5 files changed, 25 insertions, 5 deletions
diff --git a/compiler/rustc_middle/src/error.rs b/compiler/rustc_middle/src/error.rs
index dad402ec696..e3e1393b5f9 100644
--- 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/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
index ab8a3142953..0c7bddf60d9 100644
--- a/compiler/rustc_middle/src/traits/mod.rs
+++ b/compiler/rustc_middle/src/traits/mod.rs
@@ -823,6 +823,9 @@ impl DynCompatibilityViolation {
             DynCompatibilityViolation::Method(name, MethodViolationCode::AsyncFn, _) => {
                 format!("method `{name}` is `async`").into()
             }
+            DynCompatibilityViolation::Method(name, MethodViolationCode::CVariadic, _) => {
+                format!("method `{name}` is C-variadic").into()
+            }
             DynCompatibilityViolation::Method(
                 name,
                 MethodViolationCode::WhereClauseReferencesSelf,
@@ -977,6 +980,9 @@ pub enum MethodViolationCode {
     /// e.g., `fn foo<A>()`
     Generic,
 
+    /// e.g., `fn (mut ap: ...)`
+    CVariadic,
+
     /// the method's receiver (`self` argument) can't be dispatched on
     UndispatchableReceiver(Option<Span>),
 }
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 9524057eebc..c477e65f5d6 100644
--- 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
index 2bea7977999..de35e5e847c 100644
--- 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,
@@ -1638,7 +1639,7 @@ 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
index b79b67c5927..4f039381e50 100644
--- 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() {