Veetaha
commented
1 year ago The problem occurs because the code tries to look up the definition of the item in HIR, but that item comes from a foreign crate.
When the TraitRef's ItemId is created here https://github.com/rust-marker/marker/blob/73835de0a82ebd33b959df200f66e5a3d7bf007a/marker_rustc_driver/src/conversion/marker/common.rs#L414
The type of the ID that is transmuted into ItemId is rustc_span::def_id::DefId. But when the ctx.ast().item() is called the ItemId is converted into rustc_hir::hir::ItemId. You may notice that the method in the snippet below doesn't use the layout.krate field at all. I guess it assumes that this method is always called with local items (of the current crate).
https://github.com/rust-marker/marker/blob/73835de0a82ebd33b959df200f66e5a3d7bf007a/marker_rustc_driver/src/conversion/rustc/common.rs#L73-L82
So this results in an invalid rustc_hir::hir::ItemId. You'll get a panic even if you try to debug-print this ID.
I'm not sure what the best solution here should be. Maybe the to_item_id(ItemId) -> hir::ItemId method should check if layout.krate is not a local crate. I suppose there is a special sentinel value for krate that identifies it as the current crate. Then if the given item is not from the current crate it should return None.
But how could users query the info about which trait is implemented? Maybe if there was at least the path to the implemented trait in the TraitRef that would allow to check the syntactic path to the trait.
xFrednet
Summary
I've been trying to implement a lint that prohibits implementing
Into/TryIntotraits directly and I've run into multiple issues with it. This is one of them. However, I suppose even if this is fixedctx.ast().item()will returnNonebecause the trait is outside of the compiled crate? Then how could I check which trait theimplitem tries to implement?Btw. if I output the impl item of the
Intotrait impl specified in the reproducer below I get this. You can see that there is no implemented trait identifier anywhere in the data. This is bummerDetails
```rust impl_ = ImplItem { data: CommonItemData { id: ItemId(..), span: SpanId(..), vis: Visibility {{ /* WIP: See rust-marker/marker#26 */}}, ident: Ident { name: "", span: crates/scratch/src/main.rs:1:1 - 1:1, }, }, is_unsafe: false, is_negated: true, trait_ref: Some( TraitRef { item_id: ItemId(..), generics: GenericArgs { args: [ Ty( TyArg { ty: Tuple( TupleTy { data: CommonSynTyData { _lifetime: PhantomData<&()>, span: SpanId(..), }, types: [], }, ), }, ), ], }, }, ), generics: GenericParams { params: [], clauses: [], }, ty: Path( PathTy { data: CommonSynTyData { _lifetime: PhantomData<&()>, span: SpanId(..), }, path: AstQPath { self_ty: None, path_ty: None, path: AstPath { segments: [ AstPathSegment { ident: Ident { name: "Foo", span: crates/scratch/src/main.rs:3:19 - 3:22, }, generics: GenericArgs { args: [], }, }, ], }, target: Item( ItemId(..), ), }, }, ), items: [ Fn( FnItem { data: CommonItemData { id: ItemId(..), span: SpanId(..), vis: Visibility {{ /* WIP: See rust-marker/marker#26 */}}, ident: Ident { name: "into", span: crates/scratch/src/main.rs:4:8 - 4:12, }, }, generics: GenericParams { params: [], clauses: [], }, constness: NotConst, syncness: Sync, safety: Safe, is_extern: false, has_self: true, abi: Default, params: [ FnParam { span: SpanId(..), pat: Ident( IdentPat { data: CommonPatData { _lifetime: PhantomData<&()>, span: SpanId(..), }, name: SymbolId(..), var: VarId(..), mutability: Unmut, is_ref: false, binding_pat: None, }, ), ty: Path( PathTy { data: CommonSynTyData { _lifetime: PhantomData<&()>, span: SpanId(..), }, path: AstQPath { self_ty: None, path_ty: None, path: AstPath { segments: [ AstPathSegment { ident: Ident { name: "Self", span: crates/scratch/src/main.rs:1:1 - 1:1, }, generics: GenericArgs { args: [], }, }, ], }, target: SelfTy( ItemId(..), ), }, }, ), }, ], return_ty: None, body_id: Some( BodyId(..), ), }, .., ), ], } ```Reproducer
[derive(Default)]
struct MyLintPass {} marker_api::export_lint_pass!(MyLintPass);
marker_api::declare_lint! { /// # What it does /// Breaks marker. MY_LINT, Deny, }
impl LintPass for MyLintPass { fn info(&self) -> LintPassInfo { LintPassInfoBuilder::new(Box::new([MY_LINT])).build() }
}
cargo markerVersion
Logs