Updated bazel_to_cmake causes trouble

[dzenanz]

File "D:\a\im\_skbuild\win-amd64-3.8\cmake-build\_deps\tensorstore-src\tools\cmake\bazel_to_cmake\starlark\select.py", line 108, in evaluate
    return self.op(*(_try_evaluate(operand) for operand in self.operands))
TypeError: unsupported operand type(s) for |: 'dict' and 'dict'

as ocurred here.

This happens with c455741. The same CI used to work with b040186.

[jbms]

Oh, looks like we accidentally broke support for Python 3.8 by relying on that operator. If you use Python 3.9 it will work; I will see if there is a way to make it work with 3.8 though.

[dzenanz]

d5b12de still has this issue, as seen here: https://github.com/dzenanz/ITKIOOMEZarrNGFF/actions/runs/4683095325/jobs/8297768244.

[dzenanz]

Also here, for Linux: https://github.com/dzenanz/ITKIOOMEZarrNGFF/actions/runs/4683095325/jobs/8297767336.

[dzenanz]

In case the link rots, here is the error:

Found Python3: /opt/python/cp38-cp38/bin/python (found version "3.8.15") found components: Interpreter 
-- Found Patch: /usr/bin/patch  
-- [Protobuf] Found ZLIB: zlib  
-- [absl] Performing Test ABSL_INTERNAL_AT_LEAST_CXX17
-- [absl] Performing Test ABSL_INTERNAL_AT_LEAST_CXX17 - Success
Traceback (most recent call last):
  File "/work/_skbuild/linux-x86_64-3.8/cmake-build/_deps/tensorstore-src/tools/cmake/bazel_to_cmake/evaluation.py", line 283, in get_optional_target_info
    rule_info.impl()
  File "/work/_skbuild/linux-x86_64-3.8/cmake-build/_deps/tensorstore-src/tools/cmake/bazel_to_cmake/bzl_library/bazel_skylib.py", line 153, in <lambda>
    lambda: _expand_template_impl(context, target, out_target, **kwargs),
  File "/work/_skbuild/linux-x86_64-3.8/cmake-build/_deps/tensorstore-src/tools/cmake/bazel_to_cmake/bzl_library/bazel_skylib.py", line 191, in _expand_template_impl
    json.dumps(_context.evaluate_configurable(substitutions)).encode("utf-8"))
  File "/work/_skbuild/linux-x86_64-3.8/cmake-build/_deps/tensorstore-src/tools/cmake/bazel_to_cmake/starlark/invocation_context.py", line 121, in evaluate_configurable
    cast(Union[Select[T], SelectExpression[T]],
  File "/work/_skbuild/linux-x86_64-3.8/cmake-build/_deps/tensorstore-src/tools/cmake/bazel_to_cmake/starlark/select.py", line 108, in evaluate
    return self.op(*(_try_evaluate(operand) for operand in self.operands))
  File "/work/_skbuild/linux-x86_64-3.8/cmake-build/_deps/tensorstore-src/tools/cmake/bazel_to_cmake/starlark/select.py", line 108, in <genexpr>
    return self.op(*(_try_evaluate(operand) for operand in self.operands))
  File "/work/_skbuild/linux-x86_64-3.8/cmake-build/_deps/tensorstore-src/tools/cmake/bazel_to_cmake/starlark/select.py", line 104, in _try_evaluate
    return t.evaluate(test_condition)
  File "/work/_skbuild/linux-x86_64-3.8/cmake-build/_deps/tensorstore-src/tools/cmake/bazel_to_cmake/starlark/select.py", line 108, in evaluate
    return self.op(*(_try_evaluate(operand) for operand in self.operands))
TypeError: unsupported operand type(s) for |: 'NoneType' and 'DictWithUnion'

[jbms]

Thanks for reporting this --- there was a missing return new here:

tensorstore/tools/cmake/bazel_to_cmake/dict_union_polyfill.py

Line 44 in d5b12de

And also in our CI system, CMake was finding an unexpected Python version via the Windows registry and therefore this code path wasn't being properly tested.

I will push out a fixed version shortly.

[dzenanz]

I confirm that 2868eab fixes the problem.