Implement selector_id!, selector_bytes! and blake2x256! macros

[Robbepop]

Inspired by the METIS library utility macros this PR adds those macros (different implementation and API) to ink! as built-ins.

Link: /~https://github.com/patractlabs/metis/blob/main/crates/lang/macro/src/lib.rs

Adds the following proc. macros to ink_lang_macro crate that are exposed from ink_lang:

• selector_id!: Takes a string or byte string literal as input and computes the selector ID of type u32.
• selector_bytes!: Takes a string or byte string literal as input and computes the selector bytes of type [u8; 4].
• blake2x256!: Takes a string or byte string literal as input and computes the BLAKE2b 256-bit hash of type [u8; 32].

ToDo List

• Write UI tests for ...
  • selector_id!
  • selector_bytes!
  • blake2x256!

[codecov-commenter]

Codecov Report

Merging #947 (a4abc4d) into master (7c19f63) will decrease coverage by 1.12%.
The diff coverage is 88.39%.

@@            Coverage Diff             @@
##           master     #947      +/-   ##
==========================================
- Coverage   82.86%   81.73%   -1.13%     
==========================================
  Files         177      190      +13     
  Lines        8055     8165     +110     
==========================================
- Hits         6675     6674       -1     
- Misses       1380     1491     +111     

Impacted Files	Coverage Δ
crates/lang/codegen/src/generator/mod.rs	100.00% <ø> (ø)
crates/lang/codegen/src/lib.rs	100.00% <ø> (ø)
crates/lang/ir/src/ir/selector.rs	74.28% <73.68%> (-0.72%)	⬇️
crates/lang/ir/src/ir/blake2.rs	79.16% <75.00%> (-20.84%)	⬇️
crates/lang/macro/src/blake2b.rs	85.71% <85.71%> (ø)
crates/lang/macro/src/selector.rs	85.71% <85.71%> (ø)
crates/lang/codegen/src/generator/blake2b.rs	100.00% <100.00%> (ø)
crates/lang/codegen/src/generator/selector.rs	100.00% <100.00%> (ø)
crates/lang/macro/src/lib.rs	100.00% <100.00%> (ø)
...ng/macro/tests/ui/blake2b/pass/bytestring_input.rs	100.00% <100.00%> (ø)
... and 22 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 7c19f63...a4abc4d. Read the comment docs.

[xgreenx]

Maybe will be useful to add a method that will return 'u32' from the hash. It is possible to get from the selector by 'into_be_u32' method. But it is not clear for a new developer:)

[Robbepop]

Maybe will be useful to add a method that will return 'u32' from the hash. It is possible to get from the selector by 'into_be_u32' method. But it is not clear for a new developer:)

From what I understood this is equal to selector_id! and therefore duplicate API. I would like to keep the API minimal.
I think your stated problem should be tackled with proper documentation where necessary.

[xgreenx]

Oh, I see, you've already returned a u32. I thought that it is Selector, but it is u32 or [u8; 4] . Then cool!:)

[xgreenx]

Maybe selector_u32 is more clear than selector_id?:)

[Robbepop]

Maybe selector_u32 is more clear than selector_id?:)

Maybe but I thought that selector_id is a high level concept as is Selector in itself.
So calling it selector_u32! would be a half baked solution.
The opposite would be to name it blake2x256_first4_as_u32 but that is way too concrete.

[Robbepop]

Added all the UI tests for the new macros.
Ready for review! :)

[xgreenx]

What do you think about selector_id_u32 and selector_id_bytes?:D - Joke:)

[ascjones]

LGTM