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[nullsafe] Treat parameter in overrides of `equals(Object param)` as nullable.

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Summary:
We already warn about lack of nullable annotations in `equals()`, and even have a specialized error message for that.

But lack of an annotation is not as severe as direct dereference: the
latter is a plain bug which is also a time bomb: it will lead to an NPE not immediately.

This is widespread enough to be reported separately.

Reviewed By: dulmarod

Differential Revision: D19719598

fbshipit-source-id: a535d43ea
master
Mitya Lyubarskiy 5 years ago committed by Facebook Github Bot
parent ae907d80cf
commit 597c730474
6 changed files with 29 additions and 9 deletions
Show Stats Download Patch File Download Diff File

4
infer/src/nullsafe/ErrorRenderingUtils.ml
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@ -22,12 +22,14 @@ let is_object_nullability_self_explanatory ~object_expression (object_origin : T
| NullConst _ ->
(* Expect either a local variable or null literal (latter case is trivial) *)
String.equal object_expression "null"
| MethodParameter {mangled} ->
| MethodParameter (Normal {mangled}) ->
(* Either local variable or literally parameter. In latter case, its nullability is
self-explanatory because the user can quickly see the current method signature.
*)
let param_name = Mangled.to_string mangled in
String.equal object_expression param_name
| MethodParameter ObjectEqualsOverride ->
false
| Field {field_name} ->
(* Either local variable or expression like `<smth>.field_name`. Latter case is trivial:
the user can quickly go to field_name definition and see if its annotation. *)

4
infer/src/nullsafe/eradicate.ml
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@ -41,7 +41,9 @@ module MkCallback (Extension : ExtensionT) : CallBackT = struct
has very special meaning and nullability limitations (it can never be null).
*)
TypeOrigin.This
else TypeOrigin.MethodParameter param_signature
else if PatternMatch.is_override_of_java_lang_object_equals curr_pname then
TypeOrigin.MethodParameter ObjectEqualsOverride
else TypeOrigin.MethodParameter (Normal param_signature)
in
let inferred_nullability = InferredNullability.create origin in
TypeState.add pvar (param_signature.param_annotated_type.typ, inferred_nullability) typestate

17
infer/src/nullsafe/typeOrigin.ml
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@ -13,7 +13,7 @@ type t =
| NullConst of Location.t (** A null literal in the source *)
| NonnullConst of Location.t (** A constant (not equal to null) in the source. *)
| Field of field_origin (** A field access (result of expression `some_object.some_field`) *)
| MethodParameter of AnnotatedSignature.param_signature (** A method's parameter *)
| MethodParameter of method_parameter_origin (** A method's parameter *)
| This (* `this` object. Can not be null, according to Java rules. *)
| MethodCall of method_call_origin (** A result of a method call *)
| CallToGetKnownToContainsKey
@ -34,6 +34,8 @@ type t =
| Undef (** Undefined value before initialization *)
[@@deriving compare]
and method_parameter_origin = Normal of AnnotatedSignature.param_signature | ObjectEqualsOverride
and field_origin =
{ object_origin: t (** field's object origin (object is before field access operator `.`) *)
; field_name: Fieldname.t
@ -70,8 +72,11 @@ let get_nullability = function
Nullability.StrictNonnull
| Field {field_type= {nullability}} ->
AnnotatedNullability.get_nullability nullability
| MethodParameter {param_annotated_type= {nullability}} ->
| MethodParameter (Normal {param_annotated_type= {nullability}}) ->
AnnotatedNullability.get_nullability nullability
| MethodParameter ObjectEqualsOverride ->
(* `Object.equals(obj)` should expect to be called with null `obj` *)
Nullability.Nullable
| MethodCall {annotated_signature= {ret= {ret_annotated_type= {nullability}}}} ->
AnnotatedNullability.get_nullability nullability
@ -83,9 +88,11 @@ let rec to_string = function
"Const (nonnull)"
| Field {object_origin; field_name} ->
"Field " ^ Fieldname.to_string field_name ^ " (object: " ^ to_string object_origin ^ ")"
| MethodParameter {mangled; param_annotated_type= {nullability}} ->
| MethodParameter (Normal {mangled; param_annotated_type= {nullability}}) ->
Format.asprintf "Param %s <%a>" (Mangled.to_string mangled) AnnotatedNullability.pp
nullability
| MethodParameter ObjectEqualsOverride ->
"Param(ObjectEqualsOverride)"
| This ->
"this"
| MethodCall {pname} ->
@ -149,8 +156,10 @@ let get_description origin =
Some ("null constant" ^ atline loc)
| Field {field_name; access_loc} ->
Some ("field " ^ Fieldname.get_field_name field_name ^ atline access_loc)
| MethodParameter {mangled} ->
| MethodParameter (Normal {mangled}) ->
Some ("method parameter " ^ Mangled.to_string mangled)
| MethodParameter ObjectEqualsOverride ->
Some "Object.equals() should be able to accept `null`, according to the Java specification"
| MethodCall {pname; call_loc; annotated_signature} ->
Some (get_method_ret_description pname call_loc annotated_signature)
(* These are origins of non-nullable expressions that are result of evaluating of some rvalue.

4
infer/src/nullsafe/typeOrigin.mli
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@ -11,7 +11,7 @@ type t =
| NullConst of Location.t (** A null literal in the source *)
| NonnullConst of Location.t (** A constant (not equal to null) in the source. *)
| Field of field_origin (** A field access (result of expression `some_object.some_field`) *)
| MethodParameter of AnnotatedSignature.param_signature (** A method's parameter *)
| MethodParameter of method_parameter_origin (** A method's parameter *)
| This (* `this` object. Can not be null, according to Java rules. *)
| MethodCall of method_call_origin (** A result of a method call *)
| CallToGetKnownToContainsKey
@ -32,6 +32,8 @@ type t =
| Undef (** Undefined value before initialization *)
[@@deriving compare]
and method_parameter_origin = Normal of AnnotatedSignature.param_signature | ObjectEqualsOverride
and field_origin =
{ object_origin: t (** field's object origin (object is before field access operator `.`) *)
; field_name: Fieldname.t

8
infer/tests/codetoanalyze/java/nullsafe-default/InconsistentSubclassAnnotation.java
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@ -172,11 +172,15 @@ class ExtendsExternalLibrary extends SomeExternalClass {
}
}
// Check that we have a special error message for this method
// Check that 1) we have a special error message for lack of annotation in this method and 2) treat
// `x` as implicitly nullable
class JavaLangEquals {
@Override
public boolean equals(Object x) {
return false;
// BAD: x can not be directly dereferenced without null comparison:
// it is implicitly nullable because Java requires `x.equals(null)` to work correctly.
// It is a common enough case to make the nullsafe support this specifically.
return x.toString() == "JavaLangEquals";
}
}

1
infer/tests/codetoanalyze/java/nullsafe-default/issues.exp
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@ -73,6 +73,7 @@ codetoanalyze/java/nullsafe-default/InconsistentSubclassAnnotation.java, codetoa
codetoanalyze/java/nullsafe-default/InconsistentSubclassAnnotation.java, codetoanalyze.java.nullsafe_default.ArgNullToValForInterfaceInAnotherFileBAD.implementInAnotherFile(java.lang.String):java.lang.String, 0, ERADICATE_INCONSISTENT_SUBCLASS_PARAMETER_ANNOTATION, no_bucket, WARNING, [First parameter `s` of method `ArgNullToValForInterfaceInAnotherFileBAD.implementInAnotherFile(...)` is missing `@Nullable` declaration when overriding `InconsistentSubclassAnnotationInterface.implementInAnotherFile(...)`. The parent method declared it can handle `null` for this param, so the child should also declare that.]
codetoanalyze/java/nullsafe-default/InconsistentSubclassAnnotation.java, codetoanalyze.java.nullsafe_default.ExtendsExternalLibrary.externalMethod2(java.lang.Object):void, 0, ERADICATE_INCONSISTENT_SUBCLASS_PARAMETER_ANNOTATION, no_bucket, WARNING, [First parameter `object` of method `ExtendsExternalLibrary.externalMethod2(...)` is missing `@Nullable` declaration when overriding `SomeExternalClass.externalMethod2(...)`. The parent method declared it can handle `null` for this param, so the child should also declare that.]
codetoanalyze/java/nullsafe-default/InconsistentSubclassAnnotation.java, codetoanalyze.java.nullsafe_default.JavaLangEquals.equals(java.lang.Object):boolean, 0, ERADICATE_INCONSISTENT_SUBCLASS_PARAMETER_ANNOTATION, no_bucket, WARNING, [Parameter `x` is missing `@Nullable` declaration: according to the Java Specification, for any object `x` call `x.equals(null)` should properly return false.]
codetoanalyze/java/nullsafe-default/InconsistentSubclassAnnotation.java, codetoanalyze.java.nullsafe_default.JavaLangEquals.equals(java.lang.Object):boolean, 0, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [`x` is nullable and is not locally checked for null when calling `toString()`: Object.equals() should be able to accept `null`, according to the Java specification]
codetoanalyze/java/nullsafe-default/InconsistentSubclassAnnotation.java, codetoanalyze.java.nullsafe_default.NullableConcreteGetterBAD.get():java.lang.String, 0, ERADICATE_INCONSISTENT_SUBCLASS_RETURN_ANNOTATION, no_bucket, WARNING, [Child method `NullableConcreteGetterBAD.get()` is not substitution-compatible with its parent: the return type is declared as nullable, but parent method `NonNullableInterfaceGetterOK.get()` is missing `@Nullable` declaration. Either mark the parent as `@Nullable` or ensure the child does not return `null`.]
codetoanalyze/java/nullsafe-default/InconsistentSubclassAnnotation.java, codetoanalyze.java.nullsafe_default.OverloadExistingIncorrectBAD.overload(java.lang.String,java.lang.String):java.lang.String, 0, ERADICATE_INCONSISTENT_SUBCLASS_RETURN_ANNOTATION, no_bucket, WARNING, [Child method `OverloadExistingIncorrectBAD.overload(...)` is not substitution-compatible with its parent: the return type is declared as nullable, but parent method `Overloads.overload(...)` is missing `@Nullable` declaration. Either mark the parent as `@Nullable` or ensure the child does not return `null`.]
codetoanalyze/java/nullsafe-default/InconsistentSubclassAnnotation.java, codetoanalyze.java.nullsafe_default.ReturnValToNullBAD.valBoth(java.lang.String):java.lang.String, 0, ERADICATE_INCONSISTENT_SUBCLASS_RETURN_ANNOTATION, no_bucket, WARNING, [Child method `ReturnValToNullBAD.valBoth(...)` is not substitution-compatible with its parent: the return type is declared as nullable, but parent method `VariousMethods.valBoth(...)` is missing `@Nullable` declaration. Either mark the parent as `@Nullable` or ensure the child does not return `null`.]

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