rust-lang · adwinwhite · Aug 29, 2025 · Sep 1, 2025 · Sep 1, 2025
diff --git a/compiler/rustc_monomorphize/src/collector.rs b/compiler/rustc_monomorphize/src/collector.rs
@@ -473,6 +473,33 @@ fn collect_items_rec<'tcx>(
                 recursion_limit,
             ));
 
+            // Check whether the MIR body is malformed. Usually it's due to normalization overflow.
+            // FIXME: I assume that there are few type errors at post-analysis stage, but not
+            // entirely sure.
+            // Plenty of code paths later assume that everything can be normalized.
+            // Check normalization here to provide better diagnostics.
+            let body = tcx.instance_mir(instance.def);
+            let normalization_failed = body.local_decls.iter().any(|local| {
+                instance
+                    .try_instantiate_mir_and_normalize_erasing_regions(
+                        tcx,
+                        ty::TypingEnv::fully_monomorphized(),
+                        ty::EarlyBinder::bind(local.ty),
+                    )
+                    .is_err()
+            });
+            if normalization_failed {
+                let def_id = instance.def_id();
+                let def_span = tcx.def_span(def_id);
+                let def_path_str = tcx.def_path_str(def_id);
+                tcx.dcx().emit_fatal(RecursionLimit {
+                    span: starting_item.span,
+                    instance,
+                    def_span,
+                    def_path_str,
+                });
+            }
+
             rustc_data_structures::stack::ensure_sufficient_stack(|| {
                 let (used, mentioned) = tcx.items_of_instance((instance, mode));
                 used_items.extend(used.into_iter().copied());

diff --git a/compiler/rustc_traits/src/normalize_erasing_regions.rs b/compiler/rustc_traits/src/normalize_erasing_regions.rs
@@ -42,7 +42,18 @@ fn try_normalize_after_erasing_regions<'tcx, T: TypeFoldable<TyCtxt<'tcx>> + Par
             // us a test case.
             debug_assert_eq!(normalized_value, resolved_value);
             let erased = infcx.tcx.erase_regions(resolved_value);
-            debug_assert!(!erased.has_infer(), "{erased:?}");
+            if infcx.next_trait_solver() {
+                debug_assert!(!erased.has_infer(), "{erased:?}");
+            } else {
+                // The old solver returns an ty var with the failed obligation in case of
+                // selection error. And when the obligation is re-tried, the error should be
+                // reported. However in case of overflow error, the obligation may be fulfilled
+                // due to the original depth being dropped.
+                // In conclusion, overflow results in an unconstrained ty var.
+                if erased.has_infer() {
+                    return Err(NoSolution);
+                }
+            }
             Ok(erased)
         }
         Err(NoSolution) => Err(NoSolution),

diff --git a/tests/crashes/105275.rs → ...zation-overflow/recursion-issue-105275.rs b/tests/crashes/105275.rs → ...zation-overflow/recursion-issue-105275.rs
@@ -1,3 +1,4 @@
+//@ build-fail
 //@ known-bug: #105275
 //@ compile-flags: -Copt-level=0
 

diff --git a/tests/ui/codegen/normalization-overflow/recursion-issue-105275.stderr b/tests/ui/codegen/normalization-overflow/recursion-issue-105275.stderr
@@ -0,0 +1,14 @@
+error: reached the recursion limit while instantiating `encode_num::<&mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut Error>`
+  --> $DIR/recursion-issue-105275.rs:7:9
+   |
+LL |         encode_num(n / 16, &mut writer)?;
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: `encode_num` defined here
+  --> $DIR/recursion-issue-105275.rs:5:1
+   |
+LL | pub fn encode_num<Writer: ExampleWriter>(n: u32, mut writer: Writer) -> Result<(), Writer::Error> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
diff --git a/tests/crashes/105937.rs → ...zation-overflow/recursion-issue-105937.rs b/tests/crashes/105937.rs → ...zation-overflow/recursion-issue-105937.rs
@@ -1,3 +1,4 @@
+//@ build-fail
 //@ known-bug: #105937
 //@ compile-flags: -Copt-level=0
 

diff --git a/tests/ui/codegen/normalization-overflow/recursion-issue-105937.stderr b/tests/ui/codegen/normalization-overflow/recursion-issue-105937.stderr
@@ -0,0 +1,14 @@
+error: reached the recursion limit while instantiating `encode_num::<&mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut Error>`
+  --> $DIR/recursion-issue-105937.rs:7:9
+   |
+LL |         encode_num(n / 16, &mut writer)?;
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: `encode_num` defined here
+  --> $DIR/recursion-issue-105937.rs:5:1
+   |
+LL | pub fn encode_num<Writer: ExampleWriter>(n: u32, mut writer: Writer) -> Result<(), Writer::Error> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
diff --git a/tests/crashes/117696-2.rs → ...tion-overflow/recursion-issue-117696-2.rs b/tests/crashes/117696-2.rs → ...tion-overflow/recursion-issue-117696-2.rs
@@ -1,3 +1,4 @@
+//@ build-fail
 //@ known-bug: #117696
 //@ compile-flags: -Copt-level=0
 fn main() {

diff --git a/tests/ui/codegen/normalization-overflow/recursion-issue-117696-2.stderr b/tests/ui/codegen/normalization-overflow/recursion-issue-117696-2.stderr
@@ -0,0 +1,14 @@
+error: reached the recursion limit while instantiating `rec::<&mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut std::option::IntoIter<()>>`
+  --> $DIR/recursion-issue-117696-2.rs:12:9
+   |
+LL |         rec(&mut it);
+   |         ^^^^^^^^^^^^
+   |
+note: `rec` defined here
+  --> $DIR/recursion-issue-117696-2.rs:8:1
+   |
+LL | fn rec<T: Iterator>(mut it: T) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
diff --git a/tests/crashes/118590.rs → ...zation-overflow/recursion-issue-118590.rs b/tests/crashes/118590.rs → ...zation-overflow/recursion-issue-118590.rs
@@ -1,3 +1,4 @@
+//@ build-fail
 //@ known-bug: #118590
 
 fn main() {

diff --git a/tests/ui/codegen/normalization-overflow/recursion-issue-118590.stderr b/tests/ui/codegen/normalization-overflow/recursion-issue-118590.stderr
@@ -0,0 +1,11 @@
+error: reached the recursion limit while instantiating `<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<Peekable<Skip<std::iter::Empty<()>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> as Iterator>::peekable`
+  --> $DIR/recursion-issue-118590.rs:11:13
+   |
+LL |     recurse(nums.skip(42).peekable())
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: `peekable` defined here
+  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
+
+error: aborting due to 1 previous error
+
diff --git a/tests/crashes/122823.rs → ...zation-overflow/recursion-issue-122823.rs b/tests/crashes/122823.rs → ...zation-overflow/recursion-issue-122823.rs
@@ -1,3 +1,4 @@
+//@ build-fail
 //@ known-bug: #122823
 //@ compile-flags: -Copt-level=0
 // ignore-tidy-linelength

diff --git a/tests/ui/codegen/normalization-overflow/recursion-issue-122823.stderr b/tests/ui/codegen/normalization-overflow/recursion-issue-122823.stderr
@@ -0,0 +1,11 @@
+error: reached the recursion limit while instantiating `<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::vec::IntoIter<u64>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> as Iterator>::peekable`
+  --> $DIR/recursion-issue-122823.rs:44:38
+   |
+LL |         packets: decode_packets(&mut itr.take(0).peekable()),
+   |                                      ^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: `peekable` defined here
+  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
+
+error: aborting due to 1 previous error
+
diff --git a/tests/crashes/131342.rs → ...zation-overflow/recursion-issue-131342.rs b/tests/crashes/131342.rs → ...zation-overflow/recursion-issue-131342.rs
@@ -1,3 +1,4 @@
+//@ build-fail
 //@ known-bug: #131342
 
 fn main() {

diff --git a/tests/ui/codegen/normalization-overflow/recursion-issue-131342.stderr b/tests/ui/codegen/normalization-overflow/recursion-issue-131342.stderr
@@ -0,0 +1,11 @@
+error: reached the recursion limit while instantiating `<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut Peekable<&mut std::vec::IntoIter<u8>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> as Iterator>::peekable`
+  --> $DIR/recursion-issue-131342.rs:10:22
+   |
+LL |     let mut peeker = items.peekable();
+   |                      ^^^^^^^^^^^^^^^^
+   |
+note: `peekable` defined here
+  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
+
+error: aborting due to 1 previous error
+
diff --git a/tests/crashes/139659.rs → ...zation-overflow/recursion-issue-139659.rs b/tests/crashes/139659.rs → ...zation-overflow/recursion-issue-139659.rs
@@ -1,3 +1,4 @@
+//@ build-fail
 //@ known-bug: #139659
 //@compile-flags: -Cdebuginfo=2 -Copt-level=0 --crate-type lib
 trait Trait {

diff --git a/tests/ui/codegen/normalization-overflow/recursion-issue-139659.stderr b/tests/ui/codegen/normalization-overflow/recursion-issue-139659.stderr
@@ -0,0 +1,10 @@
+error: reached the recursion limit while instantiating `recurse`
+   |
+note: `recurse` defined here
+  --> $DIR/recursion-issue-139659.rs:27:1
+   |
+LL | pub fn recurse() -> impl Sized {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
diff --git a/tests/crashes/92004.rs → ...ization-overflow/recursion-issue-92004.rs b/tests/crashes/92004.rs → ...ization-overflow/recursion-issue-92004.rs
@@ -1,3 +1,4 @@
+//@ build-fail
 //@ known-bug: #102310
 //@ compile-flags: -Copt-level=0
 //@ edition:2021

diff --git a/tests/ui/codegen/normalization-overflow/recursion-issue-92004.stderr b/tests/ui/codegen/normalization-overflow/recursion-issue-92004.stderr
@@ -0,0 +1,11 @@
+error: reached the recursion limit while instantiating `<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::iter::Take<&mut Peekable<std::vec::IntoIter<u64>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> as Iterator>::peekable`
+  --> $DIR/recursion-issue-92004.rs:45:38
+   |
+LL |         packets: decode_packets(&mut itr.take(0).peekable()),
+   |                                      ^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: `peekable` defined here
+  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
+
+error: aborting due to 1 previous error
+
diff --git a/tests/crashes/92470.rs → ...ization-overflow/recursion-issue-92470.rs b/tests/crashes/92470.rs → ...ization-overflow/recursion-issue-92470.rs
@@ -1,3 +1,4 @@
+//@ build-fail
 //@ known-bug: #92470
 fn main() {
     encode(&mut EncoderImpl);

diff --git a/tests/ui/codegen/normalization-overflow/recursion-issue-92470.stderr b/tests/ui/codegen/normalization-overflow/recursion-issue-92470.stderr
@@ -0,0 +1,26 @@
+warning: function cannot return without recursing
+  --> $DIR/recursion-issue-92470.rs:13:1
+   |
+LL | fn encode<E: Encoder>(mut encoder: E) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing
+LL |     encoder.writer();
+LL |     encode(&mut encoder);
+   |     -------------------- recursive call site
+   |
+   = help: a `loop` may express intention better if this is on purpose
+   = note: `#[warn(unconditional_recursion)]` on by default
+
+error: reached the recursion limit while instantiating `encode::<&mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut EncoderImpl>`
+  --> $DIR/recursion-issue-92470.rs:15:5
+   |
+LL |     encode(&mut encoder);
+   |     ^^^^^^^^^^^^^^^^^^^^
+   |
+note: `encode` defined here
+  --> $DIR/recursion-issue-92470.rs:13:1
+   |
+LL | fn encode<E: Encoder>(mut encoder: E) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error; 1 warning emitted
+
diff --git a/tests/crashes/95134.rs → ...ization-overflow/recursion-issue-95134.rs b/tests/crashes/95134.rs → ...ization-overflow/recursion-issue-95134.rs
@@ -1,3 +1,4 @@
+//@ build-fail
 //@ known-bug: #95134
 //@ compile-flags: -Copt-level=0
 

diff --git a/tests/ui/codegen/normalization-overflow/recursion-issue-95134.stderr b/tests/ui/codegen/normalization-overflow/recursion-issue-95134.stderr
@@ -0,0 +1,14 @@
+error: reached the recursion limit while instantiating `encode_num::<&mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut EmptyWriter>`
+  --> $DIR/recursion-issue-95134.rs:7:9
+   |
+LL |         encode_num(n / 16, &mut writer)?;
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: `encode_num` defined here
+  --> $DIR/recursion-issue-95134.rs:5:1
+   |
+LL | pub fn encode_num<Writer: ExampleWriter>(n: u32, mut writer: Writer) -> Result<(), Writer::Error> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+