toString(); // Should not warn here
     }
   }
 
   void nullabilityStoredInBooleanFP() {
     boolean isNotNull = getNullable() != null;
     if (isNotNull) {
-      getNullable().toString();
+      getNullable().toString(); // Should not warn here
+    }
+  }
+
+  void testInAssignmentFP(@Nullable Object object) {
+    Object t;
+    while ((t = getNullable()) != null) {
+      t.toString(); // Should not warn here
     }
   }
 }

infer/tests/codetoanalyze/java/eradicate/issues.exp

@@ -58,6 +58,7 @@ codetoanalyze/java/eradicate/NullMethodCall.java, codetoanalyze.java.eradicate.N
 codetoanalyze/java/eradicate/NullMethodCall.java, codetoanalyze.java.eradicate.NullMethodCall.nullabilityStoredInBooleanFP():void, 3, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `getNullable()` in the call to `toString()` is nullable and is not locally checked for null. (Origin: call to getNullable() at line 345)]
 codetoanalyze/java/eradicate/NullMethodCall.java, codetoanalyze.java.eradicate.NullMethodCall.testExceptionPerInstruction(int):void, 6, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `s` in the call to `length()` is nullable and is not locally checked for null. (Origin: null constant at line 180)]
 codetoanalyze/java/eradicate/NullMethodCall.java, codetoanalyze.java.eradicate.NullMethodCall.testFieldAssignmentIfThenElse(java.lang.String):void, 2, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `s` in the call to `length()` is nullable and is not locally checked for null. (Origin: null constant at line 171)]
+codetoanalyze/java/eradicate/NullMethodCall.java, codetoanalyze.java.eradicate.NullMethodCall.testInAssignmentFP(java.lang.Object):void, 3, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `t` in the call to `toString()` is nullable and is not locally checked for null. (Origin: call to getNullable() at line 353)]
 codetoanalyze/java/eradicate/NullMethodCall.java, codetoanalyze.java.eradicate.NullMethodCall.testMapGetBad(java.util.Map,java.util.HashMap,java.util.concurrent.ConcurrentHashMap):void, 2, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `m.get(...)` in the call to `toString()` is nullable and is not locally checked for null. (Origin: call to get(...) modelled in modelTables.ml at line 259)]
 codetoanalyze/java/eradicate/NullMethodCall.java, codetoanalyze.java.eradicate.NullMethodCall.testMapGetBad(java.util.Map,java.util.HashMap,java.util.concurrent.ConcurrentHashMap):void, 3, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `hm.get(...)` in the call to `toString()` is nullable and is not locally checked for null. (Origin: call to get(...) modelled in modelTables.ml at line 260)]
 codetoanalyze/java/eradicate/NullMethodCall.java, codetoanalyze.java.eradicate.NullMethodCall.testMapGetBad(java.util.Map,java.util.HashMap,java.util.concurrent.ConcurrentHashMap):void, 4, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `chm.get(...)` in the call to `toString()` is nullable and is not locally checked for null. (Origin: call to get(...) modelled in modelTables.ml at line 261)]