[clang] call a skip function in case of unimplemented feature

Summary: Returning the list of sub-expressions is not right and can cause assertion failures elsewhere in the frontend.

Reviewed By: dulmarod

Differential Revision: D7813493

fbshipit-source-id: 33ac9c1

infer/src/IR/BUILTINS.ml

@@ -50,6 +50,9 @@ module type S = sig
 
   val __infer_fail : t
 
+  val __infer_skip : t
+  (** used to represent behavior that is not modeled in infer *)
+
   val __instanceof : t
   (** [__instanceof(val,typ)] implements java's [val instanceof typ] *)
 

infer/src/IR/BuiltinDecl.ml

@@ -71,6 +71,8 @@ let __infer_assume = create_procname "__infer_assume"
 
 let __infer_fail = create_procname "__infer_fail"
 
+let __infer_skip = create_procname "__infer_skip"
+
 let __instanceof = create_procname "__instanceof"
 
 let __method_set_ignore_attribute = create_procname "__method_set_ignore_attribute"

infer/src/biabduction/BuiltinDefn.ml

@@ -886,6 +886,8 @@ let __infer_assume = Builtin.register BuiltinDecl.__infer_assume execute___infer
 (* externally create new errors *)
 let __infer_fail = Builtin.register BuiltinDecl.__infer_fail execute___infer_fail
 
+let __infer_skip = Builtin.register BuiltinDecl.__infer_skip execute_skip
+
 (* [__instanceof(val,typ)] implements java's [val instanceof typ] *)
 let __instanceof = Builtin.register BuiltinDecl.__instanceof execute___instanceof
 

infer/src/clang/cTrans.ml

@@ -992,7 +992,6 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
     let context = trans_state.context in
     let fn_type_no_ref = CType_decl.get_type_from_expr_info expr_info context.CContext.tenv in
     let function_type = add_reference_if_glvalue fn_type_no_ref expr_info in
-    let procname = Procdesc.get_proc_name context.CContext.procdesc in
     let sil_loc = CLocation.get_sil_location si context in
     (* First stmt is the function expr and the rest are params *)
     let fun_exp_stmt, params_stmt =
@@ -1039,6 +1038,7 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
           if Int.equal (List.length params) (List.length params_stmt) then params
           else
             (* FIXME(t21762295) this is reachable *)
+            let procname = Procdesc.get_proc_name context.CContext.procdesc in
             CFrontend_config.incorrect_assumption __POS__ si.Clang_ast_t.si_source_range
               "In call to %a: stmt_list and res_trans_par.exps must have same size but they don't:@\n\
                stmt_list(%d)=[%a]@\n\
@@ -3082,8 +3082,10 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
     {empty_res_trans with exps= [(CTrans_utils.undefined_expression (), typ)]}
 
 
-  (* no-op translated for unsupported instructions that will at least translate subexpressions *)
-  and skip_unimplemented trans_state stmts = instructions trans_state stmts
+  (** no-op translated for unsupported instructions that will at least translate subexpressions *)
+  and skip_unimplemented ~reason trans_state stmts =
+    call_function_with_args reason BuiltinDecl.__infer_skip trans_state stmts
+
 
   (* Translates a clang instruction into SIL instructions. It takes a       *)
   (* a trans_state containing current info on the translation and it returns *)
@@ -3306,8 +3308,12 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
        sub-expressions *)
     | ObjCAvailabilityCheckExpr (_, _, expr_info, _) ->
         trans_into_undefined_expr trans_state expr_info
-    | ExtVectorElementExpr (_, stmts, _) | ShuffleVectorExpr (_, stmts, _) ->
-        skip_unimplemented trans_state stmts
+    | ExtVectorElementExpr (stmt_info, stmts, _) | ShuffleVectorExpr (stmt_info, stmts, _) ->
+        skip_unimplemented
+          ~reason:
+            (Printf.sprintf "unimplemented construct: %s"
+               (Clang_ast_proj.get_stmt_kind_string instr))
+          trans_state stmt_info stmts
     (* Infer somehow ended up in templated non instantiated code - right now
        it's not supported and failure in those cases is expected. *)
     | SubstNonTypeTemplateParmExpr _

infer/tests/codetoanalyze/cpp/frontend/vectors/shuffle_vector.cpp.dot

@@ -7,7 +7,7 @@ digraph cfg {
 "simple#17639603251097432993.e5c9feb95ecff69f23df6ce422f34819_2" [label="2: Exit simple \n  " color=yellow style=filled]
 	
 
-"simple#17639603251097432993.e5c9feb95ecff69f23df6ce422f34819_3" [label="3:  Return Stmt \n   n$0=*&vec:void [line 12, column 44]\n  *&return:void=n$0 [line 12, column 37]\n " shape="box"]
+"simple#17639603251097432993.e5c9feb95ecff69f23df6ce422f34819_3" [label="3:  Return Stmt \n   _fun___infer_skip(&vec:void&) [line 12, column 44]\n  n$0=*-1:void [line 12, column 44]\n  *&return:void=n$0 [line 12, column 37]\n " shape="box"]
 	
 
 	 "simple#17639603251097432993.e5c9feb95ecff69f23df6ce422f34819_3" -> "simple#17639603251097432993.e5c9feb95ecff69f23df6ce422f34819_2" ;