5 commits

Author	SHA1	Message	Date
Martin von Zweigbergk	5ce5022ee9	cargo: mark the jj-lib-proc-macros crate for publish ... I don't think we can publish a new version of the other crates without publishing `jj-lib-proc-macros`.	2024-03-06 20:35:38 -08:00
Evan Mesterhazy	79518eafce	Output better error messages when deriving ContentHash for an enum fails ... Consider this code: ``` struct NoContentHash {} #[derive(ContentHash)] enum Hashable { NoCanHash(NoContentHash), Empty, } ``` Before this commit, it generates an error like this: ``` error[E0277]: the trait bound `NoContentHash: ContentHash` is not satisfied --> lib/src/content_hash.rs:150:10 | 150 | #[derive(ContentHash)] | ^^^^^^^^^^^ the trait `ContentHash` is not implemented for `NoContentHash` 151 | enum Hashable { 152 | NoCanHash(NoContentHash), | --------- required by a bound introduced by this call | = help: the following other types implement trait `ContentHash`: bool i32 i64 u8 u32 u64 std::collections::HashMap<K, V> BTreeMap<K, V> and 35 others For more information about this error, try `rustc --explain E0277`. ``` After this commit, it generates a better error message: ``` error[E0277]: the trait bound `NoContentHash: ContentHash` is not satisfied --> lib/src/content_hash.rs:152:15 | 152 | NoCanHash(NoContentHash), | ^^^^^^^^^^^^^ the trait `ContentHash` is not implemented for `NoContentHash` | = help: the following other types implement trait `ContentHash`: bool i32 i64 u8 u32 u64 std::collections::HashMap<K, V> BTreeMap<K, V> and 35 others For more information about this error, try `rustc --explain E0277`. error: could not compile `jj-lib` (lib) due to 1 previous error ``` It also works for enum variants with named fields: ``` error[E0277]: the trait bound `NoContentHash: ContentHash` is not satisfied --> lib/src/content_hash.rs:152:23 | 152 | NoCanHash { named: NoContentHash }, | ^^^^^^^^^^^^^ the trait `ContentHash` is not implemented for `NoContentHash` | = help: the following other types implement trait `ContentHash`: bool i32 i64 u8 u32 u64 std::collections::HashMap<K, V> BTreeMap<K, V> and 35 others For more information about this error, try `rustc --explain E0277`. ```	2024-02-20 16:29:25 -05:00
Evan Mesterhazy	966a5505e2	Add support for deriving ContentHash for Enums ... Here's an example of what the derived output looks like for an enum: ```rust pub enum TreeValue { File { id: FileId, executable: bool }, Symlink(SymlinkId), Tree(TreeId), GitSubmodule(CommitId), Conflict(ConflictId), } #[automatically_derived] impl ::jj_lib::content_hash::ContentHash for TreeValue { fn hash(&self, state: &mut impl digest::Update) { match self { Self::File { id, executable } => { state.update(&0u32.to_le_bytes()); ::jj_lib::content_hash::ContentHash::hash(id, state); ::jj_lib::content_hash::ContentHash::hash(executable, state); } Self::Symlink(field_0) => { state.update(&1u32.to_le_bytes()); ::jj_lib::content_hash::ContentHash::hash(field_0, state); } Self::Tree(field_0) => { state.update(&2u32.to_le_bytes()); ::jj_lib::content_hash::ContentHash::hash(field_0, state); } Self::GitSubmodule(field_0) => { state.update(&3u32.to_le_bytes()); ::jj_lib::content_hash::ContentHash::hash(field_0, state); } Self::Conflict(field_0) => { state.update(&4u32.to_le_bytes()); ::jj_lib::content_hash::ContentHash::hash(field_0, state); } } } } ``` #3054	2024-02-20 12:59:35 -05:00
Evan Mesterhazy	8e1a6c708f	Add support for generics to #[derive(ContentHash)] ... #3054	2024-02-20 12:48:25 -05:00
Evan Mesterhazy	965d6ce4e4	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	2024-02-20 11:29:05 -05:00