[PATCH 0/4] rust: add `FromPrimitive` support

[Jesung Yang]

This patch series introduces a new `FromPrimitive` trait along with its
corresponding derive macro.

A few enhancements were made to the custom `quote!` macro to write the
derive macro. These include support for additional punctuation tokens
and a fix for an unused variable warning when quoting simple forms.
Detailed information about these enhancements is provided in the
relevant patches.

While cleaning up the implementations, I came across an alternative
form of the `FromPrimitive` trait that might better suit the current
use case. Since types that implement this trait may often rely on just
one `from_*` method, the following design could be a simpler fit:

    trait FromPrimitive: Sized {
        type Primitive;

        fn from_bool(b: bool) -> Option<Self>
        where
            <Self as FromPrimitive>::Primitive: From<bool>,
        {
            Self::from_primitive(b.into())
        }

        fn from_primitive(n: Self::Primitive) -> Option<Self>;
    }

This is just a thought and not something I feel strongly about, but I
wanted to share it in case others find the idea useful. Feedback or
suggestions are very welcome.

The original discussion of FromPrimitive can be found on Zulip [1].

[1] https://rust-for-linux.zulipchat.com/#narrow/channel/288089/topic/x/near/524427350

Jesung Yang (4):
  rust: introduce `FromPrimitive` trait
  rust: macros: extend custom `quote!` macro
  rust: macros: prefix variable `span` with underscore
  rust: macros: add derive macro for `FromPrimitive`

 rust/kernel/convert.rs | 154 +++++++++++++++++++++++++++++
 rust/kernel/lib.rs     |   1 +
 rust/macros/convert.rs | 217 +++++++++++++++++++++++++++++++++++++++++
 rust/macros/lib.rs     |  71 ++++++++++++++
 rust/macros/quote.rs   |  46 ++++++++-
 5 files changed, 487 insertions(+), 2 deletions(-)
 create mode 100644 rust/kernel/convert.rs
 create mode 100644 rust/macros/convert.rs


base-commit: dc35ddcf97e99b18559d0855071030e664aae44d
-- 
2.39.5