use Shield instead of raw PROTECT/UNPROTECT

Author: romainfrancois

inst/include/Rcpp/api/meat/Vector.h

@@ -363,12 +363,11 @@ namespace Rcpp{
         Shield<SEXP> newnames( ::Rf_allocVector( STRSXP, n+1 ) ) ;
         int i=0;
         if( Rf_isNull(names) ){
-            SEXP dummy = PROTECT( Rf_mkChar("") );
+            Shield<SEXP> dummy( Rf_mkChar("") );
             for( ; it < this_end; ++it, ++target_it,i++ ){
                 *target_it = *it ;
                 SET_STRING_ELT( newnames, i , dummy );
             }
-            UNPROTECT(1);
         } else {
             for( ; it < this_end; ++it, ++target_it, i++ ){
                 *target_it = *it ;

inst/include/Rcpp/internal/wrap.h

@@ -811,7 +811,7 @@ inline SEXP rowmajor_wrap__dispatch( InputIterator first, int nrow, int ncol, ::
 			SET_VECTOR_ELT( out, j + ncol*i, ::Rcpp::wrap( *first) ) ;
 		}
 	}
-	SEXP dims = PROTECT( ::Rf_allocVector( INTSXP, 2) ); 
+	Shield<SEXP> dims( ::Rf_allocVector( INTSXP, 2) ); 
 	INTEGER(dims)[0] = nrow; 
 	INTEGER(dims)[1] = ncol; 
 	::Rf_setAttrib( out, R_DimSymbol, dims) ;