use of `c()` on LHS gives C++ compilation error

[paciorek]

I have not dug into this (and I'll note that x[1:3] <- c(2,3,5) is fine).

nf <- nFunction(
    fun = function(x = 'numericVector') {
        x[c(2,3,5)] <- rep(1,3)
        return(x)
        returnType('numericVector')
    }
)
cnf <- nCompile(nf)

generated C++:

    Eigen::Tensor<double, 1>  nFun_17 ( Eigen::Tensor<double, 1> x )  {
RESET_EIGEN_ERRORS
IVEC_(0,nC(createTensor<double, 1>(2.0, 1), createTensor<double, 1>(3.0, 1), createTensor<double, 1>(5.0, 1)),x,true) = (repTimes(Eigen::Make_Length1_Tensor(1.0), 3.0)).eval();
return(x);
}

This might be the key compiler error output:

/system/linux/lib/R-24.04/4.6.0/x86_64/site-library/RcppEigen/include/unsupported/Eigen/CXX11/src/Tensor/TensorEvaluator.h:34:40: error: no type named ‘Dimensions’ in ‘class Eigen::TensorIndexByVecOp<0, Eigen::Tensor<double, 1>, Eigen::Tensor<double, 1>, true>’
   34 |   typedef typename Derived::Dimensions Dimensions;
      |                                        ^~~~~~~~~~
/system/linux/lib/R-24.04/4.6.0/x86_64/site-library/RcppEigen/include/unsupported/Eigen/CXX11/src/Tensor/TensorEvaluator.h:46:35: error: ‘IsAligned’ is not a member of ‘Eigen::TensorIndexByVecOp<0, Eigen::Tensor<double, 1>, Eigen::Tensor<double, 1>, true>’
   46 |     IsAligned          = Derived::IsAligned,
      |                                   ^~~~~~~~~
/system/linux/lib/R-24.04/4.6.0/x86_64/site-library/RcppEigen/include/unsupported/Eigen/CXX11/src/Tensor/TensorEvaluator.h:50:35: error: ‘Layout’ is not a member of ‘Eigen::TensorIndexByVecOp<0, Eigen::Tensor<double, 1>, Eigen::Tensor<double, 1>, true>’
   50 |     Layout             = Derived::Layout,
      |                                   ^~~~~~

[perrydv]

@paciorek I made PR #217 to fix this. I am running tests in Actions before merging.