Make blocks with encoding easier to use #651

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1. madsmtm

   added

   enhancementNew feature or requestNew feature or request

   A-block2Affects the `block2` crateAffects the `block2` crate

   on Sep 17, 2024
2. madsmtm commented on Sep 8, 2025

   

   madsmtm

   on Sep 8, 2025

   Last edited by madsmtm

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   I recall having a quick look at the amount of block signatures that Apple uses a month back, and it was unfortunately several hundred, which is probably too large a compile-time hit :/.

   So we'll probably have to wait for generic const expressions (see 050b502 for a test with that).

   👍React with 👍1Reacted by Paul Mabileau
3. madsmtm commented on Mar 4, 2026

   

   madsmtm

   on Mar 4, 2026

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   An idea from #70: Since we can generate encoding strings in const, just not generically, maybe add something like:

   // block2
   pub fn block_encoding_str_len(args: &[Encoding], ret: &Encoding) -> usize { ... }
   pub fn block_encoding_str_array<const LEN: usize>(args: &[Encoding], ret: &Encoding) -> [LEN; u8] { ... }
   
   // Usage
   struct MyBlockEncoding;
   // SAFETY: The encoding is correct.
   unsafe impl ManualBlockEncoding for MyBlockEncoding {
       type Arguments = (*mut NSError,);
       type Return = i32;
       const ENCODING_CSTR: &'static CStr = {
           const LEN: usize = block_encoding_str_len(<(*mut NSError,)>::ENCODINGS, i32::ENCODING_RETURN);
           let arr = block_encoding_str_array::<LEN>(<(*mut NSError,)>::ENCODINGS, i32::ENCODING_RETURN);
           CStr::from_bytes_with_nul(&arr).unwrap()
       };
   }

   And maybe wrap it in a macro like:

   block2::manual_encoding!(fn MyBlockEncoding(error: *mut NSError) -> i32);

   👍React with 👍1Reacted by Paul Mabileau