Merge pull request #908 from romainfrancois/bug/Matrix-no-init

Matrix(no_init(,)) sets the nrows member

Author: eddelbuettel

inst/include/Rcpp/vector/Matrix.h

@@ -89,9 +89,7 @@ class Matrix : public Vector<RTYPE, StoragePolicy>, public MatrixBase<RTYPE, tru
     }
     Matrix& operator=( const SubMatrix<RTYPE>& ) ;
 
-    explicit Matrix( const no_init_matrix& obj) {
-        VECTOR::set__( Rf_allocMatrix( RTYPE, obj.nrow(), obj.ncol() ) );
-    }
+    explicit Matrix( const no_init_matrix& obj) : VECTOR(Rf_allocMatrix(RTYPE, obj.nrow(), obj.ncol())), nrows(obj.nrow()) {}
 
     inline int ncol() const {
         return VECTOR::dims()[1];

inst/unitTests/cpp/Matrix.cpp

@@ -288,6 +288,12 @@ NumericMatrix runit_no_init_matrix_ctor() {
     return x;
 }
 
+// [[Rcpp::export]]
+int runit_no_init_matrix_ctor_nrow() {
+    NumericMatrix x(no_init(2, 2));
+    return x.nrow();
+}
+
 void runit_const_Matrix_column_set( NumericMatrix::Column& col1, const NumericMatrix::Column& col2 ){
     col1 = col2 ;
 }

inst/unitTests/runit.Matrix.R

@@ -202,6 +202,11 @@ if (.runThisTest) {
         checkEquals(m, matrix(c(0, 1, 2, 3), nrow = 2))
     }
 
+    test.NumericMatrix.no.init.ctor.nrow <- function() {
+        nrow <- runit_no_init_matrix_ctor_nrow()
+        checkEquals(nrow, 2L)
+    }
+
     test.NumericMatrix.const.Column <- function(){
       m <- matrix(as.numeric(1:9), nrow = 3)
       res <- runit_const_Matrix_column(m)