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TypeError: cannot deepcopy this pattern object

See original GitHub issue

Describe the bug With Meson 0.56 and the example below, I get a “TypeError: cannot deepcopy this pattern object” exception (the example in #7457 does not give an exception on this system with 0.56). If I rollback to 0.55 this example works as expected, but the example in #7457 throws the exception.

To Reproduce meson.build

project('cmake_dep_regression','cpp')
cmake = import('cmake')

xtensor_dep = dependency('xtensor',
    version: ['>=0.21.4', '<1.0.0'],
    fallback: ['xtensor', 'xtensor_dep'],
    include_type: 'system',
    method : 'pkg-config')
exe1 = executable('main_xt', ['main_xt.cpp'], dependencies: [xtensor_dep])

# xerces_dep = cmake.subproject('xerces-c').dependency('xerces-c').as_system('system')
# exe1 = executable('main_cm', ['main_cm.cpp'], dependencies: [xerces_dep])

main_xt.cpp

#include <iostream>
#include <xtensor/xarray.hpp>
#include <xtensor/xio.hpp>
#include <xtensor/xview.hpp>

int main(void) {
  xt::xarray<double> arr1
      {{1.0, 2.0, 3.0},
       {2.0, 5.0, 7.0},
       {2.0, 5.0, 7.0}};

  std::cout << arr1 << std::endl;
  
  return 0;
}

xtensor.wrap

[wrap-file]
directory=xtensor-0.21.5

source_url=https://github.com/xtensor-stack/xtensor/archive/0.21.5.zip
source_filename=xtensor-0.21.5.zip
source_hash=f08aca41dc89128524dec04c82b590d9e0f1e923311e82bab9f024c99e7bb73a

patch_url=https://github.com/kyonifer/meson-wraps/raw/master/zips/xtensor-0.21.5-patches-1.zip
patch_filename=xtensor-0.21.5-patches-1.zip
patch_hash=d935d94a6b80d5466114cb29e49c2a358f42d0a1edceaa91f1ff76833b6c03e2

xtl.wrap

[wrap-file]
directory=xtl-0.6.12

source_url=https://github.com/xtensor-stack/xtl/archive/0.6.12.zip
source_filename=xtl-0.6.12.zip
source_hash=4ad3204312f72bce52951fb69acd1cd09e7f20f52c7e3b684140a4484acb5597

patch_url=https://github.com/kyonifer/meson-wraps/raw/master/zips/xtl-0.6.12-patches-2.zip
patch_filename=xtl-0.6.12-patches-2.zip
patch_hash=a65faee12aec22dd07f640863a0cae1b5310ea804e5d87c4a5ed73ee357ba6e1

nlohmann_json.wrap

[wrap-file]
directory = json-3.5.0

source_url = https://github.com/nlohmann/json/archive/v3.5.0.zip
source_filename = nlohmann_json-3.5.0.zip
source_hash = a65127f2797487cf07fdf1caacdff56ba3197ff02095cf0fde5bb35e91c86980

patch_url=https://github.com/kyonifer/meson-wraps/raw/master/zips/nlohmann_json-3.5.0-patches-1.zip
patch_filename=nlohmann_json-3.5.0-patches-1.zip
patch_hash=6585b48ef5cbf133d9c689c0b3748cc0ecb7324260ce87b96cf00d09bb0a1cdd

Expected behavior successful build with both 0.55 and 0.56.

system parameters

Ubuntu 18.04.4 LTS Python 3.6.9 meson 0.55.0 (works) meson 0.56.0 (fails) ninja 1.8.2