x509-cert: draft: TbsCertificateInner generic over DerMemory trait

[dishmaker]

Im stuck on invariant lifetime.

lifetime may not live long enough
requirement occurs because of the type `CertificateInner<'_, AllocDerMemory, P>`, which makes the generic argument `'_` invariant
the struct `CertificateInner<'m, MEM, P>` is invariant over the parameter `'m`
see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance

anchor.rs(94, 6): lifetime `'__der_lifetime` defined here

Adding der::Cow looks easier, i think 🤔

[tarcieri]

I'm not sure what you're trying to accomplish with this

[dishmaker]

I want to make Ref and Owned types from TbsCertificateInner.

formats/pkcs8/src/private_key_info.rs

Lines 373 to 378 in 907a76a

	/// [`PrivateKeyInfo`] with [`AnyRef`] algorithm parameters, and `&[u8]` key.
	pub type PrivateKeyInfoRef<'a> = PrivateKeyInfo<AnyRef<'a>, OctetStringRef<'a>, BitStringRef<'a>>;
	/// [`PrivateKeyInfo`] with [`Any`] algorithm parameters, and `Box<[u8]>` key.
	#[cfg(feature = "alloc")]
	pub type PrivateKeyInfoOwned = PrivateKeyInfo<Any, OctetString, BitString>;

[tarcieri]

It would probably be good to flesh out a design in #1603.

Note that elsewhere we have avoided adding lifetimes except for the reference types, which can be done with generic parameters (as opposed to what you're trying to do with 'static in this PR)