[frontend] Do not die when selector is unknown in objc boxed expr

Summary:
Sometimes clang9 does not return a boxing method (a name of function to apply), e.g., [@("str")].
To solve the issue, this diff uses "unknownSelector:" instead of giving up the translation.

Reviewed By: dulmarod

Differential Revision: D18831844

fbshipit-source-id: b9324ba39

infer/src/clang/cTrans.ml

@@ -3483,12 +3483,14 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
         floatingLiteral_trans trans_state expr_info float_string
     | CXXScalarValueInitExpr (_, _, expr_info) ->
         cxxScalarValueInitExpr_trans trans_state expr_info
-    | ObjCBoxedExpr (stmt_info, stmts, info, boxed_expr_info) -> (
-      match boxed_expr_info.Clang_ast_t.obei_boxing_method with
-      | Some sel ->
-          objCBoxedExpr_trans trans_state info sel stmt_info stmts
-      | None ->
-          assert false )
+    | ObjCBoxedExpr (stmt_info, stmts, info, boxed_expr_info) ->
+        (* Sometimes clang does not return a boxing method (a name of function to apply), e.g.,
+           [@("str")].  In that case, it uses "unknownSelector:" instead of giving up the
+           translation. *)
+        let sel =
+          Option.value boxed_expr_info.Clang_ast_t.obei_boxing_method ~default:"unknownSelector:"
+        in
+        objCBoxedExpr_trans trans_state info sel stmt_info stmts
     | ObjCArrayLiteral (stmt_info, stmts, expr_info, array_literal_info) ->
         objCArrayLiteral_trans trans_state expr_info stmt_info stmts array_literal_info
     | ObjCDictionaryLiteral (stmt_info, stmts, expr_info, dict_literal_info) ->

infer/tests/codetoanalyze/objc/frontend/boxing/Boxing.m

@@ -42,4 +42,10 @@
   ;
 }
 
+- (NSString*)getString {
+  NSString* s = @("hello world");
+  return s;
+  ;
+}
+
 @end

infer/tests/codetoanalyze/objc/frontend/boxing/Boxing.m.dot

@@ -98,4 +98,19 @@ digraph cfg {
 	
 
 	 "getS#Boxing#instance.97ccd331527b54376eb9b2b822cb25a3_4" -> "getS#Boxing#instance.97ccd331527b54376eb9b2b822cb25a3_3" ;
+"getString#Boxing#instance.0cdd84065923a1c621289a9de4707559_1" [label="1: Start Boxing::getString\nFormals:  self:Boxing*\nLocals:  s:NSString* \n  " color=yellow style=filled]
+	
+
+	 "getString#Boxing#instance.0cdd84065923a1c621289a9de4707559_1" -> "getString#Boxing#instance.0cdd84065923a1c621289a9de4707559_4" ;
+"getString#Boxing#instance.0cdd84065923a1c621289a9de4707559_2" [label="2: Exit Boxing::getString \n  " color=yellow style=filled]
+	
+
+"getString#Boxing#instance.0cdd84065923a1c621289a9de4707559_3" [label="3:  Return Stmt \n   n$19=*&s:NSString* [line 47, column 10]\n  *&return:NSString*=n$19 [line 47, column 3]\n " shape="box"]
+	
+
+	 "getString#Boxing#instance.0cdd84065923a1c621289a9de4707559_3" -> "getString#Boxing#instance.0cdd84065923a1c621289a9de4707559_2" ;
+"getString#Boxing#instance.0cdd84065923a1c621289a9de4707559_4" [label="4:  DeclStmt \n   VARIABLE_DECLARED(s:NSString*); [line 46, column 3]\n  n$20=_fun_NSString::unknownSelector:(\"hello world\":char*) [line 46, column 17]\n  *&s:NSString*=n$20 [line 46, column 3]\n " shape="box"]
+	
+
+	 "getString#Boxing#instance.0cdd84065923a1c621289a9de4707559_4" -> "getString#Boxing#instance.0cdd84065923a1c621289a9de4707559_3" ;
 }