[nullsafe] Introduce a flag for conditionally disabling field not initialized issue

Summary:
Now we can either disable it, or enable it only.
For integrations that disable it, this will allow to enable it for
NullsafeStrict classes without enabled it fully

Reviewed By: artempyanykh

Differential Revision: D19409131

fbshipit-source-id: a2b1fe650

infer/man/man1/infer-full.txt

@@ -1537,6 +1537,12 @@ INTERNAL OPTIONS
        --nullable-annotation-name-reset
            Cancel the effect of --nullable-annotation-name.
 
+       --nullsafe-disable-field-not-initialized-in-nonstrict-classes
+           Activates: Nullsafe: In this mode field not initialized issues
+           won't be reported unless the class is marked as @NullsafeStrict.
+           This feature is needed for compatibility reasons. (Conversely:
+           --no-nullsafe-disable-field-not-initialized-in-nonstrict-classes)
+
        --no-nullsafe-optimistic-third-party-params-in-non-strict
            Deactivates: Nullsafe: in this mode we treat non annotated third
            party method params as if they were annotated as nullable.

infer/src/base/Config.ml

@@ -1742,6 +1742,12 @@ and nullable_annotation =
   CLOpt.mk_string_opt ~long:"nullable-annotation-name" "Specify custom nullable annotation name"
 
 
+and nullsafe_disable_field_not_initialized_in_nonstrict_classes =
+  CLOpt.mk_bool ~long:"nullsafe-disable-field-not-initialized-in-nonstrict-classes" ~default:false
+    "Nullsafe: In this mode field not initialized issues won't be reported unless the class is \
+     marked as @NullsafeStrict. This feature is needed for compatibility reasons."
+
+
 and nullsafe_optimistic_third_party_params_in_non_strict =
   CLOpt.mk_bool
     ~long:
@@ -2981,6 +2987,10 @@ and nelseg = !nelseg
 
 and nullable_annotation = !nullable_annotation
 
+and nullsafe_disable_field_not_initialized_in_nonstrict_classes =
+  !nullsafe_disable_field_not_initialized_in_nonstrict_classes
+
+
 and nullsafe_optimistic_third_party_params_in_non_strict =
   !nullsafe_optimistic_third_party_params_in_non_strict
 

infer/src/base/Config.mli

@@ -484,6 +484,8 @@ val nullable_annotation : string option
 
 val nullsafe : bool
 
+val nullsafe_disable_field_not_initialized_in_nonstrict_classes : bool
+
 val nullsafe_optimistic_third_party_params_in_non_strict : bool
 
 val nullsafe_third_party_signatures : string option

infer/src/nullsafe/eradicateChecks.ml

@@ -297,9 +297,18 @@ let check_constructor_initialization tenv find_canonical_duplicate curr_construc
                 is_field_declared_as_nonnull annotated_field
                 && not is_initialized_in_either_constructor_or_initializer
               then
-                report_error tenv find_canonical_duplicate
-                  (TypeErr.Field_not_initialized {is_strict_mode; field_name})
-                  None loc curr_constructor_pdesc ;
+                if
+                  Config.nullsafe_disable_field_not_initialized_in_nonstrict_classes
+                  && not is_strict_mode
+                then
+                  (* Behavior needed for backward compatibility, where we are not ready to surface this type of errors by default.
+                     Hovewer, this error should be always turned on for @NullsafeStrict classes.
+                  *)
+                  ()
+                else
+                  report_error tenv find_canonical_duplicate
+                    (TypeErr.Field_not_initialized {is_strict_mode; field_name})
+                    None loc curr_constructor_pdesc ;
               (* Check if field is over-annotated. *)
               match annotated_field with
               | None ->