jj/lib/proc-macros/Cargo.toml

[package]
name = "jj-lib-proc-macros"
publish = false

version = { workspace = true }
edition = { workspace = true }
license = { workspace = true }

[lib]
proc-macro = true

[dependencies]
proc-macro2 = { workspace = true }
quote = { workspace = true }
syn = { workspace = true }
Implement a procedural macro to derive the ContentHash trait for structs This is a no-op in terms of function, but provides a nicer way to derive the ContentHash trait for structs using the `#[derive(ContentHash)]` syntax used for other traits such as `Debug`. This commit only adds the macro. A subsequent commit will replace uses of `content_hash!{}` with `#[derive(ContentHash)]`. The new macro generates nice error messages, just like the old macro: ``` error[E0277]: the trait bound `NotImplemented: content_hash::ContentHash` is not satisfied --> lib/src/content_hash.rs:265:16 \| 265 \| z: NotImplemented, \| ^^^^^^^^^^^^^^ the trait `content_hash::ContentHash` is not implemented for `NotImplemented` \| = help: the following other types implement trait `content_hash::ContentHash`: bool i32 i64 u8 u32 u64 std::collections::HashMap<K, V> BTreeMap<K, V> and 38 others ``` This commit does two things to make proc macros re-exported by jj_lib useable by deps: 1. jj_lib needs to be able refer to itself as `jj_lib` which it does by adding an `extern crate self as jj_lib` declaration. 2. jj_lib::content_hash needs to re-export the `digest::Update` type so that users of jj_lib can use the `#[derive(ContentHash)]` proc macro without directly depending on the digest crate. This is done by re-exporting it as `DigestUpdate`. #3054 2024-02-13 23:10:30 +00:00			`[package]`
			`name = "jj-lib-proc-macros"`
			`publish = false`

			`version = { workspace = true }`
			`edition = { workspace = true }`
			`license = { workspace = true }`

			`[lib]`
			`proc-macro = true`

			`[dependencies]`
			`proc-macro2 = { workspace = true }`
			`quote = { workspace = true }`
			`syn = { workspace = true }`