lang: add anchor_lang::pubkey macro for declaring const Pubkey values

[mina86]

anchor_lang::solana_program::pubkey macro doesn’t work because it
expands to code using ::solana_program::pubkey::Pubkey type (note
leading ::). Since programs using anchor-lang crate usually don’t
include solana-program dependency, that symbol ends up unresolved.

Introduce anchor_lang::pubkey macro which accesses solana_program via
anchor_lang instead. This is analogous to declare_id macro which also
had to be repeated in anchor-lang.

[vercel]

@mina86 is attempting to deploy a commit to the coral-xyz Team on Vercel.

A member of the Team first needs to authorize it.

[acheroncrypto]

Yeah, there is actually a very old issue about this here: solana-labs/solana#24303

I think this could get fixed upstream + us exporting solana_program from prelude, but I also don't see any problem getting this in to Anchor.

Before we merge, could you note this feature in the CHANGELOG?

[mina86]

Done.

Yes, if Solana dropped :: prefix, this as well as declare_id definitions wouldn’t be necessary in Anchor. Looks like they don’t have appetite for that though.

[acheroncrypto]

declare_id would still be necessary as we override it for idl-build feature:

anchor/lang/attribute/account/src/lib.rs

Lines 437 to 444 in cdf2559

	#[cfg(feature = "idl-build")]
	{
	let idl_print = anchor_syn::idl::gen_idl_print_fn_address(address);
	return proc_macro::TokenStream::from(quote! {
	#ret
	#idl_print
	});
	}

Thanks!