[PATCH v2 0/3] rust: const_eval: add a mechanism to do const trait calls

[Gary Guo <gary@garyguo.net>]

Add a mechanism to perform const trait method calls, with the same type
inference capabilities. This would only work for concrete types (not inside
generic functions).

As an example, convert `as_char_ptr_in_const_context`, so instead of

    kernel::str::as_char_ptr_in_const_context(c_str)

one may write

    const_call!(c_str.as_char_ptr())

instead.

Signed-off-by: Gary Guo <gary@garyguo.net>
---
Changes in v2:
- Split from `cv!()` alt series, and become a general infra instead.
- Link to v1: https://patch.msgid.link/20260828-cv-v1-0-694a695ff17f@garyguo.net

---
Gary Guo (3):
      rust: const_eval: add `#[const_eval_only]` attribute
      rust: const_eval: allow const trait method invocation in some contexts
      rust: str: convert `as_char_ptr` to work with `const_call!`

 rust/build_error.rs       |   7 +++
 rust/kernel/configfs.rs   |   2 +-
 rust/kernel/const_eval.rs | 115 ++++++++++++++++++++++++++++++++++++++++++++++
 rust/kernel/device_id.rs  |   4 ++
 rust/kernel/drm/device.rs |   4 +-
 rust/kernel/drm/ioctl.rs  |   4 +-
 rust/kernel/kunit.rs      |   6 +--
 rust/kernel/lib.rs        |   1 +
 rust/kernel/miscdevice.rs |   2 +-
 rust/kernel/net/phy.rs    |   2 +-
 rust/kernel/prelude.rs    |   1 +
 rust/kernel/str.rs        |  15 +++---
 rust/macros/const_eval.rs |  51 ++++++++++++++++++++
 rust/macros/lib.rs        |  39 ++++++++++++++++
 rust/macros/module.rs     |   4 +-
 15 files changed, 237 insertions(+), 20 deletions(-)
---
base-commit: 89c07d98716a13454ec3fd9f97689e812cc71bd4
change-id: 20260828-cv-acaf3400d16c

Best regards,
--  
Gary Guo <gary@garyguo.net>