reshape with array_view

[mmorale3]

Prerequisites

• Please check that a similar issue isn't already filed: https://github.com/issues?q=is%3Aissue+user%3Atriqs

Description

Not sure if this is a bug or expected behavior.
Consider the following unit tests (following style from tests/c++/nda_functions.cpp

TEST(reshape, reshape_view) { //NOLINT

nda::array<long, 1> a{1, 2, 3, 4, 5, 6}; // 1d array
auto v = reshape(a(nda::range::all), std::array{2, 3}); // v is an array_view<long,2> of size 2 x 3
v(0, nda::range::all) *= 10; // a is now {10, 20, 30, 4, 5, 6}

EXPECT_EQ_ARRAY(a, (nda::array<long, 1>{10, 20, 30, 4, 5, 6}));
}
//================================================

TEST(reshape, reshape_view_strided) { //NOLINT

nda::array<long, 1> a{1, 2, 3, 4, 5, 6}; // 1d array
auto v = reshape(a(nda::range(6)), std::array{2, 3}); // v is an array_view<long,2> of size 2 x 3
v(0, nda::range::all) *= 10; // a is now {10, 20, 30, 4, 5, 6}

EXPECT_EQ_ARRAY(a, (nda::array<long, 1>{10, 20, 30, 4, 5, 6}));
}
//================================================

The first one works as expected. The second one fails with the following message:

nda/c++/nda/./././layout/idx_map.hpp: In instantiation of 'class nda::idx_map<2, 0, 0, nda::layout_prop_e::strided_1d>':
nda/c++/nda/././linalg/../blas/../layout_transforms.hpp:121:32: required from 'auto nda::reshape(A&&, const std::array<Int, Rank>&) [with A = nda::basic_array_view<long int, 1, nda::basic_layout<0, 0, nda::layout_prop_e::strided_1d>, 'A', nda::default_accessor, nda::borrowed<> >; Int = int; auto R = 2]'
nda/test/c++/nda_functions.cpp:104:19: required from here
nda/c++/nda/./././layout/idx_map.hpp:105:38: error: static assertion failed: Error in nda::idx_map: StrideOrder can only be zero for 1D arrays
105 | static_assert((StrideOrder != 0) or (Rank == 1), "Error in nda::idx_map: StrideOrder can only be zero for 1D arrays");
| ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
nda/c++/nda/./././layout/idx_map.hpp:105:38: note: '((0 != 0) || (2 == 1))' evaluates to false
...
nda/c++/nda/././layout/./../stdutil/array.hpp: In instantiation of 'nda::stdutil::make_initialized_array<4, int>(int)::<lambda(std::index_sequence<I ...>)> [with long unsigned int ...Is = {0, 1, 2, 3}; std::index_sequence<I ...> = std::integer_sequence<long unsigned int, 0, 1, 2, 3>]':

Steps to Reproduce

Add unit tests described above to nda_functions.cpp.

Expected behavior: [What you expect to happen]

To be able to reshape an array_view (with strided_1d layout) in cases where the storage is contiguous (compact strides).

Actual behavior:

Compilation error.

Possibly coming from layout_transformations.hpp,

line ~125
using layout_t = typename std::decay_t::layout_policy_t::template mapping;

Versions

1.3.x (and all versions before).