[nullsafe][annotation graph] Support `Object.equals()`

Summary:
There is a feature in Nullsafe that is interfering with "annotation
graph" feature. Because of this we would not detect provisional
violations for misuses of params of equals() (They will be recorded
as user facing rather than provisional issues).

This diff turns this feature off for annotation graph mode.

Reviewed By: artempyanykh

Differential Revision: D24726655

fbshipit-source-id: 4b7577667

infer/src/nullsafe/eradicate.ml

@@ -25,8 +25,19 @@ let callback1 ({IntraproceduralAnalysis.proc_desc= curr_pdesc; _} as analysis_da
            has very special meaning and nullability limitations (it can never be null).
         *)
         TypeOrigin.This
-      else if PatternMatch.Java.is_override_of_lang_object_equals curr_pname then
+        (* An extra feature of Nullsafe. If the method overrides `Object.equals()`, but does not specify @Nullable annotation for the param,
-        TypeOrigin.CurrMethodParameter ObjectEqualsOverride
+           a normal "inconsistent subclass parameter annotation" will be issued.
+           But apart from this we want to issue additional violations every time the value is used as a non-nullable.
+           This is to distinct "benign" cases where the value is simply not annotated from real bugs where e.g. the value is actually dereferenced.
+           We achieve this via having a special TypeOrigin for this param, which will be considered as nullable in relevant places.
+        *)
+      else if
+        PatternMatch.Java.is_override_of_lang_object_equals curr_pname
+        && (* Turn this feature off for annotation graph mode. In this mode not annotated, but potentially nullable params
+              are treated in special way, and this conflicts with the trick that is being made here.
+           *)
+        not Config.nullsafe_annotation_graph
+      then TypeOrigin.CurrMethodParameter ObjectEqualsOverride
       else TypeOrigin.CurrMethodParameter (Normal param_signature)
     in
     let inferred_nullability = InferredNullability.create origin in

infer/tests/codetoanalyze/java/nullsafe-annotation-graph/AnnotationGraph.java

@@ -72,6 +72,12 @@ public class AnnotationGraph {
 
     methodC().toString(); // violation for methodC
   }
+
+  @Override
+  public boolean equals(Object obj) {
+    // violation for obj
+    return toString() == obj.toString();
+  }
 }
 
 class SomeExternalClass {

infer/tests/codetoanalyze/java/nullsafe-annotation-graph/issues.exp

@@ -19,20 +19,20 @@ AnnotationGraph:
     kind: Field
     field_name: fieldD
     num_violations: 1
-    dependent_point_ids: [m3]
+    dependent_point_ids: [m4]
     
   Annotation point:
-    id: m3
+    id: m4
     kind: Method
     method_info:
       method_name: methodA
       params: java.lang.String, boolean
       access_level: Private
     num_violations: 0
-    dependent_point_ids: [m5]
+    dependent_point_ids: [m6]
     
   Annotation point:
-    id: m5
+    id: m6
     kind: Method
     method_info:
       method_name: methodB
@@ -42,7 +42,7 @@ AnnotationGraph:
     dependent_point_ids: []
     
   Annotation point:
-    id: m6
+    id: m7
     kind: Method
     method_info:
       method_name: methodC
@@ -52,7 +52,18 @@ AnnotationGraph:
     dependent_point_ids: []
     
   Annotation point:
-    id: p4
+    id: p3
+    kind: Param
+    method_info:
+      method_name: equals
+      params: java.lang.Object
+      access_level: Public
+    param_num: 0
+    num_violations: 1
+    dependent_point_ids: []
+    
+  Annotation point:
+    id: p5
     kind: Param
     method_info:
       method_name: methodA
@@ -60,11 +71,11 @@ AnnotationGraph:
       access_level: Private
     param_num: 0
     num_violations: 0
-    dependent_point_ids: [f0, m3]
+    dependent_point_ids: [f0, m4]
     
   
-codetoanalyze/java/nullsafe-annotation-graph/AnnotationGraph.java, Linters_dummy_method, 12, ERADICATE_META_CLASS_NEEDS_IMPROVEMENT, no_bucket, INFO, [], AnnotationGraph, codetoanalyze.java.nullsafe_annotation_graph, issues: 3, curr_mode: "Default"
+codetoanalyze/java/nullsafe-annotation-graph/AnnotationGraph.java, Linters_dummy_method, 12, ERADICATE_META_CLASS_NEEDS_IMPROVEMENT, no_bucket, INFO, [], AnnotationGraph, codetoanalyze.java.nullsafe_annotation_graph, issues: 4, curr_mode: "Default"
-codetoanalyze/java/nullsafe-annotation-graph/AnnotationGraph.java, Linters_dummy_method, 77, ERADICATE_ANNOTATION_GRAPH, no_bucket, INFO, [], SomeExternalClass, codetoanalyze.java.nullsafe_annotation_graph
+codetoanalyze/java/nullsafe-annotation-graph/AnnotationGraph.java, Linters_dummy_method, 83, ERADICATE_ANNOTATION_GRAPH, no_bucket, INFO, [], SomeExternalClass, codetoanalyze.java.nullsafe_annotation_graph
 AnnotationGraph:
   Annotation point:
     id: p0
@@ -78,7 +89,8 @@ AnnotationGraph:
     dependent_point_ids: []
     
   
-codetoanalyze/java/nullsafe-annotation-graph/AnnotationGraph.java, Linters_dummy_method, 77, ERADICATE_META_CLASS_CAN_BE_NULLSAFE, no_bucket, ADVICE, [Congrats! `SomeExternalClass` is free of nullability issues. Mark it `@Nullsafe(Nullsafe.Mode.LOCAL)` to prevent regressions.], SomeExternalClass, codetoanalyze.java.nullsafe_annotation_graph, issues: 0, curr_mode: "Default", promote_mode: "Strict"
+codetoanalyze/java/nullsafe-annotation-graph/AnnotationGraph.java, Linters_dummy_method, 83, ERADICATE_META_CLASS_CAN_BE_NULLSAFE, no_bucket, ADVICE, [Congrats! `SomeExternalClass` is free of nullability issues. Mark it `@Nullsafe(Nullsafe.Mode.LOCAL)` to prevent regressions.], SomeExternalClass, codetoanalyze.java.nullsafe_annotation_graph, issues: 0, curr_mode: "Default", promote_mode: "Strict"
 codetoanalyze/java/nullsafe-annotation-graph/AnnotationGraph.java, codetoanalyze.java.nullsafe_annotation_graph.AnnotationGraph.<init>(), 0, ERADICATE_FIELD_NOT_INITIALIZED, no_bucket, WARNING, [Field `fieldD` is declared non-nullable, so it should be initialized in the constructor or in an `@Initializer` method], AnnotationGraph, codetoanalyze.java.nullsafe_annotation_graph
 codetoanalyze/java/nullsafe-annotation-graph/AnnotationGraph.java, codetoanalyze.java.nullsafe_annotation_graph.AnnotationGraph.<init>(), 0, ERADICATE_FIELD_NOT_INITIALIZED, no_bucket, WARNING, [Field `fieldB` is declared non-nullable, so it should be initialized in the constructor or in an `@Initializer` method], AnnotationGraph, codetoanalyze.java.nullsafe_annotation_graph
 codetoanalyze/java/nullsafe-annotation-graph/AnnotationGraph.java, codetoanalyze.java.nullsafe_annotation_graph.AnnotationGraph.<init>(), 0, ERADICATE_FIELD_NOT_INITIALIZED, no_bucket, WARNING, [Field `fieldA` is declared non-nullable, so it should be initialized in the constructor or in an `@Initializer` method], AnnotationGraph, codetoanalyze.java.nullsafe_annotation_graph
+codetoanalyze/java/nullsafe-annotation-graph/AnnotationGraph.java, codetoanalyze.java.nullsafe_annotation_graph.AnnotationGraph.equals(java.lang.Object):boolean, 0, ERADICATE_INCONSISTENT_SUBCLASS_PARAMETER_ANNOTATION, no_bucket, WARNING, [Parameter `obj` is missing `@Nullable` declaration: according to the Java Specification, for any object `x` call `x.equals(null)` should properly return false.], AnnotationGraph, codetoanalyze.java.nullsafe_annotation_graph