feat: Diagnose some orphan trait impl cases

crates/hir-def/src/body/pretty.rs

@@ -54,7 +54,7 @@ pub(super) fn print_body_hir(db: &dyn DefDatabase, body: &Body, owner: DefWithBo
     let mut p = Printer { db, body, buf: header, indent_level: 0, needs_indent: false };
     if let DefWithBodyId::FunctionId(it) = owner {
         p.buf.push('(');
-        body.params.iter().zip(&db.function_data(it).params).for_each(|(&param, ty)| {
+        body.params.iter().zip(db.function_data(it).params.iter()).for_each(|(&param, ty)| {
             p.print_pat(param);
             p.buf.push(':');
             p.print_type_ref(ty);

crates/hir-def/src/data.rs

@@ -34,7 +34,7 @@ use crate::{
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct FunctionData {
     pub name: Name,
-    pub params: Vec<Interned<TypeRef>>,
+    pub params: Box<[Interned<TypeRef>]>,
     pub ret_type: Interned<TypeRef>,
     pub attrs: Attrs,
     pub visibility: RawVisibility,
@@ -177,7 +177,7 @@ pub struct TypeAliasData {
     pub rustc_has_incoherent_inherent_impls: bool,
     pub rustc_allow_incoherent_impl: bool,
     /// Bounds restricting the type alias itself (eg. `type Ty: Bound;` in a trait or impl).
-    pub bounds: Vec<Interned<TypeBound>>,
+    pub bounds: Box<[Interned<TypeBound>]>,
 }
 
 impl TypeAliasData {
@@ -210,7 +210,7 @@ impl TypeAliasData {
             is_extern: matches!(loc.container, ItemContainerId::ExternBlockId(_)),
             rustc_has_incoherent_inherent_impls,
             rustc_allow_incoherent_impl,
-            bounds: typ.bounds.to_vec(),
+            bounds: typ.bounds.clone(),
         })
     }
 }

crates/hir-def/src/generics.rs

@@ -227,7 +227,7 @@ impl GenericParams {
                 let mut expander = Lazy::new(|| {
                     (module.def_map(db), Expander::new(db, loc.source(db).file_id, module))
                 });
-                for param in &func_data.params {
+                for param in func_data.params.iter() {
                     generic_params.fill_implicit_impl_trait_args(db, &mut expander, param);
                 }
 

crates/hir-def/src/item_tree/lower.rs

@@ -396,14 +396,7 @@ impl<'a> Ctx<'a> {
         let bounds = self.lower_type_bounds(type_alias);
         let generic_params = self.lower_generic_params(HasImplicitSelf::No, type_alias);
         let ast_id = self.source_ast_id_map.ast_id(type_alias);
-        let res = TypeAlias {
-            name,
-            visibility,
-            bounds: bounds.into_boxed_slice(),
-            generic_params,
-            type_ref,
-            ast_id,
-        };
+        let res = TypeAlias { name, visibility, bounds, generic_params, type_ref, ast_id };
         Some(id(self.data().type_aliases.alloc(res)))
     }
 
@@ -637,13 +630,13 @@ impl<'a> Ctx<'a> {
         Interned::new(generics)
     }
 
-    fn lower_type_bounds(&mut self, node: &dyn ast::HasTypeBounds) -> Vec<Interned<TypeBound>> {
+    fn lower_type_bounds(&mut self, node: &dyn ast::HasTypeBounds) -> Box<[Interned<TypeBound>]> {
         match node.type_bound_list() {
             Some(bound_list) => bound_list
                 .bounds()
                 .map(|it| Interned::new(TypeBound::from_ast(&self.body_ctx, it)))
                 .collect(),
-            None => Vec::new(),
+            None => Box::default(),
         }
     }
 

crates/hir-ty/src/db.rs

@@ -20,8 +20,8 @@ use crate::{
     method_resolution::{InherentImpls, TraitImpls, TyFingerprint},
     mir::{BorrowckResult, MirBody, MirLowerError},
     Binders, CallableDefId, ClosureId, Const, FnDefId, GenericArg, ImplTraitId, InferenceResult,
-    Interner, PolyFnSig, QuantifiedWhereClause, ReturnTypeImplTraits, Substitution, TraitRef, Ty,
-    TyDefId, ValueTyDefId,
+    Interner, PolyFnSig, QuantifiedWhereClause, ReturnTypeImplTraits, Substitution,
+    TraitEnvironment, TraitRef, Ty, TyDefId, ValueTyDefId,
 };
 use hir_expand::name::Name;
 
@@ -47,15 +47,15 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
         &self,
         def: DefWithBodyId,
         subst: Substitution,
-        env: Arc<crate::TraitEnvironment>,
+        env: Arc<TraitEnvironment>,
     ) -> Result<Arc<MirBody>, MirLowerError>;
 
     #[salsa::invoke(crate::mir::monomorphized_mir_body_for_closure_query)]
     fn monomorphized_mir_body_for_closure(
         &self,
         def: ClosureId,
         subst: Substitution,
-        env: Arc<crate::TraitEnvironment>,
+        env: Arc<TraitEnvironment>,
     ) -> Result<Arc<MirBody>, MirLowerError>;
 
     #[salsa::invoke(crate::mir::borrowck_query)]
@@ -81,7 +81,7 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
         &self,
         def: GeneralConstId,
         subst: Substitution,
-        trait_env: Option<Arc<crate::TraitEnvironment>>,
+        trait_env: Option<Arc<TraitEnvironment>>,
     ) -> Result<Const, ConstEvalError>;
 
     #[salsa::invoke(crate::consteval::const_eval_static_query)]
@@ -104,24 +104,20 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
         &self,
         def: AdtId,
         subst: Substitution,
-        env: Arc<crate::TraitEnvironment>,
+        env: Arc<TraitEnvironment>,
     ) -> Result<Arc<Layout>, LayoutError>;
 
     #[salsa::invoke(crate::layout::layout_of_ty_query)]
     #[salsa::cycle(crate::layout::layout_of_ty_recover)]
-    fn layout_of_ty(
-        &self,
-        ty: Ty,
-        env: Arc<crate::TraitEnvironment>,
-    ) -> Result<Arc<Layout>, LayoutError>;
+    fn layout_of_ty(&self, ty: Ty, env: Arc<TraitEnvironment>) -> Result<Arc<Layout>, LayoutError>;
 
     #[salsa::invoke(crate::layout::target_data_layout_query)]
     fn target_data_layout(&self, krate: CrateId) -> Option<Arc<TargetDataLayout>>;
 
     #[salsa::invoke(crate::method_resolution::lookup_impl_method_query)]
     fn lookup_impl_method(
         &self,
-        env: Arc<crate::TraitEnvironment>,
+        env: Arc<TraitEnvironment>,
         func: FunctionId,
         fn_subst: Substitution,
     ) -> (FunctionId, Substitution);
@@ -149,10 +145,10 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
 
     #[salsa::invoke(crate::lower::trait_environment_for_body_query)]
     #[salsa::transparent]
-    fn trait_environment_for_body(&self, def: DefWithBodyId) -> Arc<crate::TraitEnvironment>;
+    fn trait_environment_for_body(&self, def: DefWithBodyId) -> Arc<TraitEnvironment>;
 
     #[salsa::invoke(crate::lower::trait_environment_query)]
-    fn trait_environment(&self, def: GenericDefId) -> Arc<crate::TraitEnvironment>;
+    fn trait_environment(&self, def: GenericDefId) -> Arc<TraitEnvironment>;
 
     #[salsa::invoke(crate::lower::generic_defaults_query)]
     #[salsa::cycle(crate::lower::generic_defaults_recover)]
@@ -249,7 +245,7 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
     fn normalize_projection(
         &self,
         projection: crate::ProjectionTy,
-        env: Arc<crate::TraitEnvironment>,
+        env: Arc<TraitEnvironment>,
     ) -> Ty;
 
     #[salsa::invoke(trait_solve_wait)]

crates/hir-ty/src/diagnostics.rs

@@ -11,9 +11,3 @@ pub use crate::diagnostics::{
     },
     unsafe_check::{missing_unsafe, unsafe_expressions, UnsafeExpr},
 };
-
-#[derive(Debug, PartialEq, Eq)]
-pub struct IncoherentImpl {
-    pub file_id: hir_expand::HirFileId,
-    pub impl_: syntax::AstPtr<syntax::ast::Impl>,
-}

crates/hir-ty/src/layout.rs

@@ -1,5 +1,7 @@
 //! Compute the binary representation of a type
 
+use std::fmt;
+
 use chalk_ir::{AdtId, FloatTy, IntTy, TyKind, UintTy};
 use hir_def::{
     layout::{
@@ -26,12 +28,6 @@ pub use self::{
     target::target_data_layout_query,
 };
 
-macro_rules! user_error {
-    ($it: expr) => {
-        return Err(LayoutError::UserError(format!($it).into()))
-    };
-}
-
 mod adt;
 mod target;
 
@@ -73,13 +69,38 @@ pub type Variants = hir_def::layout::Variants<RustcFieldIdx, RustcEnumVariantIdx
 
 #[derive(Debug, PartialEq, Eq, Clone)]
 pub enum LayoutError {
-    UserError(Box<str>),
-    SizeOverflow,
-    TargetLayoutNotAvailable,
-    HasPlaceholder,
+    HasErrorConst,
     HasErrorType,
+    HasPlaceholder,
+    InvalidSimdType,
     NotImplemented,
+    RecursiveTypeWithoutIndirection,
+    SizeOverflow,
+    TargetLayoutNotAvailable,
     Unknown,
+    UserReprTooSmall,
+}
+
+impl std::error::Error for LayoutError {}
+impl fmt::Display for LayoutError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            LayoutError::HasErrorConst => write!(f, "type contains an unevaluatable const"),
+            LayoutError::HasErrorType => write!(f, "type contains an error"),
+            LayoutError::HasPlaceholder => write!(f, "type contains placeholders"),
+            LayoutError::InvalidSimdType => write!(f, "invalid simd type definition"),
+            LayoutError::NotImplemented => write!(f, "not implemented"),
+            LayoutError::RecursiveTypeWithoutIndirection => {
+                write!(f, "recursive type without indirection")
+            }
+            LayoutError::SizeOverflow => write!(f, "size overflow"),
+            LayoutError::TargetLayoutNotAvailable => write!(f, "target layout not available"),
+            LayoutError::Unknown => write!(f, "unknown"),
+            LayoutError::UserReprTooSmall => {
+                write!(f, "the `#[repr]` hint is too small to hold the discriminants of the enum")
+            }
+        }
+    }
 }
 
 struct LayoutCx<'a> {
@@ -118,9 +139,7 @@ fn layout_of_simd_ty(
 
     let f0_ty = match fields.iter().next() {
         Some(it) => it.1.clone().substitute(Interner, subst),
-        None => {
-            user_error!("simd type with zero fields");
-        }
+        None => return Err(LayoutError::InvalidSimdType),
     };
 
     // The element type and number of elements of the SIMD vector
@@ -134,7 +153,7 @@ fn layout_of_simd_ty(
         // Extract the number of elements from the layout of the array field:
         let FieldsShape::Array { count, .. } = db.layout_of_ty(f0_ty.clone(), env.clone())?.fields
         else {
-            user_error!("Array with non array layout");
+            return Err(LayoutError::Unknown);
         };
 
         (e_ty.clone(), count, true)
@@ -146,7 +165,7 @@ fn layout_of_simd_ty(
     // Compute the ABI of the element type:
     let e_ly = db.layout_of_ty(e_ty, env.clone())?;
     let Abi::Scalar(e_abi) = e_ly.abi else {
-        user_error!("simd type with inner non scalar type");
+        return Err(LayoutError::Unknown);
     };
 
     // Compute the size and alignment of the vector:
@@ -259,9 +278,7 @@ pub fn layout_of_ty_query(
             cx.univariant(dl, &fields, &ReprOptions::default(), kind).ok_or(LayoutError::Unknown)?
         }
         TyKind::Array(element, count) => {
-            let count = try_const_usize(db, &count).ok_or(LayoutError::UserError(Box::from(
-                "unevaluated or mistyped const generic parameter",
-            )))? as u64;
+            let count = try_const_usize(db, &count).ok_or(LayoutError::HasErrorConst)? as u64;
             let element = db.layout_of_ty(element.clone(), trait_env.clone())?;
             let size = element.size.checked_mul(count, dl).ok_or(LayoutError::SizeOverflow)?;
 
@@ -352,7 +369,7 @@ pub fn layout_of_ty_query(
             let mut unit = layout_of_unit(&cx, dl)?;
             match unit.abi {
                 Abi::Aggregate { ref mut sized } => *sized = false,
-                _ => user_error!("bug"),
+                _ => return Err(LayoutError::Unknown),
             }
             unit
         }
@@ -418,7 +435,7 @@ pub fn layout_of_ty_recover(
     _: &Ty,
     _: &Arc<TraitEnvironment>,
 ) -> Result<Arc<Layout>, LayoutError> {
-    user_error!("infinite sized recursive type");
+    Err(LayoutError::RecursiveTypeWithoutIndirection)
 }
 
 fn layout_of_unit(cx: &LayoutCx<'_>, dl: &TargetDataLayout) -> Result<Layout, LayoutError> {

crates/hir-ty/src/layout/adt.rs

@@ -145,7 +145,7 @@ pub fn layout_of_adt_recover(
     _: &Substitution,
     _: &Arc<TraitEnvironment>,
 ) -> Result<Arc<Layout>, LayoutError> {
-    user_error!("infinite sized recursive type");
+    Err(LayoutError::RecursiveTypeWithoutIndirection)
 }
 
 /// Finds the appropriate Integer type and signedness for the given
@@ -169,11 +169,7 @@ fn repr_discr(
         let discr = Integer::from_attr(dl, ity);
         let fit = if ity.is_signed() { signed_fit } else { unsigned_fit };
         if discr < fit {
-            return Err(LayoutError::UserError(
-                "Integer::repr_discr: `#[repr]` hint too small for \
-                      discriminant range of enum "
-                    .into(),
-            ));
+            return Err(LayoutError::UserReprTooSmall);
         }
         return Ok((discr, ity.is_signed()));
     }

crates/hir-ty/src/layout/tests.rs

@@ -210,16 +210,13 @@ fn recursive() {
         struct BoxLike<T: ?Sized>(*mut T);
         struct Goal(BoxLike<Goal>);
     }
-    check_fail(
-        r#"struct Goal(Goal);"#,
-        LayoutError::UserError("infinite sized recursive type".into()),
-    );
+    check_fail(r#"struct Goal(Goal);"#, LayoutError::RecursiveTypeWithoutIndirection);
     check_fail(
         r#"
         struct Foo<T>(Foo<T>);
         struct Goal(Foo<i32>);
         "#,
-        LayoutError::UserError("infinite sized recursive type".into()),
+        LayoutError::RecursiveTypeWithoutIndirection,
     );
 }
 

crates/hir-ty/src/lib.rs

@@ -80,6 +80,7 @@ pub use mapping::{
     lt_from_placeholder_idx, to_assoc_type_id, to_chalk_trait_id, to_foreign_def_id,
     to_placeholder_idx,
 };
+pub use method_resolution::check_orphan_rules;
 pub use traits::TraitEnvironment;
 pub use utils::{all_super_traits, is_fn_unsafe_to_call};