Auto merge of #143328 - oli-obk:ty-decl-wf-check, r=<try>

bors · bors · commit 51abd0965b9c · 2025-07-02T16:53:18.000Z
Avoid loading HIR for check_well_formed on type declarations

r? `@compiler-errors`

the last commit is quite hacky. I could add a `ty_span` query to work together with `def_span` and `def_ident_span`, which would nicely solve all those cases, but potentially add lots of new dep graph edges
diff --git a/compiler/rustc_errors/src/diagnostic.rs b/compiler/rustc_errors/src/diagnostic.rs
@@ -1264,6 +1264,14 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         self
     } }
 
+    with_fn! { with_replace_span,
+    /// Replace all occurrences of the first span with the second one
+    #[rustc_lint_diagnostics]
+    pub fn replace_span(&mut self, before: Span, after: Span) -> &mut Self {
+        self.span.replace(before, after);
+        self
+    } }
+
     #[rustc_lint_diagnostics]
     pub fn is_lint(&mut self, name: String, has_future_breakage: bool) -> &mut Self {
         self.is_lint = Some(IsLint { name, has_future_breakage });
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -37,8 +37,8 @@ use {rustc_attr_data_structures as attrs, rustc_hir as hir};
 use super::compare_impl_item::check_type_bounds;
 use super::*;
 use crate::check::wfcheck::{
-    check_associated_item, check_trait_item, check_variances_for_type_defn, check_where_clauses,
-    enter_wf_checking_ctxt,
+    check_associated_item, check_trait_item, check_type_defn, check_variances_for_type_defn,
+    check_where_clauses, enter_wf_checking_ctxt,
 };
 
 fn add_abi_diag_help<T: EmissionGuarantee>(abi: ExternAbi, diag: &mut Diag<'_, T>) {
@@ -89,7 +89,7 @@ pub fn check_custom_abi(tcx: TyCtxt<'_>, def_id: LocalDefId, fn_sig: FnSig<'_>,
     }
 }
 
-fn check_struct(tcx: TyCtxt<'_>, def_id: LocalDefId) {
+fn check_struct(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(), ErrorGuaranteed> {
     let def = tcx.adt_def(def_id);
     let span = tcx.def_span(def_id);
     def.destructor(tcx); // force the destructor to be evaluated
@@ -100,15 +100,17 @@ fn check_struct(tcx: TyCtxt<'_>, def_id: LocalDefId) {
 
     check_transparent(tcx, def);
     check_packed(tcx, span, def);
+    check_type_defn(tcx, def_id, false)
 }
 
-fn check_union(tcx: TyCtxt<'_>, def_id: LocalDefId) {
+fn check_union(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(), ErrorGuaranteed> {
     let def = tcx.adt_def(def_id);
     let span = tcx.def_span(def_id);
     def.destructor(tcx); // force the destructor to be evaluated
     check_transparent(tcx, def);
     check_union_fields(tcx, span, def_id);
     check_packed(tcx, span, def);
+    check_type_defn(tcx, def_id, true)
 }
 
 fn allowed_union_or_unsafe_field<'tcx>(
@@ -782,9 +784,12 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(),
             tcx.ensure_ok().generics_of(def_id);
             tcx.ensure_ok().type_of(def_id);
             tcx.ensure_ok().predicates_of(def_id);
-            crate::collect::lower_enum_variant_types(tcx, def_id.to_def_id());
+            crate::collect::check_enum_variant_types(tcx, def_id.to_def_id());
             check_enum(tcx, def_id);
             check_variances_for_type_defn(tcx, def_id);
+            res = res.and(check_type_defn(tcx, def_id, true));
+            // enums are fully handled by the type based check and have no hir wfcheck logic
+            return res;
         }
         DefKind::Fn => {
             tcx.ensure_ok().generics_of(def_id);
@@ -844,12 +849,19 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(),
                     _ => {}
                 }
             }
+            res = res.and(wfcheck::check_trait(tcx, def_id));
+            wfcheck::check_gat_where_clauses(tcx, def_id);
+            // Trait aliases do not have hir checks anymore
+            return res;
         }
         DefKind::TraitAlias => {
             tcx.ensure_ok().generics_of(def_id);
             tcx.ensure_ok().explicit_implied_predicates_of(def_id);
             tcx.ensure_ok().explicit_super_predicates_of(def_id);
             tcx.ensure_ok().predicates_of(def_id);
+            res = res.and(wfcheck::check_trait(tcx, def_id));
+            // Trait aliases do not have hir checks anymore
+            return res;
         }
         def_kind @ (DefKind::Struct | DefKind::Union) => {
             tcx.ensure_ok().generics_of(def_id);
@@ -864,14 +876,16 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(),
             }
 
             if let Some((_, ctor_def_id)) = adt.ctor {
-                crate::collect::lower_variant_ctor(tcx, ctor_def_id.expect_local());
+                crate::collect::check_ctor(tcx, ctor_def_id.expect_local());
             }
-            match def_kind {
+            res = res.and(match def_kind {
                 DefKind::Struct => check_struct(tcx, def_id),
                 DefKind::Union => check_union(tcx, def_id),
                 _ => unreachable!(),
-            }
+            });
             check_variances_for_type_defn(tcx, def_id);
+            // structs and enums are fully handled by the type based check and have no hir wfcheck logic
+            return res;
         }
         DefKind::OpaqueTy => {
             check_opaque_precise_captures(tcx, def_id);
@@ -922,6 +936,8 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(),
                 }));
                 check_variances_for_type_defn(tcx, def_id);
             }
+            // Doesn't have any hir based checks
+            return res;
         }
         DefKind::ForeignMod => {
             let it = tcx.hir_expect_item(def_id);
@@ -984,6 +1000,8 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(),
                     _ => (),
                 }
             }
+            // Doesn't have any hir based checks
+            return res;
         }
         DefKind::Closure => {
             // This is guaranteed to be called by metadata encoding,
@@ -1059,10 +1077,14 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(),
             return res;
         }
 
-        // Only `Node::Item` and `Node::ForeignItem` still have HIR based
-        // checks. Returning early here does not miss any checks and
-        // avoids this query from having a direct dependency edge on the HIR
-        DefKind::AnonConst | DefKind::InlineConst => return res,
+        // These have no wf checks
+        DefKind::AnonConst
+        | DefKind::InlineConst
+        | DefKind::ExternCrate
+        | DefKind::Macro(..)
+        | DefKind::Use
+        | DefKind::GlobalAsm
+        | DefKind::Mod => return res,
         _ => {}
     }
     let node = tcx.hir_node_by_def_id(def_id);
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -19,9 +19,8 @@ use rustc_middle::query::Providers;
 use rustc_middle::traits::solve::NoSolution;
 use rustc_middle::ty::trait_def::TraitSpecializationKind;
 use rustc_middle::ty::{
-    self, AdtKind, GenericArgKind, GenericArgs, GenericParamDefKind, Ty, TyCtxt, TypeFlags,
-    TypeFoldable, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor, TypingMode,
-    Upcast,
+    self, GenericArgKind, GenericArgs, GenericParamDefKind, Ty, TyCtxt, TypeFlags, TypeFoldable,
+    TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor, TypingMode, Upcast,
 };
 use rustc_middle::{bug, span_bug};
 use rustc_session::parse::feature_err;
@@ -289,12 +288,8 @@ pub(super) fn check_item<'tcx>(
         }
         hir::ItemKind::Fn { sig, .. } => check_item_fn(tcx, def_id, sig.decl),
         hir::ItemKind::Const(_, _, ty, _) => check_const_item(tcx, def_id, ty.span),
-        hir::ItemKind::Struct(..) => check_type_defn(tcx, item, false),
-        hir::ItemKind::Union(..) => check_type_defn(tcx, item, true),
-        hir::ItemKind::Enum(..) => check_type_defn(tcx, item, true),
-        hir::ItemKind::Trait(..) => check_trait(tcx, item),
-        hir::ItemKind::TraitAlias(..) => check_trait(tcx, item),
-        _ => Ok(()),
+        // Note: do not add new entries to this match. Instead add all new logic in `check_item_type`
+        _ => span_bug!(item.span, "should have been handled by the type based wf check: {item:?}"),
     }
 }
 
@@ -344,7 +339,7 @@ pub(crate) fn check_trait_item<'tcx>(
 ///     fn into_iter<'a>(&'a self) -> Self::Iter<'a>;
 /// }
 /// ```
-fn check_gat_where_clauses(tcx: TyCtxt<'_>, trait_def_id: LocalDefId) {
+pub(crate) fn check_gat_where_clauses(tcx: TyCtxt<'_>, trait_def_id: LocalDefId) {
     // Associates every GAT's def_id to a list of possibly missing bounds detected by this lint.
     let mut required_bounds_by_item = FxIndexMap::default();
     let associated_items = tcx.associated_items(trait_def_id);
@@ -990,15 +985,15 @@ pub(crate) fn check_associated_item(
 }
 
 /// In a type definition, we check that to ensure that the types of the fields are well-formed.
-fn check_type_defn<'tcx>(
+pub(crate) fn check_type_defn<'tcx>(
     tcx: TyCtxt<'tcx>,
-    item: &hir::Item<'tcx>,
+    item: LocalDefId,
     all_sized: bool,
 ) -> Result<(), ErrorGuaranteed> {
-    let _ = tcx.representability(item.owner_id.def_id);
-    let adt_def = tcx.adt_def(item.owner_id);
+    let _ = tcx.representability(item);
+    let adt_def = tcx.adt_def(item);
 
-    enter_wf_checking_ctxt(tcx, item.owner_id.def_id, |wfcx| {
+    enter_wf_checking_ctxt(tcx, item, |wfcx| {
         let variants = adt_def.variants();
         let packed = adt_def.repr().packed();
 
@@ -1056,35 +1051,21 @@ fn check_type_defn<'tcx>(
                 variant.fields.raw[..variant.fields.len() - unsized_len].iter().enumerate()
             {
                 let last = idx == variant.fields.len() - 1;
-                let field_id = field.did.expect_local();
-                let hir::FieldDef { ty: hir_ty, .. } =
-                    tcx.hir_node_by_def_id(field_id).expect_field();
-                let ty = wfcx.normalize(
-                    hir_ty.span,
-                    None,
-                    tcx.type_of(field.did).instantiate_identity(),
-                );
+                let span = tcx.def_span(field.did);
+                let ty = wfcx.normalize(span, None, tcx.type_of(field.did).instantiate_identity());
                 wfcx.register_bound(
                     traits::ObligationCause::new(
-                        hir_ty.span,
+                        span,
                         wfcx.body_def_id,
                         ObligationCauseCode::FieldSized {
-                            adt_kind: match &item.kind {
-                                ItemKind::Struct(..) => AdtKind::Struct,
-                                ItemKind::Union(..) => AdtKind::Union,
-                                ItemKind::Enum(..) => AdtKind::Enum,
-                                kind => span_bug!(
-                                    item.span,
-                                    "should be wfchecking an ADT, got {kind:?}"
-                                ),
-                            },
-                            span: hir_ty.span,
+                            adt_kind: adt_def.adt_kind(),
+                            field: field.did,
                             last,
                         },
                     ),
                     wfcx.param_env,
                     ty,
-                    tcx.require_lang_item(LangItem::Sized, hir_ty.span),
+                    tcx.require_lang_item(LangItem::Sized, span),
                 );
             }
 
@@ -1100,16 +1081,13 @@ fn check_type_defn<'tcx>(
             }
         }
 
-        check_where_clauses(wfcx, item.owner_id.def_id);
+        check_where_clauses(wfcx, item);
         Ok(())
     })
 }
 
-#[instrument(skip(tcx, item))]
-fn check_trait(tcx: TyCtxt<'_>, item: &hir::Item<'_>) -> Result<(), ErrorGuaranteed> {
-    debug!(?item.owner_id);
-
-    let def_id = item.owner_id.def_id;
+#[instrument(skip(tcx))]
+pub(crate) fn check_trait(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(), ErrorGuaranteed> {
     if tcx.is_lang_item(def_id.into(), LangItem::PointeeSized) {
         // `PointeeSized` is removed during lowering.
         return Ok(());
@@ -1135,10 +1113,6 @@ fn check_trait(tcx: TyCtxt<'_>, item: &hir::Item<'_>) -> Result<(), ErrorGuarant
         Ok(())
     });
 
-    // Only check traits, don't check trait aliases
-    if let hir::ItemKind::Trait(..) = item.kind {
-        check_gat_where_clauses(tcx, item.owner_id.def_id);
-    }
     res
 }
 
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
@@ -605,13 +605,13 @@ fn get_new_lifetime_name<'tcx>(
     (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
 }
 
-pub(super) fn lower_variant_ctor(tcx: TyCtxt<'_>, def_id: LocalDefId) {
+pub(super) fn check_ctor(tcx: TyCtxt<'_>, def_id: LocalDefId) {
     tcx.ensure_ok().generics_of(def_id);
     tcx.ensure_ok().type_of(def_id);
     tcx.ensure_ok().predicates_of(def_id);
 }
 
-pub(super) fn lower_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId) {
+pub(super) fn check_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId) {
     let def = tcx.adt_def(def_id);
     let repr_type = def.repr().discr_type();
     let initial = repr_type.initial_discriminant(tcx);
@@ -646,7 +646,7 @@ pub(super) fn lower_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId) {
 
         // Lower the ctor, if any. This also registers the variant as an item.
         if let Some(ctor_def_id) = variant.ctor_def_id() {
-            lower_variant_ctor(tcx, ctor_def_id.expect_local());
+            check_ctor(tcx, ctor_def_id.expect_local());
         }
     }
 }
diff --git a/compiler/rustc_hir_typeck/src/expr.rs b/compiler/rustc_hir_typeck/src/expr.rs
@@ -3910,7 +3910,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         expr.span,
                         ObligationCauseCode::FieldSized {
                             adt_kind: AdtKind::Enum,
-                            span: self.tcx.def_span(field.did),
+                            field: field.did,
                             last: false,
                         },
                     );
diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
@@ -261,7 +261,7 @@ pub enum ObligationCauseCode<'tcx> {
     /// Types of fields (other than the last, except for packed structs) in a struct must be sized.
     FieldSized {
         adt_kind: AdtKind,
-        span: Span,
+        field: DefId,
         last: bool,
     },
 
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
@@ -3121,7 +3121,13 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             ObligationCauseCode::StructInitializerSized => {
                 err.note("structs must have a statically known size to be initialized");
             }
-            ObligationCauseCode::FieldSized { adt_kind: ref item, last, span } => {
+            ObligationCauseCode::FieldSized { adt_kind: ref item, last, field } => {
+                let def_span = tcx.def_span(field);
+                let span = field
+                    .as_local()
+                    .map(|field| tcx.hir_node_by_def_id(field).expect_field().ty.span)
+                    .unwrap_or(def_span);
+                err.replace_span(def_span, span);
                 match *item {
                     AdtKind::Struct => {
                         if last {
diff --git a/tests/ui/generic-associated-types/static-lifetime-tip-with-default-type.stderr b/tests/ui/generic-associated-types/static-lifetime-tip-with-default-type.stderr
@@ -82,14 +82,6 @@ help: consider adding an explicit lifetime bound
 LL | struct Far<T: 'static
    |             +++++++++
 
-error[E0392]: lifetime parameter `'a` is never used
-  --> $DIR/static-lifetime-tip-with-default-type.rs:22:10
-   |
-LL | struct S<'a, K: 'a = i32>(&'static K);
-   |          ^^ unused lifetime parameter
-   |
-   = help: consider removing `'a`, referring to it in a field, or using a marker such as `PhantomData`
-
 error[E0310]: the parameter type `K` may not live long enough
   --> $DIR/static-lifetime-tip-with-default-type.rs:22:27
    |
@@ -104,6 +96,14 @@ help: consider adding an explicit lifetime bound
 LL | struct S<'a, K: 'a + 'static = i32>(&'static K);
    |                    +++++++++
 
+error[E0392]: lifetime parameter `'a` is never used
+  --> $DIR/static-lifetime-tip-with-default-type.rs:22:10
+   |
+LL | struct S<'a, K: 'a = i32>(&'static K);
+   |          ^^ unused lifetime parameter
+   |
+   = help: consider removing `'a`, referring to it in a field, or using a marker such as `PhantomData`
+
 error: aborting due to 8 previous errors
 
 Some errors have detailed explanations: E0310, E0392.
diff --git a/tests/ui/lifetimes/issue-64173-unused-lifetimes.stderr b/tests/ui/lifetimes/issue-64173-unused-lifetimes.stderr
@@ -7,6 +7,12 @@ LL |     beta: [(); foo::<&'a ()>()],
    = note: lifetime parameters may not be used in const expressions
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
+error: generic `Self` types are currently not permitted in anonymous constants
+  --> $DIR/issue-64173-unused-lifetimes.rs:4:28
+   |
+LL |     array: [(); size_of::<&Self>()],
+   |                            ^^^^
+
 error[E0392]: lifetime parameter `'s` is never used
   --> $DIR/issue-64173-unused-lifetimes.rs:3:12
    |
@@ -15,12 +21,6 @@ LL | struct Foo<'s> {
    |
    = help: consider removing `'s`, referring to it in a field, or using a marker such as `PhantomData`
 
-error: generic `Self` types are currently not permitted in anonymous constants
-  --> $DIR/issue-64173-unused-lifetimes.rs:4:28
-   |
-LL |     array: [(); size_of::<&Self>()],
-   |                            ^^^^
-
 error[E0392]: lifetime parameter `'a` is never used
   --> $DIR/issue-64173-unused-lifetimes.rs:15:12
    |
diff --git a/tests/ui/regions/region-bounds-on-objects-and-type-parameters.stderr b/tests/ui/regions/region-bounds-on-objects-and-type-parameters.stderr
diff --git a/tests/ui/traits/issue-105231.stderr b/tests/ui/traits/issue-105231.stderr

Original file line number	Diff line number	Diff line change
`@@ -605,13 +605,13 @@ fn get_new_lifetime_name<'tcx>(`
`605`	`605`	`(1..).flat_map(a_to_z_repeat_n).find(\|lt\| !existing_lifetimes.contains(lt.as_str())).unwrap()`
`606`	`606`	`}`
`607`	`607`
`608`		`-pub(super) fn lower_variant_ctor(tcx: TyCtxt<'_>, def_id: LocalDefId) {`
	`608`	`+pub(super) fn check_ctor(tcx: TyCtxt<'_>, def_id: LocalDefId) {`
`609`	`609`	`tcx.ensure_ok().generics_of(def_id);`
`610`	`610`	`tcx.ensure_ok().type_of(def_id);`
`611`	`611`	`tcx.ensure_ok().predicates_of(def_id);`
`612`	`612`	`}`
`613`	`613`
`614`		`-pub(super) fn lower_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId) {`
	`614`	`+pub(super) fn check_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId) {`
`615`	`615`	`let def = tcx.adt_def(def_id);`
`616`	`616`	`let repr_type = def.repr().discr_type();`
`617`	`617`	`let initial = repr_type.initial_discriminant(tcx);`
`@@ -646,7 +646,7 @@ pub(super) fn lower_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId) {`
`646`	`646`
`647`	`647`	`// Lower the ctor, if any. This also registers the variant as an item.`
`648`	`648`	`if let Some(ctor_def_id) = variant.ctor_def_id() {`
`649`		`- lower_variant_ctor(tcx, ctor_def_id.expect_local());`
	`649`	`+ check_ctor(tcx, ctor_def_id.expect_local());`
`650`	`650`	`}`
`651`	`651`	`}`
`652`	`652`	`}`