[clang frontend] Add support for the clang attribute NS_NOESCAPE for Objective-C blocks in Sil

Summary:
This attribute is given to parameters of methods that take Objective-C blocks to show that they will be used only in the current context and won't "escape" the context.
We translate it here, with the goal to use it in a new check later. The check is about not using weakSelf in non-escaping blocks, because retain cycles are not possible.

The translation is a bit complex because the annotation comes in the parameter of a method, but in the checker we will need it in the block. So we pass it around in the frontend from the translation of the method call to the translation context and on to the block expression and the block declaration afterwards.

Reviewed By: ngorogiannis

Differential Revision: D19600377

fbshipit-source-id: dd49539bd

infer/src/IR/ProcAttributes.ml

@@ -49,6 +49,8 @@ type t =
   ; is_defined: bool  (** true if the procedure is defined, and not just declared *)
   ; is_cpp_noexcept_method: bool  (** the procedure is an C++ method annotated with "noexcept" *)
   ; is_java_synchronized_method: bool  (** the procedure is a Java synchronized method *)
+  ; is_no_escape_block: bool
+        (** The procedure is an Objective-C block that has the NS_NOESCAPE attribute *)
   ; is_no_return: bool  (** the procedure is known not to return *)
   ; is_specialized: bool  (** the procedure is a clone specialized for dynamic dispatch handling *)
   ; is_synthetic_method: bool  (** the procedure is a synthetic method *)
@@ -76,6 +78,7 @@ let default translation_unit proc_name =
   ; is_cpp_noexcept_method= false
   ; is_defined= false
   ; is_java_synchronized_method= false
+  ; is_no_escape_block= false
   ; is_no_return= false
   ; is_specialized= false
   ; is_synthetic_method= false
@@ -108,6 +111,7 @@ let pp f
      ; is_defined
      ; is_cpp_noexcept_method
      ; is_java_synchronized_method
+     ; is_no_escape_block
      ; is_no_return
      ; is_specialized
      ; is_synthetic_method
@@ -150,6 +154,7 @@ let pp f
   pp_bool_default ~default:default.is_defined "is_defined" is_defined f () ;
   pp_bool_default ~default:default.is_java_synchronized_method "is_java_synchronized_method"
     is_java_synchronized_method f () ;
+  pp_bool_default ~default:default.is_no_escape_block "is_no_escape_block" is_no_escape_block f () ;
   pp_bool_default ~default:default.is_no_return "is_no_return" is_no_return f () ;
   pp_bool_default ~default:default.is_specialized "is_specialized" is_specialized f () ;
   pp_bool_default ~default:default.is_synthetic_method "is_synthetic_method" is_synthetic_method f

infer/src/IR/ProcAttributes.mli

@@ -33,6 +33,9 @@ type t =
   ; is_defined: bool  (** true if the procedure is defined, and not just declared *)
   ; is_cpp_noexcept_method: bool  (** the procedure is an C++ method annotated with "noexcept" *)
   ; is_java_synchronized_method: bool  (** the procedure is a Java synchronized method *)
+  ; is_no_escape_block: bool
+        (** The procedure is an Objective-C block that is passed to a method in a position annotated
+            with NS_NOESCAPE *)
   ; is_no_return: bool  (** the procedure is known not to return *)
   ; is_specialized: bool  (** the procedure is a clone specialized for dynamic dispatch handling *)
   ; is_synthetic_method: bool  (** the procedure is a synthetic method *)

infer/src/clang/CType_decl.ml

@@ -96,8 +96,10 @@ module BuildMethodSignature = struct
             |> qual_type_to_sil_type tenv
           in
           let is_pointer_to_const = CType.is_pointer_to_const qt in
+          let is_no_escape_block_arg = CAst_utils.is_no_escape_block_arg par in
           let annot = CAst_utils.sil_annot_of_type qt in
           CMethodSignature.mk_param_type name typ ~is_pointer_to_const ~annot
+            ~is_no_escape_block_arg
       | _ ->
           raise CFrontend_errors.Invalid_declaration
     in
@@ -153,7 +155,8 @@ module BuildMethodSignature = struct
     else (return_typ, None, return_typ_annot, false)
 
 
-  let method_signature_of_decl qual_type_to_sil_type tenv method_decl ?block_return_type procname =
+  let method_signature_of_decl qual_type_to_sil_type tenv method_decl ?block_return_type
+      ?(is_no_escape_block = false) procname =
     let decl_info = Clang_ast_proj.get_decl_tuple method_decl in
     let loc = decl_info.Clang_ast_t.di_source_range in
     let ret_type, return_param_typ, ret_typ_annot, has_added_return_param =
@@ -181,6 +184,7 @@ module BuildMethodSignature = struct
     ; method_kind
     ; is_cpp_virtual
     ; is_cpp_nothrow
+    ; is_no_escape_block
     ; is_no_return
     ; is_variadic
     ; pointer_to_parent
@@ -189,11 +193,12 @@ module BuildMethodSignature = struct
 
 
   let method_signature_body_of_decl qual_type_to_sil_type tenv method_decl ?block_return_type
-      procname =
+      ?is_no_escape_block procname =
     let body = CMethodProperties.get_method_body method_decl in
     let init_list_instrs = CMethodProperties.get_init_list_instrs method_decl in
     let ms =
-      method_signature_of_decl qual_type_to_sil_type tenv method_decl ?block_return_type procname
+      method_signature_of_decl qual_type_to_sil_type tenv method_decl ?block_return_type
+        ?is_no_escape_block procname
     in
     (ms, body, init_list_instrs)
 end

infer/src/clang/CType_decl.mli

@@ -53,6 +53,7 @@ val method_signature_of_decl :
      Tenv.t
   -> Clang_ast_t.decl
   -> ?block_return_type:Clang_ast_t.qual_type
+  -> ?is_no_escape_block:bool
   -> Procname.t
   -> CMethodSignature.t
 
@@ -60,6 +61,7 @@ val method_signature_body_of_decl :
      Tenv.t
   -> Clang_ast_t.decl
   -> ?block_return_type:Clang_ast_t.qual_type
+  -> ?is_no_escape_block:bool
   -> Procname.t
   -> CMethodSignature.t
      * Clang_ast_t.stmt option

infer/src/clang/cAst_utils.ml

@@ -555,6 +555,13 @@ let has_block_attribute decl =
       false
 
 
+(* true if a decl has a NS_NOESCAPE attribute *)
+let is_no_escape_block_arg decl =
+  let has_noescape_attr attr = match attr with `NoEscapeAttr _ -> true | _ -> false in
+  let attrs = (Clang_ast_proj.get_decl_tuple decl).di_attributes in
+  List.exists attrs ~f:has_noescape_attr
+
+
 let is_implicit_decl decl =
   let decl_info = Clang_ast_proj.get_decl_tuple decl in
   decl_info.Clang_ast_t.di_is_implicit

infer/src/clang/cAst_utils.mli

@@ -138,6 +138,8 @@ val get_cxx_virtual_base_classes : Clang_ast_t.decl -> Clang_ast_t.type_ptr list
 
 val is_std_vector : Clang_ast_t.qual_type -> bool
 
+val is_no_escape_block_arg : Clang_ast_t.decl -> bool
+
 val has_block_attribute : Clang_ast_t.decl -> bool
 
 val is_implicit_decl : Clang_ast_t.decl -> bool

infer/src/clang/cFrontend_decl.ml

@@ -75,15 +75,16 @@ module CFrontend_decl_funct (T : CModule_type.CTranslation) : CModule_type.CFron
         | None ->
             ([], None)
       in
-      let procname, block_return_type =
+      let is_no_escape_block, procname, block_return_type =
         match block_data_opt with
-        | Some {CModule_type.procname; return_type} ->
-            (procname, Some return_type)
+        | Some {CModule_type.is_no_escape_block_arg; procname; return_type} ->
+            (is_no_escape_block_arg, procname, Some return_type)
         | _ ->
-            (CType_decl.CProcname.from_decl ~tenv func_decl, None)
+            (false, CType_decl.CProcname.from_decl ~tenv func_decl, None)
       in
       let ms, body_opt, extra_instrs =
-        CType_decl.method_signature_body_of_decl tenv func_decl ?block_return_type procname
+        CType_decl.method_signature_body_of_decl tenv func_decl ?block_return_type
+          ~is_no_escape_block procname
       in
       match body_opt with
       | Some body ->

infer/src/clang/cMethodSignature.ml

@@ -12,10 +12,16 @@ open! IStd
 
 module F = Format
 
-type param_type = {name: Mangled.t; typ: Typ.t; is_pointer_to_const: bool; annot: Annot.Item.t}
+type param_type =
+  { annot: Annot.Item.t
+  ; is_no_escape_block_arg: bool
+  ; is_pointer_to_const: bool
+  ; name: Mangled.t
+  ; typ: Typ.t }
 
-let mk_param_type ?(is_pointer_to_const = false) ?(annot = Annot.Item.empty) name typ =
-  {name; typ; is_pointer_to_const; annot}
+let mk_param_type ?(is_pointer_to_const = false) ?(annot = Annot.Item.empty)
+    ?(is_no_escape_block_arg = false) name typ =
+  {name; typ; is_pointer_to_const; annot; is_no_escape_block_arg}
 
 
 type t =
@@ -30,6 +36,7 @@ type t =
   ; method_kind: ClangMethodKind.t
   ; is_cpp_virtual: bool
   ; is_cpp_nothrow: bool
+  ; is_no_escape_block: bool
   ; is_no_return: bool
   ; is_variadic: bool
   ; pointer_to_parent: Clang_ast_t.pointer option
@@ -50,8 +57,9 @@ let is_setter {pointer_to_property_opt; params} =
 
 
 let mk name class_param params ret_type ?(has_added_return_param = false) attributes loc method_kind
-    ?(is_cpp_virtual = false) ?(is_cpp_nothrow = false) ?(is_no_return = false)
-    ?(is_variadic = false) pointer_to_parent pointer_to_property_opt return_param_typ access =
+    ?(is_cpp_virtual = false) ?(is_cpp_nothrow = false) ?(is_no_escape_block = false)
+    ?(is_no_return = false) ?(is_variadic = false) pointer_to_parent pointer_to_property_opt
+    return_param_typ access =
   { name
   ; access
   ; class_param
@@ -63,6 +71,7 @@ let mk name class_param params ret_type ?(has_added_return_param = false) attrib
   ; method_kind
   ; is_cpp_virtual
   ; is_cpp_nothrow
+  ; is_no_escape_block
   ; is_no_return
   ; is_variadic
   ; pointer_to_parent
@@ -71,9 +80,12 @@ let mk name class_param params ret_type ?(has_added_return_param = false) attrib
 
 
 let pp fmt ms =
-  let pp_param fmt {name; typ} = F.fprintf fmt "%a, %a" Mangled.pp name (Typ.pp Pp.text) typ in
-  Format.fprintf fmt "Method %a [%a]->%a %a"
+  let pp_param fmt {name; typ; is_no_escape_block_arg} =
+    F.fprintf fmt "%a, %a (is_no_escape_block=%b)" Mangled.pp name (Typ.pp Pp.text) typ
+      is_no_escape_block_arg
+  in
+  Format.fprintf fmt "Method %a [%a]->%a %a(is_no_escape_block=%b)"
     (Pp.of_string ~f:Procname.to_string)
     ms.name (Pp.comma_seq pp_param) ms.params (Typ.pp Pp.text) (fst ms.ret_type)
     (Pp.of_string ~f:Clang_ast_j.string_of_source_range)
-    ms.loc
+    ms.loc ms.is_no_escape_block

infer/src/clang/cMethodSignature.mli

@@ -10,7 +10,12 @@ open! IStd
 (** Define the signature of a method consisting of its name, its arguments, return type, location
     and whether its an instance method. *)
 
-type param_type = {name: Mangled.t; typ: Typ.t; is_pointer_to_const: bool; annot: Annot.Item.t}
+type param_type =
+  { annot: Annot.Item.t
+  ; is_no_escape_block_arg: bool
+  ; is_pointer_to_const: bool
+  ; name: Mangled.t
+  ; typ: Typ.t }
 
 type t =
   { name: Procname.t
@@ -24,6 +29,7 @@ type t =
   ; method_kind: ClangMethodKind.t
   ; is_cpp_virtual: bool
   ; is_cpp_nothrow: bool
+  ; is_no_escape_block: bool
   ; is_no_return: bool
   ; is_variadic: bool
   ; pointer_to_parent: Clang_ast_t.pointer option
@@ -46,6 +52,7 @@ val mk :
   -> ClangMethodKind.t
   -> ?is_cpp_virtual:bool
   -> ?is_cpp_nothrow:bool
+  -> ?is_no_escape_block:bool
   -> ?is_no_return:bool
   -> ?is_variadic:bool
   -> Clang_ast_t.pointer option
@@ -57,4 +64,9 @@ val mk :
 val pp : Format.formatter -> t -> unit
 
 val mk_param_type :
-  ?is_pointer_to_const:bool -> ?annot:Annot.Item.t -> Mangled.t -> Typ.t -> param_type
+     ?is_pointer_to_const:bool
+  -> ?annot:Annot.Item.t
+  -> ?is_no_escape_block_arg:bool
+  -> Mangled.t
+  -> Typ.t
+  -> param_type

infer/src/clang/cMethod_trans.ml

@@ -112,14 +112,13 @@ let get_class_name_method_call_from_receiver_kind context obj_c_message_expr_inf
 
 let get_objc_method_data obj_c_message_expr_info =
   let selector = obj_c_message_expr_info.Clang_ast_t.omei_selector in
-  let pointer = obj_c_message_expr_info.Clang_ast_t.omei_decl_pointer in
   match obj_c_message_expr_info.Clang_ast_t.omei_receiver_kind with
   | `Instance ->
-      (selector, pointer, MCVirtual)
+      (selector, MCVirtual)
   | `SuperInstance ->
-      (selector, pointer, MCNoVirtual)
+      (selector, MCNoVirtual)
   | `Class _ | `SuperClass ->
-      (selector, pointer, MCStatic)
+      (selector, MCStatic)
 
 
 let should_create_procdesc cfg procname ~defined ~set_objc_accessor_attr =
@@ -248,6 +247,7 @@ let create_local_procdesc ?(set_objc_accessor_attr = false) trans_unit_ctx cfg t
         ; is_defined= defined
         ; is_cpp_noexcept_method= is_cpp_nothrow
         ; is_biabduction_model= Config.biabduction_models_mode
+        ; is_no_escape_block= ms.CMethodSignature.is_no_escape_block
         ; is_no_return= ms.CMethodSignature.is_no_return
         ; is_variadic= ms.CMethodSignature.is_variadic
         ; sentinel_attr= find_sentinel_attribute ms.CMethodSignature.attributes

infer/src/clang/cMethod_trans.mli

@@ -42,8 +42,7 @@ val create_external_procdesc :
   -> (Typ.t * Typ.t list) option
   -> unit
 
-val get_objc_method_data :
-  Clang_ast_t.obj_c_message_expr_info -> string * Clang_ast_t.pointer option * method_call_type
+val get_objc_method_data : Clang_ast_t.obj_c_message_expr_info -> string * method_call_type
 
 val get_class_name_method_call_from_receiver_kind :
   CContext.t -> Clang_ast_t.obj_c_message_expr_info -> (Exp.t * Typ.t) list -> Typ.Name.t

infer/src/clang/cModule_type.ml

@@ -10,6 +10,7 @@ open! IStd
 type block_data =
   { captured_vars: (Pvar.t * Typ.t) list
   ; context: CContext.t
+  ; is_no_escape_block_arg: bool
   ; procname: Procname.t
   ; return_type: Clang_ast_t.qual_type }
 

infer/src/clang/cTrans.ml

@@ -22,25 +22,16 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
      1. method is a predefined model
      2. method is found by clang's resolution
      3. Method is found by our resolution *)
-  let get_callee_objc_method context obj_c_message_expr_info act_params =
+  let get_callee_objc_method context obj_c_message_expr_info callee_ms_opt act_params =
     let open CContext in
-    let selector, method_pointer_opt, mc_type =
-      CMethod_trans.get_objc_method_data obj_c_message_expr_info
-    in
+    let selector, mc_type = CMethod_trans.get_objc_method_data obj_c_message_expr_info in
     let is_instance = mc_type <> CMethod_trans.MCStatic in
     let objc_method_kind = Procname.ObjC_Cpp.objc_method_kind_of_bool is_instance in
     let method_kind =
       if is_instance then ClangMethodKind.OBJC_INSTANCE else ClangMethodKind.OBJC_CLASS
     in
-    let ms_opt =
-      match method_pointer_opt with
-      | Some pointer ->
-          CMethod_trans.method_signature_of_pointer context.tenv pointer
-      | None ->
-          None
-    in
     let proc_name =
-      match CMethod_trans.get_method_name_from_clang context.tenv ms_opt with
+      match CMethod_trans.get_method_name_from_clang context.tenv callee_ms_opt with
       | Some name ->
           name
       | None ->
@@ -61,7 +52,7 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
       | _ ->
           None
     in
-    match (predefined_ms_opt, ms_opt) with
+    match (predefined_ms_opt, callee_ms_opt) with
     | Some ms, _ ->
         ignore
           (CMethod_trans.create_local_procdesc context.translation_unit_context context.cfg
@@ -1254,13 +1245,35 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
     else None
 
 
+  and exec_instruction_with_trans_state trans_state_param callee_ms_opt i stmt =
+    let trans_state_param' =
+      match callee_ms_opt with
+      | Some callee_ms when not trans_state_param.is_fst_arg_objc_instance_method_call ->
+          let ms_param_type_i =
+            let find_arg j _ = Int.equal i j in
+            List.findi ~f:find_arg callee_ms.CMethodSignature.params
+          in
+          let is_no_escape_block_arg =
+            match ms_param_type_i with
+            | Some (_, {CMethodSignature.is_no_escape_block_arg}) ->
+                is_no_escape_block_arg
+            | None ->
+                false
+          in
+          {trans_state_param with is_no_escape_block_arg}
+      | _ ->
+          trans_state_param
+    in
+    exec_with_glvalue_as_reference instruction trans_state_param' stmt
+
+
   (** If the first argument of the call is self in a static context, remove it as an argument and
      change the call from instance to static *)
-  and objCMessageExpr_deal_with_static_self trans_state_param stmt_list obj_c_message_expr_info =
-    match stmt_list with
+  and objCMessageExpr_translate_args trans_state_param args obj_c_message_expr_info callee_ms_opt =
+    match args with
     | stmt :: rest -> (
         let param_trans_results =
-          List.map ~f:(exec_with_glvalue_as_reference instruction trans_state_param) rest
+          List.mapi ~f:(exec_instruction_with_trans_state trans_state_param callee_ms_opt) rest
         in
         try
           let trans_state_param' =
@@ -1268,7 +1281,9 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
               {trans_state_param with is_fst_arg_objc_instance_method_call= true}
             else {trans_state_param with is_fst_arg_objc_instance_method_call= false}
           in
-          let fst_res_trans = instruction trans_state_param' stmt in
+          let fst_res_trans =
+            exec_instruction_with_trans_state trans_state_param' callee_ms_opt 0 stmt
+          in
           (obj_c_message_expr_info, fst_res_trans :: param_trans_results)
         with Self.SelfClassException e ->
           let pointer = obj_c_message_expr_info.Clang_ast_t.omei_decl_pointer in
@@ -1290,9 +1305,17 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
     let method_type_no_ref = CType_decl.get_type_from_expr_info expr_info context.CContext.tenv in
     let method_type = add_reference_if_glvalue method_type_no_ref expr_info in
     let trans_state_pri = PriorityNode.try_claim_priority_node trans_state si in
+    let callee_ms_opt =
+      match obj_c_message_expr_info.Clang_ast_t.omei_decl_pointer with
+      | Some pointer ->
+          CMethod_trans.method_signature_of_pointer context.tenv pointer
+      | None ->
+          None
+    in
     let trans_state_param = {trans_state_pri with succ_nodes= []; var_exp_typ= None} in
     let obj_c_message_expr_info, res_trans_subexpr_list =
-      objCMessageExpr_deal_with_static_self trans_state_param stmt_list obj_c_message_expr_info
+      objCMessageExpr_translate_args trans_state_param stmt_list obj_c_message_expr_info
+        callee_ms_opt
     in
     let subexpr_exprs = collect_returns res_trans_subexpr_list in
     match
@@ -1304,7 +1327,7 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
     | None ->
         let procname = Procdesc.get_proc_name context.CContext.procdesc in
         let callee_name, method_call_type =
-          get_callee_objc_method context obj_c_message_expr_info subexpr_exprs
+          get_callee_objc_method context obj_c_message_expr_info callee_ms_opt subexpr_exprs
         in
         let res_trans_add_self =
           Self.add_self_parameter_for_super_instance si context procname sil_loc
@@ -2785,8 +2808,11 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
           CVar_decl.captured_vars_from_block_info context stmt_info.Clang_ast_t.si_source_range
             block_decl_info.Clang_ast_t.bdi_captured_variables
         in
+        let is_no_escape_block_arg = trans_state.is_no_escape_block_arg in
         let res = closure_trans procname captured_vars context stmt_info expr_info in
-        let block_data = Some {CModule_type.captured_vars; context; procname; return_type} in
+        let block_data =
+          Some {CModule_type.captured_vars; context; is_no_escape_block_arg; procname; return_type}
+        in
         F.function_decl context.translation_unit_context context.tenv context.cfg decl block_data ;
         res
     | _ ->

infer/src/clang/cTrans_utils.ml

@@ -126,7 +126,10 @@ type trans_state =
   ; priority: priority_node
   ; var_exp_typ: (Exp.t * Typ.t) option
   ; opaque_exp: (Exp.t * Typ.t) option
-  ; is_fst_arg_objc_instance_method_call: bool }
+  ; is_fst_arg_objc_instance_method_call: bool
+  ; is_no_escape_block_arg: bool
+        (** Current to-be-translated instruction is being passed as argument in a position annotated
+            with NS_NOESCAPE *) }
 
 let default_trans_state context =
   { context
@@ -135,7 +138,8 @@ let default_trans_state context =
   ; priority= Free
   ; var_exp_typ= None
   ; opaque_exp= None
-  ; is_fst_arg_objc_instance_method_call= false }
+  ; is_fst_arg_objc_instance_method_call= false
+  ; is_no_escape_block_arg= false }
 
 
 type control =

infer/src/clang/cTrans_utils.mli

@@ -26,7 +26,8 @@ type trans_state =
   ; priority: priority_node
   ; var_exp_typ: (Exp.t * Typ.t) option
   ; opaque_exp: (Exp.t * Typ.t) option
-  ; is_fst_arg_objc_instance_method_call: bool }
+  ; is_fst_arg_objc_instance_method_call: bool
+  ; is_no_escape_block_arg: bool }
 
 val default_trans_state : CContext.t -> trans_state