Add span for struct tail recursion limit error

modhanami · modhanami · commit 6912631d3ead · 2025-09-16T23:04:59.000+07:00
diff --git a/compiler/rustc_borrowck/src/type_check/canonical.rs b/compiler/rustc_borrowck/src/type_check/canonical.rs
@@ -230,8 +230,14 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         location: impl NormalizeLocation,
     ) -> Ty<'tcx> {
         let tcx = self.tcx();
+        let body = self.body;
+
+        let cause = ObligationCause::misc(
+            location.to_locations().span(body),
+            body.source.def_id().expect_local(),
+        );
+
         if self.infcx.next_trait_solver() {
-            let body = self.body;
             let param_env = self.infcx.param_env;
             // FIXME: Make this into a real type op?
             self.fully_perform_op(
@@ -241,10 +247,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     |ocx| {
                         let structurally_normalize = |ty| {
                             ocx.structurally_normalize_ty(
-                                &ObligationCause::misc(
-                                    location.to_locations().span(body),
-                                    body.source.def_id().expect_local(),
-                                ),
+                                &cause,
                                 param_env,
                                 ty,
                             )
@@ -253,6 +256,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
 
                         let tail = tcx.struct_tail_raw(
                             ty,
+                            &cause,
                             structurally_normalize,
                             || {},
                         );
@@ -265,7 +269,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             .unwrap_or_else(|guar| Ty::new_error(tcx, guar))
         } else {
             let mut normalize = |ty| self.normalize(ty, location);
-            let tail = tcx.struct_tail_raw(ty, &mut normalize, || {});
+            let tail = tcx.struct_tail_raw(ty, &cause, &mut normalize, || {});
             normalize(tail)
         }
     }
diff --git a/compiler/rustc_const_eval/src/const_eval/valtrees.rs b/compiler/rustc_const_eval/src/const_eval/valtrees.rs
@@ -1,6 +1,7 @@
 use rustc_abi::{BackendRepr, FieldIdx, VariantIdx};
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_middle::mir::interpret::{EvalToValTreeResult, GlobalId, ValTreeCreationError};
+use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::layout::{LayoutCx, TyAndLayout};
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::{bug, mir};
@@ -196,6 +197,7 @@ fn reconstruct_place_meta<'tcx>(
     // Traverse the type, and update `last_valtree` as we go.
     let tail = tcx.struct_tail_raw(
         layout.ty,
+        &ObligationCause::dummy(),
         |ty| ty,
         || {
             let branches = last_valtree.unwrap_branch();
diff --git a/compiler/rustc_hir_typeck/src/expectation.rs b/compiler/rustc_hir_typeck/src/expectation.rs
@@ -1,3 +1,4 @@
+use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::{self, Ty};
 use rustc_span::Span;
 
@@ -74,8 +75,14 @@ impl<'a, 'tcx> Expectation<'tcx> {
     /// See the test case `test/ui/coerce-expect-unsized.rs` and #20169
     /// for examples of where this comes up,.
     pub(super) fn rvalue_hint(fcx: &FnCtxt<'a, 'tcx>, ty: Ty<'tcx>) -> Expectation<'tcx> {
+        let span = match ty.kind() {
+            ty::Adt(adt_def, _) => fcx.tcx.def_span(adt_def.did()),
+            _ => fcx.tcx.def_span(fcx.body_id),
+        };
+        let cause = ObligationCause::misc(span, fcx.body_id);
+
         // FIXME: This is not right, even in the old solver...
-        match fcx.tcx.struct_tail_raw(ty, |ty| ty, || {}).kind() {
+        match fcx.tcx.struct_tail_raw(ty, &cause, |ty| ty, || {}).kind() {
             ty::Slice(_) | ty::Str | ty::Dynamic(..) => ExpectRvalueLikeUnsized(ty),
             _ => ExpectHasType(ty),
         }
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
@@ -424,6 +424,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         if !ty.references_error() {
             let tail = self.tcx.struct_tail_raw(
                 ty,
+                &self.misc(span),
                 |ty| {
                     if self.next_trait_solver() {
                         self.try_structurally_resolve_type(span, ty)
diff --git a/compiler/rustc_middle/src/error.rs b/compiler/rustc_middle/src/error.rs
@@ -71,6 +71,8 @@ pub enum TypeMismatchReason {
 #[diag(middle_recursion_limit_reached)]
 #[help]
 pub(crate) struct RecursionLimitReached<'tcx> {
+    #[primary_span]
+    pub span: Span,
     pub ty: Ty<'tcx>,
     pub suggested_limit: rustc_hir::limit::Limit,
 }
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
@@ -22,6 +22,7 @@ use {rustc_abi as abi, rustc_hir as hir};
 
 use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use crate::query::TyCtxtAt;
+use crate::traits::ObligationCause;
 use crate::ty::normalize_erasing_regions::NormalizationError;
 use crate::ty::{self, CoroutineArgsExt, Ty, TyCtxt, TypeVisitableExt};
 
@@ -384,6 +385,7 @@ impl<'tcx> SizeSkeleton<'tcx> {
 
                 let tail = tcx.struct_tail_raw(
                     pointee,
+                    &ObligationCause::dummy(),
                     |ty| match tcx.try_normalize_erasing_regions(typing_env, ty) {
                         Ok(ty) => ty,
                         Err(e) => Ty::new_error_with_message(
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
@@ -23,6 +23,7 @@ use ty::util::IntTypeExt;
 
 use super::GenericParamDefKind;
 use crate::infer::canonical::Canonical;
+use crate::traits::ObligationCause;
 use crate::ty::InferTy::*;
 use crate::ty::{
     self, AdtDef, BoundRegionKind, Discr, GenericArg, GenericArgs, GenericArgsRef, List, ParamEnv,
@@ -1640,7 +1641,7 @@ impl<'tcx> Ty<'tcx> {
         tcx: TyCtxt<'tcx>,
         normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>,
     ) -> Result<Ty<'tcx>, Ty<'tcx>> {
-        let tail = tcx.struct_tail_raw(self, normalize, || {});
+        let tail = tcx.struct_tail_raw(self, &ObligationCause::dummy(), normalize, || {});
         match tail.kind() {
             // Sized types
             ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
@@ -24,6 +24,7 @@ use super::TypingEnv;
 use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use crate::mir;
 use crate::query::Providers;
+use crate::traits::ObligationCause;
 use crate::ty::layout::{FloatExt, IntegerExt};
 use crate::ty::{
     self, Asyncness, FallibleTypeFolder, GenericArgKind, GenericArgsRef, Ty, TyCtxt, TypeFoldable,
@@ -216,7 +217,12 @@ impl<'tcx> TyCtxt<'tcx> {
         typing_env: ty::TypingEnv<'tcx>,
     ) -> Ty<'tcx> {
         let tcx = self;
-        tcx.struct_tail_raw(ty, |ty| tcx.normalize_erasing_regions(typing_env, ty), || {})
+        tcx.struct_tail_raw(
+            ty,
+            &ObligationCause::dummy(),
+            |ty| tcx.normalize_erasing_regions(typing_env, ty),
+            || {},
+        )
     }
 
     /// Returns true if a type has metadata.
@@ -248,6 +254,7 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn struct_tail_raw(
         self,
         mut ty: Ty<'tcx>,
+        cause: &ObligationCause<'tcx>,
         mut normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>,
         // This is currently used to allow us to walk a ValTree
         // in lockstep with the type in order to get the ValTree branch that
@@ -261,9 +268,11 @@ impl<'tcx> TyCtxt<'tcx> {
                     Limit(0) => Limit(2),
                     limit => limit * 2,
                 };
-                let reported = self
-                    .dcx()
-                    .emit_err(crate::error::RecursionLimitReached { ty, suggested_limit });
+                let reported = self.dcx().emit_err(crate::error::RecursionLimitReached {
+                    span: cause.span,
+                    ty,
+                    suggested_limit,
+                });
                 return Ty::new_error(self, reported);
             }
             match *ty.kind() {
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -1057,6 +1057,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
                     Some(LangItem::PointeeTrait) => {
                         let tail = selcx.tcx().struct_tail_raw(
                             self_ty,
+                            &obligation.cause,
                             |ty| {
                                 // We throw away any obligations we get from this, since we normalize
                                 // and confirm these obligations once again during confirmation
diff --git a/compiler/rustc_ty_utils/src/layout.rs b/compiler/rustc_ty_utils/src/layout.rs
@@ -10,6 +10,7 @@ use rustc_hashes::Hash64;
 use rustc_index::IndexVec;
 use rustc_middle::bug;
 use rustc_middle::query::Providers;
+use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::layout::{
     FloatExt, HasTyCtxt, IntegerExt, LayoutCx, LayoutError, LayoutOf, TyAndLayout,
 };
@@ -390,30 +391,31 @@ fn layout_of_uncached<'tcx>(
 
             let metadata = if let Some(metadata_def_id) = tcx.lang_items().metadata_type() {
                 let pointee_metadata = Ty::new_projection(tcx, metadata_def_id, [pointee]);
-                let metadata_ty =
-                    match tcx.try_normalize_erasing_regions(cx.typing_env, pointee_metadata) {
-                        Ok(metadata_ty) => metadata_ty,
-                        Err(mut err) => {
-                            // Usually `<Ty as Pointee>::Metadata` can't be normalized because
-                            // its struct tail cannot be normalized either, so try to get a
-                            // more descriptive layout error here, which will lead to less confusing
-                            // diagnostics.
-                            //
-                            // We use the raw struct tail function here to get the first tail
-                            // that is an alias, which is likely the cause of the normalization
-                            // error.
-                            match tcx.try_normalize_erasing_regions(
-                                cx.typing_env,
-                                tcx.struct_tail_raw(pointee, |ty| ty, || {}),
-                            ) {
-                                Ok(_) => {}
-                                Err(better_err) => {
-                                    err = better_err;
-                                }
+                let metadata_ty = match tcx
+                    .try_normalize_erasing_regions(cx.typing_env, pointee_metadata)
+                {
+                    Ok(metadata_ty) => metadata_ty,
+                    Err(mut err) => {
+                        // Usually `<Ty as Pointee>::Metadata` can't be normalized because
+                        // its struct tail cannot be normalized either, so try to get a
+                        // more descriptive layout error here, which will lead to less confusing
+                        // diagnostics.
+                        //
+                        // We use the raw struct tail function here to get the first tail
+                        // that is an alias, which is likely the cause of the normalization
+                        // error.
+                        match tcx.try_normalize_erasing_regions(
+                            cx.typing_env,
+                            tcx.struct_tail_raw(pointee, &ObligationCause::dummy(), |ty| ty, || {}),
+                        ) {
+                            Ok(_) => {}
+                            Err(better_err) => {
+                                err = better_err;
                             }
-                            return Err(error(cx, LayoutError::NormalizationFailure(pointee, err)));
                         }
-                    };
+                        return Err(error(cx, LayoutError::NormalizationFailure(pointee, err)));
+                    }
+                };
 
                 let metadata_layout = cx.layout_of(metadata_ty)?;
                 // If the metadata is a 1-zst, then the pointer is thin.
diff --git a/compiler/rustc_ty_utils/src/ty.rs b/compiler/rustc_ty_utils/src/ty.rs
@@ -353,6 +353,7 @@ fn impl_self_is_guaranteed_unsized<'tcx>(tcx: TyCtxt<'tcx>, impl_def_id: DefId)
 
     let tail = tcx.struct_tail_raw(
         tcx.type_of(impl_def_id).instantiate_identity(),
+        &cause,
         |ty| {
             ocx.structurally_normalize_ty(&cause, param_env, ty).unwrap_or_else(|_| {
                 Ty::new_error_with_message(
diff --git a/tests/ui/did_you_mean/recursion_limit_deref.rs b/tests/ui/did_you_mean/recursion_limit_deref.rs
@@ -1,3 +1,6 @@
+//~ ERROR reached the recursion limit finding the struct tail for `K`
+//~| ERROR reached the recursion limit finding the struct tail for `Bottom`
+
 // Test that the recursion limit can be changed and that the compiler
 // suggests a fix. In this case, we have a long chain of Deref impls
 // which will cause an overflow during the autoderef loop.
@@ -9,6 +12,7 @@
 macro_rules! link {
     ($outer:ident, $inner:ident) => {
         struct $outer($inner);
+        //~^ ERROR reached the recursion limit finding the struct tail for `Bottom`
 
         impl $outer {
             fn new() -> $outer {
@@ -51,6 +55,3 @@ fn main() {
     let x: &Bottom = &t; //~ ERROR mismatched types
     //~^ error recursion limit
 }
-
-//~? ERROR reached the recursion limit finding the struct tail for `K`
-//~? ERROR reached the recursion limit finding the struct tail for `Bottom`
diff --git a/tests/ui/did_you_mean/recursion_limit_deref.stderr b/tests/ui/did_you_mean/recursion_limit_deref.stderr
@@ -6,16 +6,28 @@ error: reached the recursion limit finding the struct tail for `Bottom`
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "20"]`
 
+error: reached the recursion limit finding the struct tail for `Bottom`
+  --> $DIR/recursion_limit_deref.rs:14:9
+   |
+LL |         struct $outer($inner);
+   |         ^^^^^^^^^^^^^^^^^^^^^^
+...
+LL | link!(A, B);
+   | ----------- in this macro invocation
+   |
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "20"]`
+   = note: this error originates in the macro `link` (in Nightly builds, run with -Z macro-backtrace for more info)
+
 error[E0055]: reached the recursion limit while auto-dereferencing `J`
-  --> $DIR/recursion_limit_deref.rs:51:22
+  --> $DIR/recursion_limit_deref.rs:55:22
    |
 LL |     let x: &Bottom = &t;
    |                      ^^ deref recursion limit reached
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "20"]` attribute to your crate (`recursion_limit_deref`)
 
 error[E0308]: mismatched types
-  --> $DIR/recursion_limit_deref.rs:51:22
+  --> $DIR/recursion_limit_deref.rs:55:22
    |
 LL |     let x: &Bottom = &t;
    |            -------   ^^ expected `&Bottom`, found `&Top`
@@ -25,7 +37,7 @@ LL |     let x: &Bottom = &t;
    = note: expected reference `&Bottom`
               found reference `&Top`
 
-error: aborting due to 4 previous errors
+error: aborting due to 5 previous errors
 
 Some errors have detailed explanations: E0055, E0308.
 For more information about an error, try `rustc --explain E0055`.
diff --git a/tests/ui/infinite/infinite-instantiation-struct-tail-ice-114484.rs b/tests/ui/infinite/infinite-instantiation-struct-tail-ice-114484.rs
@@ -1,4 +1,17 @@
-//~ ERROR reached the recursion limit while instantiating `<VirtualWrapper<
+//~ ERROR reached the recursion limit finding the struct tail for `[u8; 256]`
+//~| ERROR reached the recursion limit finding the struct tail for `[u8; 256]`
+//~| ERROR reached the recursion limit finding the struct tail for `[u8; 256]`
+//~| ERROR reached the recursion limit finding the struct tail for `[u8; 256]`
+//~| ERROR reached the recursion limit finding the struct tail for `SomeData<256>`
+//~| ERROR reached the recursion limit finding the struct tail for `SomeData<256>`
+//~| ERROR reached the recursion limit finding the struct tail for `SomeData<256>`
+//~| ERROR reached the recursion limit finding the struct tail for `SomeData<256>`
+//~| ERROR reached the recursion limit finding the struct tail for `VirtualWrapper<SomeData<256>, 0>`
+//~| ERROR reached the recursion limit finding the struct tail for `VirtualWrapper<SomeData<256>, 0>`
+//~| ERROR reached the recursion limit finding the struct tail for `VirtualWrapper<SomeData<256>, 0>`
+//~| ERROR reached the recursion limit finding the struct tail for `VirtualWrapper<SomeData<256>, 0>`
+//~| ERROR reached the recursion limit while instantiating `<VirtualWrapper<..., 1> as MyTrait>::virtualize`
+
 //@ build-fail
 //@ compile-flags: --diagnostic-width=100 -Zwrite-long-types-to-disk=yes
 
@@ -72,16 +85,3 @@ fn main() {
     let test = SomeData([0; 256]);
     test.virtualize();
 }
-
-//~? ERROR reached the recursion limit finding the struct tail for `[u8; 256]`
-//~? ERROR reached the recursion limit finding the struct tail for `[u8; 256]`
-//~? ERROR reached the recursion limit finding the struct tail for `[u8; 256]`
-//~? ERROR reached the recursion limit finding the struct tail for `[u8; 256]`
-//~? ERROR reached the recursion limit finding the struct tail for `SomeData<256>`
-//~? ERROR reached the recursion limit finding the struct tail for `SomeData<256>`
-//~? ERROR reached the recursion limit finding the struct tail for `SomeData<256>`
-//~? ERROR reached the recursion limit finding the struct tail for `SomeData<256>`
-//~? ERROR reached the recursion limit finding the struct tail for `VirtualWrapper<SomeData<256>, 0>`
-//~? ERROR reached the recursion limit finding the struct tail for `VirtualWrapper<SomeData<256>, 0>`
-//~? ERROR reached the recursion limit finding the struct tail for `VirtualWrapper<SomeData<256>, 0>`
-//~? ERROR reached the recursion limit finding the struct tail for `VirtualWrapper<SomeData<256>, 0>`
diff --git a/tests/ui/infinite/infinite-instantiation-struct-tail-ice-114484.stderr b/tests/ui/infinite/infinite-instantiation-struct-tail-ice-114484.stderr
@@ -18,7 +18,7 @@ error: reached the recursion limit finding the struct tail for `[u8; 256]`
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 note: the above error was encountered while instantiating `fn virtualize_my_trait::<VirtualWrapper<..., 1>>`
-  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:25:18
+  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:38:18
    |
 LL |         unsafe { virtualize_my_trait(L, self) }
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -46,7 +46,7 @@ error: reached the recursion limit finding the struct tail for `SomeData<256>`
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 note: the above error was encountered while instantiating `fn virtualize_my_trait::<VirtualWrapper<..., 1>>`
-  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:25:18
+  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:38:18
    |
 LL |         unsafe { virtualize_my_trait(L, self) }
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -74,7 +74,7 @@ error: reached the recursion limit finding the struct tail for `VirtualWrapper<S
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 note: the above error was encountered while instantiating `fn virtualize_my_trait::<VirtualWrapper<..., 1>>`
-  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:25:18
+  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:38:18
    |
 LL |         unsafe { virtualize_my_trait(L, self) }
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -85,7 +85,7 @@ LL |         unsafe { virtualize_my_trait(L, self) }
 error: reached the recursion limit while instantiating `<VirtualWrapper<..., 1> as MyTrait>::virtualize`
    |
 note: `<VirtualWrapper<T, L> as MyTrait>::virtualize` defined here
-  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:24:5
+  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:37:5
    |
 LL |     fn virtualize(&self) -> &dyn MyTrait {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/infinite/infinite-struct.rs b/tests/ui/infinite/infinite-struct.rs
diff --git a/tests/ui/infinite/infinite-struct.stderr b/tests/ui/infinite/infinite-struct.stderr
diff --git a/tests/ui/invalid/issue-114435-layout-type-err.rs b/tests/ui/invalid/issue-114435-layout-type-err.rs
diff --git a/tests/ui/traits/solver-cycles/129541-recursive-struct.rs b/tests/ui/traits/solver-cycles/129541-recursive-struct.rs

Original file line number	Diff line number	Diff line change
`@@ -71,6 +71,8 @@ pub enum TypeMismatchReason {`
`71`	`71`	`#[diag(middle_recursion_limit_reached)]`
`72`	`72`	`#[help]`
`73`	`73`	`pub(crate) struct RecursionLimitReached<'tcx> {`
	`74`	`+ #[primary_span]`
	`75`	`+ pub span: Span,`
`74`	`76`	`pub ty: Ty<'tcx>,`
`75`	`77`	`pub suggested_limit: rustc_hir::limit::Limit,`
`76`	`78`	`}`