During merge, HEAD's regex pattern was kept, but master's version is preferred.
The order of ` ` and `\|` in the character class is arbitrary. Keep master's order
(already fixed in PR pybind#5891; sorry I missed looking back here when working on 5891).

…r PEP 484 compatibility). (#5879)

* init

Signed-off-by: Michael Carlstrom <[email protected]>

* Add constexpr to is_floating_point check

This is known at compile time so it can be constexpr

* Allow noconvert float to accept int

* Update noconvert documentation

* Allow noconvert complex to accept int and float

* Add complex strict test

* style: pre-commit fixes

* Update unit tests so int, becomes double.

* style: pre-commit fixes

* remove if (constexpr)

Signed-off-by: Michael Carlstrom <[email protected]>

* fix spelling error

* bump order in #else

* Switch order in c++11 only section

Signed-off-by: Michael Carlstrom <[email protected]>

* ci: trigger build

* ci: trigger build

* Allow casting from float to int

The int type caster allows anything that implements __int__ with explicit exception of the python float. I can't see any reason for this.
This modifies the int casting behaviour to accept a float.
If the argument is marked as noconvert() it will only accept int.

* tests for py::float into int

* Update complex_cast tests

* Add SupportsIndex to int and float

* style: pre-commit fixes

* fix assert

* Update docs to mention other conversions

* fix pypy __index__ problems

* style: pre-commit fixes

* extract out PyLong_AsLong __index__ deprecation

Signed-off-by: Michael Carlstrom <[email protected]>

* style: pre-commit fixes

* Add back env.deprecated_call

Signed-off-by: Michael Carlstrom <[email protected]>

* remove note

Signed-off-by: Michael Carlstrom <[email protected]>

* remove untrue comment

Signed-off-by: Michael Carlstrom <[email protected]>

* fix noconvert_args

Signed-off-by: Michael Carlstrom <[email protected]>

* resolve error

Signed-off-by: Michael Carlstrom <[email protected]>

* Add comment

Signed-off-by: Michael Carlstrom <[email protected]>

* [skip ci]

tests: Add overload resolution test for float/int breaking change

Add test_overload_resolution_float_int() to explicitly test the breaking
change where int arguments now match float overloads when registered first.

The existing tests verify conversion behavior (int -> float, int/float -> complex)
but do not test overload resolution when both float and int overloads exist.
This test fills that gap by:

- Testing that float overload registered before int overload matches int(42)
- Testing strict mode (noconvert) overload resolution breaking change
- Testing complex overload resolution with int/float/complex overloads
- Documenting the breaking change explicitly

This complements existing tests which verify 'can it convert?' by testing
'which overload wins when multiple can convert?'

* Add test to verify that custom __index__ objects (not PyLong) work correctly with complex conversion. These should be consistent across CPython, PyPy, and GraalPy.

* Improve comment clarity for PyPy __index__ handling

Replace cryptic 'So: PYBIND11_INDEX_CHECK(src.ptr())' comment with
clearer explanation of the logic:

- Explains that we need to call PyNumber_Index explicitly on PyPy
  for non-PyLong objects
- Clarifies the relationship to the outer condition: when convert
  is false, we only reach this point if PYBIND11_INDEX_CHECK passed
  above

This makes the code more maintainable and easier to understand
during review.

* Undo inconsequential change to regex in test_enum.py

During merge, HEAD's regex pattern was kept, but master's version is preferred.
The order of ` ` and `\|` in the character class is arbitrary. Keep master's order
(already fixed in PR #5891; sorry I missed looking back here when working on 5891).

* test_methods_and_attributes.py: Restore existing `m.overload_order(1.1)` call and clearly explain the behavior change.

* Reject float → int conversion even in convert mode

Enabling implicit float → int conversion in convert mode causes
silent truncation (e.g., 1.9 → 1). This is dangerous because:

1. It's implicit - users don't expect truncation when calling functions
2. It's silent - no warning or error
3. It can hide bugs - precision loss is hard to detect

This change restores the explicit rejection of PyFloat_Check for integer
casters, even in convert mode. This is more in line with Python's behavior
where int(1.9) must be explicit.

Note that the int → float conversion in noconvert mode is preserved,
as that's a safe widening conversion.

* Revert test changes that sidestepped implicit float→int conversion

This reverts all test modifications that were made to accommodate
implicit float→int conversion in convert mode. With the production
code change that explicitly rejects float→int conversion even in
convert mode, these test workarounds are no longer needed.

Changes reverted:
- test_builtin_casters.py: Restored cant_convert(3.14159) and
  np.float32 conversion with deprecated_call wrapper
- test_custom_type_casters.py: Restored TypeError expectation for
  m.ints_preferred(4.0)
- test_methods_and_attributes.py: Restored TypeError expectation
  for m.overload_order(1.1)
- test_stl.py: Restored float literals (2.0) that were replaced with
  strings to avoid conversion
- test_factory_constructors.py: Restored original constructor calls
  that were modified to avoid float→int conversion

Also removes the unused avoid_PyLong_AsLong_deprecation fixture
and related TypeVar imports, as all uses were removed.

* Replace env.deprecated_call() with pytest.deprecated_call()

The env.deprecated_call() function was removed, but two test cases
still reference it. Replace with pytest.deprecated_call(), which is
the standard pytest context manager for handling deprecation warnings.

Since we already require pytest>=6 (see tests/requirements.txt), the
compatibility function is obsolete and pytest.deprecated_call() is
available.

* Update test expectations for swapped NoisyAlloc overloads

PR 5879 swapped the order of NoisyAlloc constructor overloads:
- (int i, double) is now placement new (comes first)
- (double d, double) is now factory pointer (comes second)

This swap is necessary because pybind11 tries overloads in order
until one matches. With int → float conversion now allowed:

- create_and_destroy(4, 0.5): Without the swap, (double d, double)
  would match first (since int → double conversion is allowed),
  bypassing the more specific (int i, double) overload. With the
  swap, (int i, double) matches first (exact match), which is
  correct.

- create_and_destroy(3.5, 4.5): (int i, double) fails (float → int
  is rejected), then (double d, double) matches, which is correct.

The swap ensures exact int matches are preferred over double matches
when an int is provided, which is the expected overload resolution
behavior.

Update the test expectations to match the new overload resolution
order.

* Resolve clang-tidy error:

/__w/pybind11/pybind11/include/pybind11/cast.h:253:46: error: repeated branch body in conditional chain [bugprone-branch-clone,-warnings-as-errors]
  253 |         } else if (PyFloat_Check(src.ptr())) {
      |                                              ^
/__w/pybind11/pybind11/include/pybind11/cast.h:258:10: note: end of the original
  258 |         } else if (convert || PYBIND11_LONG_CHECK(src.ptr()) || PYBIND11_INDEX_CHECK(src.ptr())) {
      |          ^
/__w/pybind11/pybind11/include/pybind11/cast.h:283:16: note: clone 1 starts here
  283 |         } else {
      |                ^

* Add test coverage for __index__ and __int__ edge cases: incorrectly returning float

These tests ensure that:
- Invalid return types (floats) are properly rejected
- The fallback from __index__ to __int__ works correctly in convert mode
- noconvert mode correctly prevents fallback when __index__ fails

* Minor comment-only changes: add PR number, for easy future reference

* Ensure we are not leaking a Python error is something is wrong elsewhere (e.g. UB, or bug in Python beta testing).

See also: #5879 (comment)

* [skip ci] Bump PYBIND11_INTERNALS_VERSION to 12 (for PRs 5879, 5887, 5960)

---------

Signed-off-by: Michael Carlstrom <[email protected]>
Co-authored-by: gentlegiantJGC <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Ralf W. Grosse-Kunstleve <[email protected]>