Commit Graph

600 Commits

Author SHA1 Message Date
Steve R. Sun
bdc66adad4
Merge branch 'pybind:master' into master 2022-03-18 07:57:07 +08:00
JonTriebenbach
8b1944d390
Remove idioms in code comments (#3809) 2022-03-17 12:51:16 -07:00
Axel Huebl
a7e7a6e846
Docs: No Strip in Debug (#3779)
The docs were not 100% the same as we advertise with our
tooling function: most users do not want to strip symbols
in Debug builds.
2022-03-17 11:21:28 -07:00
Steve R. Sun
574a47091e
Merge branch 'master' into master 2022-02-15 07:52:48 +08:00
Ralf W. Grosse-Kunstleve
a97e9d8cac
Dropping MSVC 2015 (#3722)
* Changing `_MSC_VER` guard to `< 1910` (dropping MSVC 2015).

* Removing MSVC 2015 from ci.yml, and .appveyor.yml entirely.

* Bringing back .appveyor.yml from master.

* appveyor Visual Studio 2017

* 1st manual pass, builds & tests with unix_clang, before pre-commit.

* After clang-format (via pre-commit).

* Manual pass looking for "2015", builds & tests with unix_clang, before pre-commit.

* Backtracking for include/pybind11 changes in previous commit.

git checkout d07865846c include/pybind11/attr.h include/pybind11/detail/common.h include/pybind11/functional.h

--------------------

CI #4160 errors observed:

2a26873727
https://github.com/pybind/pybind11/runs/5168332130?check_suite_focus=true

$ grep ' error C' *.txt | sed 's/2022-02-12[^ ]*//' | sed 's/^[0-9][0-9]*//' | sed 's/^.*\.txt: //' | sort | uniqD:\a\pybind11\pybind11\include\pybind11\cast.h(1364,1): error C2752: 'pybind11::detail::type_caster<Eigen::Ref<Eigen::Vector3f,0,pybind11::EigenDStride>,void>': more than one partial specialization matches the template argument list [D:\a\pybind11\pybind11\build\tests\pybind11_tests.vcxproj]

d:\a\pybind11\pybind11\include\pybind11\detail/common.h(1023): error C2737: 'pybind11::overload_cast': 'constexpr' object must be initialized [D:\a\pybind11\pybind11\build\tests\cross_module_gil_utils.vcxproj]
d:\a\pybind11\pybind11\include\pybind11\detail/common.h(1023): error C2737: 'pybind11::overload_cast': 'constexpr' object must be initialized [D:\a\pybind11\pybind11\build\tests\pybind11_cross_module_tests.vcxproj]
d:\a\pybind11\pybind11\include\pybind11\detail/common.h(1023): error C2737: 'pybind11::overload_cast': 'constexpr' object must be initialized [D:\a\pybind11\pybind11\build\tests\pybind11_tests.vcxproj]
d:\a\pybind11\pybind11\include\pybind11\detail/common.h(1023): error C2737: 'pybind11::overload_cast': 'constexpr' object must be initialized [D:\a\pybind11\pybind11\build\tests\test_embed\external_module.vcxproj]
D:\a\pybind11\pybind11\include\pybind11\detail/common.h(624): fatal error C1001: Internal compiler error. [D:\a\pybind11\pybind11\build\tests\pybind11_tests.vcxproj]
D:\a\pybind11\pybind11\include\pybind11\detail/common.h(624): fatal error C1001: Internal compiler error. [D:\a\pybind11\pybind11\tests\pybind11_tests.vcxproj]

$ grep ': error C2737' *.txt | sed 's/^.*MSVC//' | sed 's/___.*//' | sort | uniq

_2017

$ grep ': error C2752' *.txt

3______3.8_____MSVC_2019_____x86_-DCMAKE_CXX_STANDARD=17.txt:2022-02-12T16:12:45.9921122Z D:\a\pybind11\pybind11\include\pybind11\cast.h(1364,1): error C2752: 'pybind11::detail::type_caster<Eigen::Ref<Eigen::Vector3f,0,pybind11::EigenDStride>,void>': more than one partial specialization matches the template argument list [D:\a\pybind11\pybind11\build\tests\pybind11_tests.vcxproj]

$ grep ': fatal error C1001:' *.txt

10______pypy-3.8-v7.3.7_____windows-2022_____x64.txt:2022-02-12T16:12:56.3163683Z D:\a\pybind11\pybind11\include\pybind11\detail/common.h(624): fatal error C1001: Internal compiler error. [D:\a\pybind11\pybind11\tests\pybind11_tests.vcxproj]
1______3.6_____MSVC_2019_____x86.txt:2022-02-12T16:12:47.6774625Z D:\a\pybind11\pybind11\include\pybind11\detail/common.h(624): fatal error C1001: Internal compiler error. [D:\a\pybind11\pybind11\build\tests\pybind11_tests.vcxproj]
16______3.6_____windows-latest_____x64_-DPYBIND11_FINDPYTHON=ON.txt:2022-02-12T16:12:27.0556151Z D:\a\pybind11\pybind11\include\pybind11\detail/common.h(624): fatal error C1001: Internal compiler error. [D:\a\pybind11\pybind11\tests\pybind11_tests.vcxproj]
17______3.9_____windows-2019_____x64.txt:2022-02-12T16:12:30.3822566Z D:\a\pybind11\pybind11\include\pybind11\detail/common.h(624): fatal error C1001: Internal compiler error. [D:\a\pybind11\pybind11\tests\pybind11_tests.vcxproj]
2______3.7_____MSVC_2019_____x86.txt:2022-02-12T16:12:38.7018911Z D:\a\pybind11\pybind11\include\pybind11\detail/common.h(624): fatal error C1001: Internal compiler error. [D:\a\pybind11\pybind11\build\tests\pybind11_tests.vcxproj]
6______3.6_____windows-2022_____x64.txt:2022-02-12T16:12:00.4513642Z D:\a\pybind11\pybind11\include\pybind11\detail/common.h(624): fatal error C1001: Internal compiler error. [D:\a\pybind11\pybind11\tests\pybind11_tests.vcxproj]
7______3.9_____windows-2022_____x64.txt:2022-02-12T16:11:43.6306160Z D:\a\pybind11\pybind11\include\pybind11\detail/common.h(624): fatal error C1001: Internal compiler error. [D:\a\pybind11\pybind11\tests\pybind11_tests.vcxproj]
8______3.10_____windows-2022_____x64.txt:2022-02-12T16:11:49.9589644Z D:\a\pybind11\pybind11\include\pybind11\detail/common.h(624): fatal error C1001: Internal compiler error. [D:\a\pybind11\pybind11\tests\pybind11_tests.vcxproj]
9______pypy-3.7-v7.3.7_____windows-2022_____x64.txt:2022-02-12T16:11:53.7912112Z D:\a\pybind11\pybind11\include\pybind11\detail/common.h(624): fatal error C1001: Internal compiler error. [D:\a\pybind11\pybind11\tests\pybind11_tests.vcxproj]

* common.h: is_template_base_of

* Re-applying 4 changes from 2a26873727 that work universally.

* `overload_cast = {};` only for MSVC 2017 and Clang 5

* Refining condition for using is_template_base_of workaround.

* Undoing MSVC 2015 workaround in test_constants_and_functions.cpp

* CentOS7: silence_unused_warnings

* Tweaks in response to reviews.

* Adding windows-2022 C++20

* Trying another way of adding windows-2022 C++20
2022-02-14 11:36:22 -08:00
Henry Schreiner
522c59ceb2
chore: drop Python 3.5 (#3719)
* chore: drop Python 3.5 support

* chore: more fstrings with flynt's help

* ci: drop Python 3.5

* chore: bump dependency versions

* docs: touch up py::args

* tests: remove deprecation warning

* Ban smartquotes

* Very minor tweaks (by-product of reviewing PR #3719).

Co-authored-by: Aaron Gokaslan <skylion.aaron@gmail.com>
Co-authored-by: Ralf W. Grosse-Kunstleve <rwgk@google.com>
2022-02-11 19:06:16 -05:00
Ralf W. Grosse-Kunstleve
6493f496e3
Python 2 removal part 1: tests (C++ code is intentionally ~untouched) (#3688)
* `#error BYE_BYE_GOLDEN_SNAKE`

* Removing everything related to 2.7 from ci.yml

* Commenting-out Centos7

* Removing `PYTHON: 27` from .appveyor.yml

* "PY2" removal, mainly from tests. C++ code is not touched.

* Systematic removal of `u` prefix from `u"..."` and `u'...'` literals. Collateral cleanup of a couple minor other things.

* Cleaning up around case-insensitive hits for `[^a-z]py.*2` in tests/.

* Removing obsolete Python 2 mention in compiling.rst

* Proper `#error` for Python 2.

* Using PY_VERSION_HEX to guard `#error "PYTHON 2 IS NO LONGER SUPPORTED.`

* chore: bump pre-commit

* style: run pre-commit for pyupgrade 3+

* tests: use sys.version_info, not PY

* chore: more Python 2 removal

* Uncommenting Centos7 block (PR #3691 showed that it is working again).

* Update pre-commit hooks

* Fix pre-commit hook

* refactor: remove Python 2 from CMake

* refactor: remove Python 2 from setup code

* refactor: simplify, better static typing

* feat: fail with nice messages

* refactor: drop Python 2 C++ code

* docs: cleanup for Python 3

* revert: intree

revert: intree

* docs: minor touchup to py2 statement

Co-authored-by: Henry Schreiner <henryschreineriii@gmail.com>
Co-authored-by: Aaron Gokaslan <skylion.aaron@gmail.com>
2022-02-10 18:28:08 -08:00
Steve R. Sun
38ba7294fe
Merge branch 'pybind:master' into master 2022-02-06 10:27:12 +08:00
Sebastian Koslowski
94a948722f
docs: fix imported target name (#3689) 2022-02-05 19:11:59 -05:00
Steve R. Sun
cd2b9d4b09
Merge branch 'pybind:master' into master 2022-02-05 10:37:45 +08:00
Henry Schreiner
36813cfa12
chore: back to work 2022-02-03 12:44:10 -05:00
Henry Schreiner
0f6ad9105c
docs: update changelog for 2.9.1 (#3670)
* docs: update changelog for 2.9.1

* Update changelog.rst

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update changelog.rst

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
2022-02-02 16:08:44 -05:00
Steve R. Sun
611c5aecc2
Merge branch 'pybind:master' into master 2022-02-01 10:14:31 +08:00
Dustin Spicuzza
177928840e
Document how to bind templates (#3665) 2022-01-29 14:38:30 -08:00
Steve R. Sun
718f195f7b
Merge branch 'pybind:master' into master 2022-01-27 09:42:06 +08:00
yangliz5
dedda228f4
Fix a typo in class.rst (#3648)
Fix a typo in class.rst
2022-01-25 22:32:33 -08:00
Steve R. Sun
4c9ab5cc01
Merge branch 'pybind:master' into master 2022-01-20 09:04:02 +08:00
Nimrod
9ec1128c7a
Fix typo in doc (#3628) 2022-01-18 23:22:42 -08:00
Steve R. Sun
fa0fedec32
Merge branch 'pybind:master' into master 2021-12-29 23:20:31 +08:00
Henry Schreiner
9b4f71d12d
docs: remove duplication in changelog for 2.9.0 2021-12-28 12:19:17 -05:00
Henry Schreiner
45f792efdd
chore: prepare for 2.9 2021-12-28 10:47:21 -05:00
Steve R. Sun
f60a63e0f2
Merge branch 'master' into master 2021-12-25 12:24:02 +08:00
Henry Schreiner
d4b9f3471f
docs: update changelog (#3556)
* docs: update changelog

* Update changelog.rst

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
2021-12-21 16:28:23 -05:00
Henry Schreiner
39fbc7992b
fix: avoiding usage of _ if already defined (#3423)
* fix: avoid usage of _

* ci: test _ defined

* docs: include change in docs

* fix: add a test and comment

* refactor: const_str -> const_name
2021-12-21 14:24:21 -05:00
sun1638650145
74b027e586 Strictly defined integer. 2021-12-09 17:54:07 +08:00
sun1638650145
9d846f6e27 Add doc of py::numpy_scalar 2021-12-07 11:22:45 +08:00
Henry Schreiner
cd176ceeff
chore: update changelog with recent PRs (#3524) 2021-12-02 16:41:47 -05:00
ngc92
56322dafc9
fixed include for filesystem::path (#3482) 2021-11-18 14:06:04 -05:00
Guillaume Jacquenot
1eb59963c7
Removed duplicated word in docs/advanced/exceptions.rst (#3476) 2021-11-16 17:32:01 -05:00
Guillaume Jacquenot
e450eb62c2
Removed duplicated word in docs/advanced/cast/eigen.rst (#3458) 2021-11-12 10:53:43 -05:00
Henry Schreiner
aebd21b53c
docs: rework CI a bit, more modern skipping (#3424)
* docs: rework CI a bit, more modern skipping

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
2021-11-10 12:13:10 -05:00
Henry Schreiner
a61e354e42
docs: touch up manual release suggestion (#3422) 2021-11-05 22:48:27 -04:00
Chad B. Hovey
dd2d12721c
Correct "which" versus "that" error. (#3430) 2021-11-01 12:01:27 -04:00
Jason Rhinelander
e7c9753f1d
feat: allow kw-only args after a py::args (#3402)
* Simply has_kw_only_args handling

This simplifies tracking the number of kw-only args by instead tracking
the number of positional arguments (which is really what we care about
everywhere this is used).

* Allow keyword-only arguments to follow py::args

This removes the constraint that py::args has to be last (or
second-last, with py::kwargs) and instead makes py::args imply
py::kw_only for any remaining arguments, allowing you to bind a function
that works the same way as a Python function such as:

    def f(a, *args, b):
        return a * b + sum(args)

    f(10, 1, 2, 3, b=20)  # == 206

With this change, you can bind such a function using:

    m.def("f", [](int a, py::args args, int b) { /* ... */ },
        "a"_a, "b"_a);

Or, to be more explicit about the keyword-only arguments:

    m.def("g", [](int a, py::args args, int b) { /* ... */ },
        "a"_a, py::kw_only{}, "b"_a);

(The only difference between the two is that the latter will fail at
binding time if the `kw_only{}` doesn't match the `py::args` position).

This doesn't affect backwards compatibility at all because, currently,
you can't have a py::args anywhere except the end/2nd-last.

* Take args/kwargs by const lvalue ref

Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>

Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>
2021-10-28 23:16:55 -04:00
Ralf W. Grosse-Kunstleve
f7b499615e
[skip ci] Tweaks in preparation for the 2.8.1 release. (#3421) 2021-10-27 14:35:10 -07:00
Henry Schreiner
f1594cb960
docs: changelog update for 2.8.1 (#3416)
* docs: changelog update for 2.8.1

* chore: add one more entry

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
2021-10-27 15:08:59 -04:00
Aaron Gokaslan
78ee782bd4
feat: Add C++ binding to throw AttributeError (#3387)
* Add C++ bindings to throw AttributeError

* Fix formatting bug
2021-10-23 00:07:22 -04:00
Henry Schreiner
f791dc8648
fix: deprecate make_simple_namespace, fix Python 3.11 (#3374)
* fix: deprecate make_simple_namespace, fix Python 3.11

* docs: update links
2021-10-19 14:39:29 -04:00
Aaron Gokaslan
f4c81e0877
maint: Add additional linter-related pre-commit hooks (#3337)
* Add additional pygrep pre-commit hooks

* Remove useless noqas with hook

* Fix all single rst backticks

* Simplify mypy pre-commit hook with upstream fixes

* Add back missing comment

* Add one last pygrep hook
2021-10-08 08:38:04 -04:00
Bruce Merry
47ed124f37
Fix some formatting in the v2.8.0 changelog (#3339)
[skipci]
2021-10-08 08:27:38 -04:00
Henry Schreiner
ba9f919b85
chore: get back to work after 2.8.0 2021-10-04 17:37:27 -04:00
Henry Schreiner
591db0b930 docs: update CHANGELOG for 2.8 2021-10-04 15:20:10 -04:00
xaedes
b4e1ab8caa
Docs: Demonstrate non-enum internal types in example (#3314)
* Docs: Demonstrate non-enum internal types in example

Previously example only demonstrated internal enumeration type. 
To show that it works for other internal types the same way the example was updated with an additional struct Pet::Attributes type.

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
2021-09-30 14:45:06 -04:00
Philipp Bucher
c9bbf8d2ee docs: fix minor typo (#3311) 2021-09-28 10:17:52 -04:00
Henry Schreiner
6bce3bd72e
docs: update CHANGELOG (#3304) 2021-09-24 23:48:38 -04:00
Jeremy Maitin-Shepard
62c4909cce
Add custom_type_setup attribute (#3287)
* Fix `pybind11::object::operator=` to be safe if `*this` is accessible from Python

* Add `custom_type_setup` attribute

This allows for custom modifications to the PyHeapTypeObject prior to
calling `PyType_Ready`.  This may be used, for example, to define
`tp_traverse` and `tp_clear` functions.
2021-09-24 12:08:22 -07:00
Henry Schreiner
21282e645a
feat: reapply fixed version of #3271 (#3293)
* Add make_value_iterator (#3271)

* Add make_value_iterator

This is the counterpart to make_key_iterator, and will allow
implementing a `value` method in `bind_map` (although doing so is left
for a subsequent PR).

I made a few design changes to reduce copy-and-paste boilerplate.
Previously detail::iterator_state had a boolean template parameter to
indicate whether it was being used for make_iterator or
make_key_iterator. I replaced the boolean with a class that determines
how to dereference the iterator. This allows for a generic
implementation of `__next__`.

I also added the ValueType and Extra... parameters to the iterator_state
template args, because I think it was a bug that they were missing: if
make_iterator is called twice with different values of these, only the
first set has effect (because the state class is only registered once).
There is still a potential issue in that the *values* of the extra
arguments are latched on the first call, but since most policies are
empty classes this should be even less common.

* Add some remove_cv_t to appease clang-tidy

* Make iterator_access and friends take reference

For some reason I'd accidentally made it take a const value, which
caused some issues with third-party packages.

* Another attempt to remove remove_cv_t from iterators

Some of the return types were const (non-reference) types because of the
pecularities of decltype: `decltype((*it).first)` is the *declared* type
of the member of the pair, rather than the type of the expression. So if
the reference type of the iterator is `pair<const int, int> &`, then the
decltype is `const int`. Wrapping an extra set of parentheses to form
`decltype(((*it).first))` would instead give `const int &`.

This means that the existing make_key_iterator actually returns by value
from `__next__`, rather than by reference. Since for mapping types, keys
are always const, this probably hasn't been noticed, but it will affect
make_value_iterator if the Python code tries to mutate the returned
objects. I've changed things to use double parentheses so that
make_iterator, make_key_iterator and make_value_iterator should now all
return the reference type of the iterator. I'll still need to add a test
for that; for now I'm just checking whether I can keep Clang-Tidy happy.

* Add back some NOLINTNEXTLINE to appease Clang-Tidy

This is favoured over using remove_cv_t because in some cases a const
value return type is deliberate (particularly for Eigen).

* Add a unit test for iterator referencing

Ensure that make_iterator, make_key_iterator and make_value_iterator
return references to the container elements, rather than copies. The
test for make_key_iterator fails to compile on master, which gives me
confidence that this branch has fixed it.

* Make the iterator_access etc operator() const

I'm actually a little surprised it compiled at all given that the
operator() is called on a temporary, but I don't claim to fully
understand all the different value types in C++11.

* Attempt to work around compiler bugs

https://godbolt.org/ shows an example where ICC gets the wrong result
for a decltype used as the default for a template argument, and CI also
showed problems with PGI. This is a shot in the dark to see if it fixes
things.

* Make a test constructor explicit (Clang-Tidy)

* Fix unit test on GCC 4.8.5

It seems to require the arguments to the std::pair constructor to be
implicitly convertible to the types in the pair, rather than just
requiring is_constructible.

* Remove DOXYGEN_SHOULD_SKIP_THIS guards

Now that a complex decltype expression has been replaced by a simpler
nested type, I'm hoping Doxygen will be able to build it without issues.

* Add comment to explain iterator_state template params

* fix: regression in #3271

Co-authored-by: Bruce Merry <1963944+bmerry@users.noreply.github.com>
2021-09-23 15:06:07 -04:00
Henry Schreiner
2fa3fcfda5 Revert "Add make_value_iterator (#3271)"
This reverts commit ee0c5ee405.
2021-09-22 23:10:03 -04:00
Aaron Gokaslan
0fb981b219
Add blacken-docs and pycln pre-commit hooks (#3292)
* Apply blacken-docs and fix language-hints

* Add blacken-docs pre-commit hook

* Add pycln pre-commit hook

* Enable a few builtin hooks

* Black no longer ignores pyi files
2021-09-22 15:38:50 -04:00
Bruce Merry
ee0c5ee405
Add make_value_iterator (#3271)
* Add make_value_iterator

This is the counterpart to make_key_iterator, and will allow
implementing a `value` method in `bind_map` (although doing so is left
for a subsequent PR).

I made a few design changes to reduce copy-and-paste boilerplate.
Previously detail::iterator_state had a boolean template parameter to
indicate whether it was being used for make_iterator or
make_key_iterator. I replaced the boolean with a class that determines
how to dereference the iterator. This allows for a generic
implementation of `__next__`.

I also added the ValueType and Extra... parameters to the iterator_state
template args, because I think it was a bug that they were missing: if
make_iterator is called twice with different values of these, only the
first set has effect (because the state class is only registered once).
There is still a potential issue in that the *values* of the extra
arguments are latched on the first call, but since most policies are
empty classes this should be even less common.

* Add some remove_cv_t to appease clang-tidy

* Make iterator_access and friends take reference

For some reason I'd accidentally made it take a const value, which
caused some issues with third-party packages.

* Another attempt to remove remove_cv_t from iterators

Some of the return types were const (non-reference) types because of the
pecularities of decltype: `decltype((*it).first)` is the *declared* type
of the member of the pair, rather than the type of the expression. So if
the reference type of the iterator is `pair<const int, int> &`, then the
decltype is `const int`. Wrapping an extra set of parentheses to form
`decltype(((*it).first))` would instead give `const int &`.

This means that the existing make_key_iterator actually returns by value
from `__next__`, rather than by reference. Since for mapping types, keys
are always const, this probably hasn't been noticed, but it will affect
make_value_iterator if the Python code tries to mutate the returned
objects. I've changed things to use double parentheses so that
make_iterator, make_key_iterator and make_value_iterator should now all
return the reference type of the iterator. I'll still need to add a test
for that; for now I'm just checking whether I can keep Clang-Tidy happy.

* Add back some NOLINTNEXTLINE to appease Clang-Tidy

This is favoured over using remove_cv_t because in some cases a const
value return type is deliberate (particularly for Eigen).

* Add a unit test for iterator referencing

Ensure that make_iterator, make_key_iterator and make_value_iterator
return references to the container elements, rather than copies. The
test for make_key_iterator fails to compile on master, which gives me
confidence that this branch has fixed it.

* Make the iterator_access etc operator() const

I'm actually a little surprised it compiled at all given that the
operator() is called on a temporary, but I don't claim to fully
understand all the different value types in C++11.

* Attempt to work around compiler bugs

https://godbolt.org/ shows an example where ICC gets the wrong result
for a decltype used as the default for a template argument, and CI also
showed problems with PGI. This is a shot in the dark to see if it fixes
things.

* Make a test constructor explicit (Clang-Tidy)

* Fix unit test on GCC 4.8.5

It seems to require the arguments to the std::pair constructor to be
implicitly convertible to the types in the pair, rather than just
requiring is_constructible.

* Remove DOXYGEN_SHOULD_SKIP_THIS guards

Now that a complex decltype expression has been replaced by a simpler
nested type, I'm hoping Doxygen will be able to build it without issues.

* Add comment to explain iterator_state template params
2021-09-21 13:37:19 -04:00