Add more const constructors and various convenience functions to Number for generic conversions (#47)

* Add more const constructors and various convenience functions to Number for generic conversions

In particular:
- new_u8, new_u16, ..., new_u128 which allow creating an arbitrary int without type conversion,
  e.g. `u5::new_u32(123)`
- new_() which allows any Number argument to be passed through generics
- as_() which easily converts any Number to another
- as_u8(), as_u16() for more control (and to implement the others)

* Fix compile errors

* Fix some range checking bugs

* Clarify compile time asserts, give them cleaner error messages

First step in making .into() more usable

* Improve comments; work in new assert_unchecked in the various getters

* Add as_usize()

* Add inline_const to const_convert_and_const_trait_impl (which is needed only for the old compiler)

* Update changelog, bump version

* Incorporate naming feedback

* Fix test names

---------

Co-authored-by: Daniel Lehmann <[email protected]>

Author: danlehmann

CHANGELOG.md

@@ -1,11 +1,19 @@
 # Changelog
 
-## arbitrary-int 1.2.8
+## arbitrary-int 1.3.0
 
 ### Added
 
 - New optional feature `hint`, which tells the compiler that the returned `value()` can't exceed a maximum value. This
   allows the compiler to optimize faster code at the expense of unsafe code within arbitrary-int itself.
+- Various new const constructors: `new_u8`, `new_u16`, ..., `new_u128` which allow creating an arbitrary int without
+  type conversion, e.g. `u5::new_u32(i)` (where i is e.g. u32). This is shorter than writing
+  `u5::new(i.try_into().unwrap())`,
+  and combines two possible panic paths into one. Also, unlike `try_into().unwrap()`, the new constructors are usable in
+  const contexts.
+- For non-const contexts, `new_()` allows any Number argument to be passed through generics.
+- `as_()` easily converts any Number to another. `as_u8()`, `as_u16()` for more control (and to implement the others).
+- New optional feature `borsh` to support binary serialization using the borsh crate.
 
 ## arbitrary-int 1.2.7
 

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "arbitrary-int"
-version = "1.2.7"
+version = "1.3.0"
 edition = "2021"
 authors = ["Daniel Lehmann <[email protected]>"]
 description = "Modern and lightweight implementation of u2, u3, u4, ..., u127."
@@ -15,7 +15,9 @@ std = []
 
 # Supports const trait implementation through const_convert and const_trait_impl. Support for those was removed
 # from more recent Rust nightlies, so this feature requires an older Rust compiler
-# (2023-04-20 is broken, 2022-11-23 works. The exact day is somewhere inbetween)
+# (2023-04-20 is broken, 2022-11-23 works. The exact day is somewhere inbetween).
+# As of 12/2/2024, this also uses inline_const. This has been stabilized but is required for current code to work
+# on the old compiler.
 const_convert_and_const_trait_impl = []
 
 # core::fmt::Step is currently unstable and is available on nightly behind a feature gate