diff --git a/compiler/rustc_next_trait_solver/src/solve/search_graph.rs b/compiler/rustc_next_trait_solver/src/solve/search_graph.rs
index 109c8476ccb16..ea45d50969909 100644
--- a/compiler/rustc_next_trait_solver/src/solve/search_graph.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/search_graph.rs
@@ -99,19 +99,23 @@ where
         response_no_constraints(cx, input, Certainty::overflow(false))
     }
 
-    fn is_ambiguous_result(result: QueryResult<I>) -> bool {
-        result.is_ok_and(|response| {
-            has_no_inference_or_external_constraints(response)
+    fn is_ambiguous_result(result: QueryResult<I>) -> Option<Certainty> {
+        result.ok().and_then(|response| {
+            if has_no_inference_or_external_constraints(response)
                 && matches!(response.value.certainty, Certainty::Maybe { .. })
+            {
+                Some(response.value.certainty)
+            } else {
+                None
+            }
         })
     }
 
     fn propagate_ambiguity(
         cx: I,
         for_input: CanonicalInput<I>,
-        from_result: QueryResult<I>,
+        certainty: Certainty,
     ) -> QueryResult<I> {
-        let certainty = from_result.unwrap().value.certainty;
         response_no_constraints(cx, for_input, certainty)
     }
 
diff --git a/compiler/rustc_type_ir/src/interner.rs b/compiler/rustc_type_ir/src/interner.rs
index f933423197df3..4b6349e2f4269 100644
--- a/compiler/rustc_type_ir/src/interner.rs
+++ b/compiler/rustc_type_ir/src/interner.rs
@@ -11,7 +11,7 @@ use crate::inherent::*;
 use crate::ir_print::IrPrint;
 use crate::lang_items::{SolverAdtLangItem, SolverLangItem, SolverTraitLangItem};
 use crate::relate::Relate;
-use crate::solve::{CanonicalInput, ExternalConstraintsData, QueryResult, inspect};
+use crate::solve::{CanonicalInput, Certainty, ExternalConstraintsData, QueryResult, inspect};
 use crate::visit::{Flags, TypeVisitable};
 use crate::{self as ty, CanonicalParamEnvCacheEntry, search_graph};
 
@@ -550,6 +550,7 @@ impl<T, R, E> CollectAndApply<T, R> for Result<T, E> {
 impl<I: Interner> search_graph::Cx for I {
     type Input = CanonicalInput<I>;
     type Result = QueryResult<I>;
+    type AmbiguityInfo = Certainty;
 
     type DepNodeIndex = I::DepNodeIndex;
     type Tracked<T: Debug + Clone> = I::Tracked<T>;
diff --git a/compiler/rustc_type_ir/src/search_graph/mod.rs b/compiler/rustc_type_ir/src/search_graph/mod.rs
index 8a41c99aeaae1..b2a871a21149e 100644
--- a/compiler/rustc_type_ir/src/search_graph/mod.rs
+++ b/compiler/rustc_type_ir/src/search_graph/mod.rs
@@ -40,6 +40,7 @@ pub use global_cache::GlobalCache;
 pub trait Cx: Copy {
     type Input: Debug + Eq + Hash + Copy;
     type Result: Debug + Eq + Hash + Copy;
+    type AmbiguityInfo: Debug + Eq + Hash + Copy;
 
     type DepNodeIndex;
     type Tracked<T: Debug + Clone>: Debug;
@@ -96,11 +97,13 @@ pub trait Delegate: Sized {
         input: <Self::Cx as Cx>::Input,
     ) -> <Self::Cx as Cx>::Result;
 
-    fn is_ambiguous_result(result: <Self::Cx as Cx>::Result) -> bool;
+    fn is_ambiguous_result(
+        result: <Self::Cx as Cx>::Result,
+    ) -> Option<<Self::Cx as Cx>::AmbiguityInfo>;
     fn propagate_ambiguity(
         cx: Self::Cx,
         for_input: <Self::Cx as Cx>::Input,
-        from_result: <Self::Cx as Cx>::Result,
+        ambiguity_info: <Self::Cx as Cx>::AmbiguityInfo,
     ) -> <Self::Cx as Cx>::Result;
 
     fn compute_goal(
@@ -913,9 +916,9 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
 /// heads from the stack. This may not necessarily mean that we've actually
 /// reached a fixpoint for that cycle head, which impacts the way we rebase
 /// provisional cache entries.
-enum RebaseReason {
+enum RebaseReason<X: Cx> {
     NoCycleUsages,
-    Ambiguity,
+    Ambiguity(X::AmbiguityInfo),
     Overflow,
     /// We've actually reached a fixpoint.
     ///
@@ -951,7 +954,7 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D, X> {
         &mut self,
         cx: X,
         stack_entry: &StackEntry<X>,
-        rebase_reason: RebaseReason,
+        rebase_reason: RebaseReason<X>,
     ) {
         let popped_head_index = self.stack.next_index();
         #[allow(rustc::potential_query_instability)]
@@ -969,10 +972,6 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D, X> {
                     return true;
                 };
 
-                let Some(new_highest_head_index) = heads.opt_highest_cycle_head_index() else {
-                    return false;
-                };
-
                 // We're rebasing an entry `e` over a head `p`. This head
                 // has a number of own heads `h` it depends on.
                 //
@@ -1033,8 +1032,8 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D, X> {
                         // is not actually equal to the final provisional result. We
                         // need to discard the provisional cache entry in this case.
                         RebaseReason::NoCycleUsages => return false,
-                        RebaseReason::Ambiguity => {
-                            *result = D::propagate_ambiguity(cx, input, *result);
+                        RebaseReason::Ambiguity(info) => {
+                            *result = D::propagate_ambiguity(cx, input, info);
                         }
                         RebaseReason::Overflow => *result = D::fixpoint_overflow_result(cx, input),
                         RebaseReason::ReachedFixpoint(None) => {}
@@ -1046,6 +1045,10 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D, X> {
                     };
                 }
 
+                let Some(new_highest_head_index) = heads.opt_highest_cycle_head_index() else {
+                    return false;
+                };
+
                 // We now care about the path from the next highest cycle head to the
                 // provisional cache entry.
                 *path_from_head = path_from_head.extend(Self::cycle_path_kind(
@@ -1268,6 +1271,7 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D, X> {
     }
 
     /// Whether we've reached a fixpoint when evaluating a cycle head.
+    #[instrument(level = "trace", skip(self, stack_entry), ret)]
     fn reached_fixpoint(
         &mut self,
         stack_entry: &StackEntry<X>,
@@ -1355,8 +1359,12 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D, X> {
             // As we only get to this branch if we haven't yet reached a fixpoint,
             // we also taint all provisional cache entries which depend on the
             // current goal.
-            if D::is_ambiguous_result(result) {
-                self.rebase_provisional_cache_entries(cx, &stack_entry, RebaseReason::Ambiguity);
+            if let Some(info) = D::is_ambiguous_result(result) {
+                self.rebase_provisional_cache_entries(
+                    cx,
+                    &stack_entry,
+                    RebaseReason::Ambiguity(info),
+                );
                 return EvaluationResult::finalize(stack_entry, encountered_overflow, result);
             };
 
diff --git a/library/proc_macro/src/bridge/client.rs b/library/proc_macro/src/bridge/client.rs
index 92558f2b7d9cc..bdaa865a998d6 100644
--- a/library/proc_macro/src/bridge/client.rs
+++ b/library/proc_macro/src/bridge/client.rs
@@ -58,7 +58,7 @@ macro_rules! define_client_handles {
                 }
             }
 
-            impl<S> DecodeMut<'_, '_, S> for $oty {
+            impl<S> Decode<'_, '_, S> for $oty {
                 fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
                     $oty {
                         handle: handle::Handle::decode(r, s),
@@ -82,7 +82,7 @@ macro_rules! define_client_handles {
                 }
             }
 
-            impl<S> DecodeMut<'_, '_, S> for $ity {
+            impl<S> Decode<'_, '_, S> for $ity {
                 fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
                     $ity {
                         handle: handle::Handle::decode(r, s),
@@ -276,7 +276,7 @@ fn maybe_install_panic_hook(force_show_panics: bool) {
 /// Client-side helper for handling client panics, entering the bridge,
 /// deserializing input and serializing output.
 // FIXME(eddyb) maybe replace `Bridge::enter` with this?
-fn run_client<A: for<'a, 's> DecodeMut<'a, 's, ()>, R: Encode<()>>(
+fn run_client<A: for<'a, 's> Decode<'a, 's, ()>, R: Encode<()>>(
     config: BridgeConfig<'_>,
     f: impl FnOnce(A) -> R,
 ) -> Buffer {
diff --git a/library/proc_macro/src/bridge/mod.rs b/library/proc_macro/src/bridge/mod.rs
index 582c43c78fcbb..b0ee9c0cc3027 100644
--- a/library/proc_macro/src/bridge/mod.rs
+++ b/library/proc_macro/src/bridge/mod.rs
@@ -143,7 +143,7 @@ mod symbol;
 
 use buffer::Buffer;
 pub use rpc::PanicMessage;
-use rpc::{DecodeMut, Encode, Reader, Writer};
+use rpc::{Decode, Encode, Reader, Writer};
 
 /// Configuration for establishing an active connection between a server and a
 /// client.  The server creates the bridge config (`run_server` in `server.rs`),
@@ -168,7 +168,7 @@ impl !Sync for BridgeConfig<'_> {}
 #[forbid(unsafe_code)]
 #[allow(non_camel_case_types)]
 mod api_tags {
-    use super::rpc::{DecodeMut, Encode, Reader, Writer};
+    use super::rpc::{Decode, Encode, Reader, Writer};
 
     macro_rules! declare_tags {
         ($($name:ident {
diff --git a/library/proc_macro/src/bridge/rpc.rs b/library/proc_macro/src/bridge/rpc.rs
index 7f4f5fc3a97d5..ed67674a74ab7 100644
--- a/library/proc_macro/src/bridge/rpc.rs
+++ b/library/proc_macro/src/bridge/rpc.rs
@@ -12,7 +12,7 @@ pub(super) trait Encode<S>: Sized {
 
 pub(super) type Reader<'a> = &'a [u8];
 
-pub(super) trait DecodeMut<'a, 's, S>: Sized {
+pub(super) trait Decode<'a, 's, S>: Sized {
     fn decode(r: &mut Reader<'a>, s: &'s mut S) -> Self;
 }
 
@@ -24,7 +24,7 @@ macro_rules! rpc_encode_decode {
             }
         }
 
-        impl<S> DecodeMut<'_, '_, S> for $ty {
+        impl<S> Decode<'_, '_, S> for $ty {
             fn decode(r: &mut Reader<'_>, _: &mut S) -> Self {
                 const N: usize = size_of::<$ty>();
 
@@ -43,12 +43,12 @@ macro_rules! rpc_encode_decode {
             }
         }
 
-        impl<'a, S, $($($T: for<'s> DecodeMut<'a, 's, S>),+)?> DecodeMut<'a, '_, S>
+        impl<'a, S, $($($T: for<'s> Decode<'a, 's, S>),+)?> Decode<'a, '_, S>
             for $name $(<$($T),+>)?
         {
             fn decode(r: &mut Reader<'a>, s: &mut S) -> Self {
                 $name {
-                    $($field: DecodeMut::decode(r, s)),*
+                    $($field: Decode::decode(r, s)),*
                 }
             }
         }
@@ -58,23 +58,18 @@ macro_rules! rpc_encode_decode {
             fn encode(self, w: &mut Writer, s: &mut S) {
                 // HACK(eddyb): `Tag` enum duplicated between the
                 // two impls as there's no other place to stash it.
-                #[allow(non_upper_case_globals)]
-                mod tag {
-                    #[repr(u8)] enum Tag { $($variant),* }
-
-                    $(pub(crate) const $variant: u8 = Tag::$variant as u8;)*
-                }
+                #[repr(u8)] enum Tag { $($variant),* }
 
                 match self {
                     $($name::$variant $(($field))* => {
-                        tag::$variant.encode(w, s);
+                        (Tag::$variant as u8).encode(w, s);
                         $($field.encode(w, s);)*
                     })*
                 }
             }
         }
 
-        impl<'a, S, $($($T: for<'s> DecodeMut<'a, 's, S>),+)?> DecodeMut<'a, '_, S>
+        impl<'a, S, $($($T: for<'s> Decode<'a, 's, S>),+)?> Decode<'a, '_, S>
             for $name $(<$($T),+>)?
         {
             fn decode(r: &mut Reader<'a>, s: &mut S) -> Self {
@@ -89,7 +84,7 @@ macro_rules! rpc_encode_decode {
 
                 match u8::decode(r, s) {
                     $(tag::$variant => {
-                        $(let $field = DecodeMut::decode(r, s);)*
+                        $(let $field = Decode::decode(r, s);)*
                         $name::$variant $(($field))*
                     })*
                     _ => unreachable!(),
@@ -103,7 +98,7 @@ impl<S> Encode<S> for () {
     fn encode(self, _: &mut Writer, _: &mut S) {}
 }
 
-impl<S> DecodeMut<'_, '_, S> for () {
+impl<S> Decode<'_, '_, S> for () {
     fn decode(_: &mut Reader<'_>, _: &mut S) -> Self {}
 }
 
@@ -113,7 +108,7 @@ impl<S> Encode<S> for u8 {
     }
 }
 
-impl<S> DecodeMut<'_, '_, S> for u8 {
+impl<S> Decode<'_, '_, S> for u8 {
     fn decode(r: &mut Reader<'_>, _: &mut S) -> Self {
         let x = r[0];
         *r = &r[1..];
@@ -130,7 +125,7 @@ impl<S> Encode<S> for bool {
     }
 }
 
-impl<S> DecodeMut<'_, '_, S> for bool {
+impl<S> Decode<'_, '_, S> for bool {
     fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
         match u8::decode(r, s) {
             0 => false,
@@ -146,7 +141,7 @@ impl<S> Encode<S> for char {
     }
 }
 
-impl<S> DecodeMut<'_, '_, S> for char {
+impl<S> Decode<'_, '_, S> for char {
     fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
         char::from_u32(u32::decode(r, s)).unwrap()
     }
@@ -158,7 +153,7 @@ impl<S> Encode<S> for NonZero<u32> {
     }
 }
 
-impl<S> DecodeMut<'_, '_, S> for NonZero<u32> {
+impl<S> Decode<'_, '_, S> for NonZero<u32> {
     fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
         Self::new(u32::decode(r, s)).unwrap()
     }
@@ -171,11 +166,11 @@ impl<S, A: Encode<S>, B: Encode<S>> Encode<S> for (A, B) {
     }
 }
 
-impl<'a, S, A: for<'s> DecodeMut<'a, 's, S>, B: for<'s> DecodeMut<'a, 's, S>> DecodeMut<'a, '_, S>
+impl<'a, S, A: for<'s> Decode<'a, 's, S>, B: for<'s> Decode<'a, 's, S>> Decode<'a, '_, S>
     for (A, B)
 {
     fn decode(r: &mut Reader<'a>, s: &mut S) -> Self {
-        (DecodeMut::decode(r, s), DecodeMut::decode(r, s))
+        (Decode::decode(r, s), Decode::decode(r, s))
     }
 }
 
@@ -186,7 +181,7 @@ impl<S> Encode<S> for &[u8] {
     }
 }
 
-impl<'a, S> DecodeMut<'a, '_, S> for &'a [u8] {
+impl<'a, S> Decode<'a, '_, S> for &'a [u8] {
     fn decode(r: &mut Reader<'a>, s: &mut S) -> Self {
         let len = usize::decode(r, s);
         let xs = &r[..len];
@@ -201,7 +196,7 @@ impl<S> Encode<S> for &str {
     }
 }
 
-impl<'a, S> DecodeMut<'a, '_, S> for &'a str {
+impl<'a, S> Decode<'a, '_, S> for &'a str {
     fn decode(r: &mut Reader<'a>, s: &mut S) -> Self {
         str::from_utf8(<&[u8]>::decode(r, s)).unwrap()
     }
@@ -213,7 +208,7 @@ impl<S> Encode<S> for String {
     }
 }
 
-impl<S> DecodeMut<'_, '_, S> for String {
+impl<S> Decode<'_, '_, S> for String {
     fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
         <&str>::decode(r, s).to_string()
     }
@@ -228,7 +223,7 @@ impl<S, T: Encode<S>> Encode<S> for Vec<T> {
     }
 }
 
-impl<'a, S, T: for<'s> DecodeMut<'a, 's, S>> DecodeMut<'a, '_, S> for Vec<T> {
+impl<'a, S, T: for<'s> Decode<'a, 's, S>> Decode<'a, '_, S> for Vec<T> {
     fn decode(r: &mut Reader<'a>, s: &mut S) -> Self {
         let len = usize::decode(r, s);
         let mut vec = Vec::with_capacity(len);
@@ -288,7 +283,7 @@ impl<S> Encode<S> for PanicMessage {
     }
 }
 
-impl<S> DecodeMut<'_, '_, S> for PanicMessage {
+impl<S> Decode<'_, '_, S> for PanicMessage {
     fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
         match Option::<String>::decode(r, s) {
             Some(s) => PanicMessage::String(s),
diff --git a/library/proc_macro/src/bridge/selfless_reify.rs b/library/proc_macro/src/bridge/selfless_reify.rs
index b06434a5ffee2..a53550e0b9e0c 100644
--- a/library/proc_macro/src/bridge/selfless_reify.rs
+++ b/library/proc_macro/src/bridge/selfless_reify.rs
@@ -50,7 +50,7 @@ macro_rules! define_reify_functions {
         >(f: F) -> $(extern $abi)? fn($($arg_ty),*) -> $ret_ty {
             // FIXME(eddyb) describe the `F` type (e.g. via `type_name::<F>`) once panic
             // formatting becomes possible in `const fn`.
-            assert!(size_of::<F>() == 0, "selfless_reify: closure must be zero-sized");
+            const { assert!(size_of::<F>() == 0, "selfless_reify: closure must be zero-sized"); }
 
             $(extern $abi)? fn wrapper<
                 $($($param,)*)?
diff --git a/library/proc_macro/src/bridge/server.rs b/library/proc_macro/src/bridge/server.rs
index 2850e1099b700..e9ef26c07f24f 100644
--- a/library/proc_macro/src/bridge/server.rs
+++ b/library/proc_macro/src/bridge/server.rs
@@ -32,7 +32,7 @@ macro_rules! define_server_handles {
                 }
             }
 
-            impl<S: Types> DecodeMut<'_, '_, HandleStore<MarkedTypes<S>>>
+            impl<S: Types> Decode<'_, '_, HandleStore<MarkedTypes<S>>>
                 for Marked<S::$oty, client::$oty>
             {
                 fn decode(r: &mut Reader<'_>, s: &mut HandleStore<MarkedTypes<S>>) -> Self {
@@ -40,7 +40,7 @@ macro_rules! define_server_handles {
                 }
             }
 
-            impl<'s, S: Types> DecodeMut<'_, 's, HandleStore<MarkedTypes<S>>>
+            impl<'s, S: Types> Decode<'_, 's, HandleStore<MarkedTypes<S>>>
                 for &'s Marked<S::$oty, client::$oty>
             {
                 fn decode(r: &mut Reader<'_>, s: &'s mut HandleStore<MarkedTypes<S>>) -> Self {
@@ -48,7 +48,7 @@ macro_rules! define_server_handles {
                 }
             }
 
-            impl<'s, S: Types> DecodeMut<'_, 's, HandleStore<MarkedTypes<S>>>
+            impl<'s, S: Types> Decode<'_, 's, HandleStore<MarkedTypes<S>>>
                 for &'s mut Marked<S::$oty, client::$oty>
             {
                 fn decode(
@@ -67,7 +67,7 @@ macro_rules! define_server_handles {
                 }
             }
 
-            impl<S: Types> DecodeMut<'_, '_, HandleStore<MarkedTypes<S>>>
+            impl<S: Types> Decode<'_, '_, HandleStore<MarkedTypes<S>>>
                 for Marked<S::$ity, client::$ity>
             {
                 fn decode(r: &mut Reader<'_>, s: &mut HandleStore<MarkedTypes<S>>) -> Self {
@@ -355,7 +355,7 @@ pub trait MessagePipe<T>: Sized {
 fn run_server<
     S: Server,
     I: Encode<HandleStore<MarkedTypes<S>>>,
-    O: for<'a, 's> DecodeMut<'a, 's, HandleStore<MarkedTypes<S>>>,
+    O: for<'a, 's> Decode<'a, 's, HandleStore<MarkedTypes<S>>>,
 >(
     strategy: &impl ExecutionStrategy,
     handle_counters: &'static client::HandleCounters,
diff --git a/library/proc_macro/src/bridge/symbol.rs b/library/proc_macro/src/bridge/symbol.rs
index eb7d30f9a6cc9..0d6a725fddd98 100644
--- a/library/proc_macro/src/bridge/symbol.rs
+++ b/library/proc_macro/src/bridge/symbol.rs
@@ -102,7 +102,7 @@ impl<S> Encode<S> for Symbol {
     }
 }
 
-impl<S: server::Server> DecodeMut<'_, '_, server::HandleStore<server::MarkedTypes<S>>>
+impl<S: server::Server> Decode<'_, '_, server::HandleStore<server::MarkedTypes<S>>>
     for Marked<S::Symbol, Symbol>
 {
     fn decode(r: &mut Reader<'_>, s: &mut server::HandleStore<server::MarkedTypes<S>>) -> Self {
@@ -118,7 +118,7 @@ impl<S: server::Server> Encode<server::HandleStore<server::MarkedTypes<S>>>
     }
 }
 
-impl<S> DecodeMut<'_, '_, S> for Symbol {
+impl<S> Decode<'_, '_, S> for Symbol {
     fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
         Symbol::new(<&str>::decode(r, s))
     }
diff --git a/library/std/src/fs.rs b/library/std/src/fs.rs
index 28b2c7173d321..b548eb4939d42 100644
--- a/library/std/src/fs.rs
+++ b/library/std/src/fs.rs
@@ -387,6 +387,87 @@ pub fn write<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> io::Result
     inner(path.as_ref(), contents.as_ref())
 }
 
+/// Changes the timestamps of the file or directory at the specified path.
+///
+/// This function will attempt to set the access and modification times
+/// to the times specified. If the path refers to a symbolic link, this function
+/// will follow the link and change the timestamps of the target file.
+///
+/// # Platform-specific behavior
+///
+/// This function currently corresponds to the `utimensat` function on Unix platforms, the
+/// `setattrlist` function on Apple platforms, and the `SetFileTime` function on Windows.
+///
+/// # Errors
+///
+/// This function will return an error if the user lacks permission to change timestamps on the
+/// target file or symlink. It may also return an error if the OS does not support it.
+///
+/// # Examples
+///
+/// ```no_run
+/// #![feature(fs_set_times)]
+/// use std::fs::{self, FileTimes};
+/// use std::time::SystemTime;
+///
+/// fn main() -> std::io::Result<()> {
+///     let now = SystemTime::now();
+///     let times = FileTimes::new()
+///         .set_accessed(now)
+///         .set_modified(now);
+///     fs::set_times("foo.txt", times)?;
+///     Ok(())
+/// }
+/// ```
+#[unstable(feature = "fs_set_times", issue = "147455")]
+#[doc(alias = "utimens")]
+#[doc(alias = "utimes")]
+#[doc(alias = "utime")]
+pub fn set_times<P: AsRef<Path>>(path: P, times: FileTimes) -> io::Result<()> {
+    fs_imp::set_times(path.as_ref(), times.0)
+}
+
+/// Changes the timestamps of the file or symlink at the specified path.
+///
+/// This function will attempt to set the access and modification times
+/// to the times specified. Differ from `set_times`, if the path refers to a symbolic link,
+/// this function will change the timestamps of the symlink itself, not the target file.
+///
+/// # Platform-specific behavior
+///
+/// This function currently corresponds to the `utimensat` function with `AT_SYMLINK_NOFOLLOW` on
+/// Unix platforms, the `setattrlist` function with `FSOPT_NOFOLLOW` on Apple platforms, and the
+/// `SetFileTime` function on Windows.
+///
+/// # Errors
+///
+/// This function will return an error if the user lacks permission to change timestamps on the
+/// target file or symlink. It may also return an error if the OS does not support it.
+///
+/// # Examples
+///
+/// ```no_run
+/// #![feature(fs_set_times)]
+/// use std::fs::{self, FileTimes};
+/// use std::time::SystemTime;
+///
+/// fn main() -> std::io::Result<()> {
+///     let now = SystemTime::now();
+///     let times = FileTimes::new()
+///         .set_accessed(now)
+///         .set_modified(now);
+///     fs::set_times_nofollow("symlink.txt", times)?;
+///     Ok(())
+/// }
+/// ```
+#[unstable(feature = "fs_set_times", issue = "147455")]
+#[doc(alias = "utimensat")]
+#[doc(alias = "lutimens")]
+#[doc(alias = "lutimes")]
+pub fn set_times_nofollow<P: AsRef<Path>>(path: P, times: FileTimes) -> io::Result<()> {
+    fs_imp::set_times_nofollow(path.as_ref(), times.0)
+}
+
 #[stable(feature = "file_lock", since = "1.89.0")]
 impl error::Error for TryLockError {}
 
diff --git a/library/std/src/fs/tests.rs b/library/std/src/fs/tests.rs
index f8dfb0d633400..4d67ba9248998 100644
--- a/library/std/src/fs/tests.rs
+++ b/library/std/src/fs/tests.rs
@@ -2226,3 +2226,222 @@ fn test_open_options_invalid_combinations() {
     assert_eq!(err.kind(), ErrorKind::InvalidInput);
     assert_eq!(err.to_string(), "must specify at least one of read, write, or append access");
 }
+
+#[test]
+fn test_fs_set_times() {
+    #[cfg(target_vendor = "apple")]
+    use crate::os::darwin::fs::FileTimesExt;
+    #[cfg(windows)]
+    use crate::os::windows::fs::FileTimesExt;
+
+    let tmp = tmpdir();
+    let path = tmp.join("foo");
+    File::create(&path).unwrap();
+
+    let mut times = FileTimes::new();
+    let accessed = SystemTime::UNIX_EPOCH + Duration::from_secs(12345);
+    let modified = SystemTime::UNIX_EPOCH + Duration::from_secs(54321);
+    times = times.set_accessed(accessed).set_modified(modified);
+
+    #[cfg(any(windows, target_vendor = "apple"))]
+    let created = SystemTime::UNIX_EPOCH + Duration::from_secs(32123);
+    #[cfg(any(windows, target_vendor = "apple"))]
+    {
+        times = times.set_created(created);
+    }
+
+    match fs::set_times(&path, times) {
+        // Allow unsupported errors on platforms which don't support setting times.
+        #[cfg(not(any(
+            windows,
+            all(
+                unix,
+                not(any(
+                    target_os = "android",
+                    target_os = "redox",
+                    target_os = "espidf",
+                    target_os = "horizon"
+                ))
+            )
+        )))]
+        Err(e) if e.kind() == ErrorKind::Unsupported => return,
+        Err(e) => panic!("error setting file times: {e:?}"),
+        Ok(_) => {}
+    }
+
+    let metadata = fs::metadata(&path).unwrap();
+    assert_eq!(metadata.accessed().unwrap(), accessed);
+    assert_eq!(metadata.modified().unwrap(), modified);
+    #[cfg(any(windows, target_vendor = "apple"))]
+    {
+        assert_eq!(metadata.created().unwrap(), created);
+    }
+}
+
+#[test]
+fn test_fs_set_times_follows_symlink() {
+    #[cfg(target_vendor = "apple")]
+    use crate::os::darwin::fs::FileTimesExt;
+    #[cfg(windows)]
+    use crate::os::windows::fs::FileTimesExt;
+
+    let tmp = tmpdir();
+
+    // Create a target file
+    let target = tmp.join("target");
+    File::create(&target).unwrap();
+
+    // Create a symlink to the target
+    #[cfg(unix)]
+    let link = tmp.join("link");
+    #[cfg(unix)]
+    crate::os::unix::fs::symlink(&target, &link).unwrap();
+
+    #[cfg(windows)]
+    let link = tmp.join("link.txt");
+    #[cfg(windows)]
+    crate::os::windows::fs::symlink_file(&target, &link).unwrap();
+
+    // Get the symlink's own modified time BEFORE calling set_times (to compare later)
+    // We don't check accessed time because reading metadata may update atime on some platforms.
+    let link_metadata_before = fs::symlink_metadata(&link).unwrap();
+    let link_modified_before = link_metadata_before.modified().unwrap();
+
+    let mut times = FileTimes::new();
+    let accessed = SystemTime::UNIX_EPOCH + Duration::from_secs(12345);
+    let modified = SystemTime::UNIX_EPOCH + Duration::from_secs(54321);
+    times = times.set_accessed(accessed).set_modified(modified);
+
+    #[cfg(any(windows, target_vendor = "apple"))]
+    let created = SystemTime::UNIX_EPOCH + Duration::from_secs(32123);
+    #[cfg(any(windows, target_vendor = "apple"))]
+    {
+        times = times.set_created(created);
+    }
+
+    // Call fs::set_times on the symlink - it should follow the link and modify the target
+    match fs::set_times(&link, times) {
+        // Allow unsupported errors on platforms which don't support setting times.
+        #[cfg(not(any(
+            windows,
+            all(
+                unix,
+                not(any(
+                    target_os = "android",
+                    target_os = "redox",
+                    target_os = "espidf",
+                    target_os = "horizon"
+                ))
+            )
+        )))]
+        Err(e) if e.kind() == ErrorKind::Unsupported => return,
+        Err(e) => panic!("error setting file times through symlink: {e:?}"),
+        Ok(_) => {}
+    }
+
+    // Verify that the TARGET file's times were changed (following the symlink)
+    let target_metadata = fs::metadata(&target).unwrap();
+    assert_eq!(
+        target_metadata.accessed().unwrap(),
+        accessed,
+        "target file accessed time should match"
+    );
+    assert_eq!(
+        target_metadata.modified().unwrap(),
+        modified,
+        "target file modified time should match"
+    );
+    #[cfg(any(windows, target_vendor = "apple"))]
+    {
+        assert_eq!(
+            target_metadata.created().unwrap(),
+            created,
+            "target file created time should match"
+        );
+    }
+
+    // Also verify through the symlink (fs::metadata follows symlinks)
+    let link_followed_metadata = fs::metadata(&link).unwrap();
+    assert_eq!(link_followed_metadata.accessed().unwrap(), accessed);
+    assert_eq!(link_followed_metadata.modified().unwrap(), modified);
+
+    // Verify that the SYMLINK ITSELF was NOT modified
+    // Note: We only check modified time, not accessed time, because reading the symlink
+    // metadata may update its atime on some platforms (e.g., Linux).
+    let link_metadata_after = fs::symlink_metadata(&link).unwrap();
+    assert_eq!(
+        link_metadata_after.modified().unwrap(),
+        link_modified_before,
+        "symlink's own modified time should not change"
+    );
+}
+
+#[test]
+fn test_fs_set_times_nofollow() {
+    #[cfg(target_vendor = "apple")]
+    use crate::os::darwin::fs::FileTimesExt;
+    #[cfg(windows)]
+    use crate::os::windows::fs::FileTimesExt;
+
+    let tmp = tmpdir();
+
+    // Create a target file and a symlink to it
+    let target = tmp.join("target");
+    File::create(&target).unwrap();
+
+    #[cfg(unix)]
+    let link = tmp.join("link");
+    #[cfg(unix)]
+    crate::os::unix::fs::symlink(&target, &link).unwrap();
+
+    #[cfg(windows)]
+    let link = tmp.join("link.txt");
+    #[cfg(windows)]
+    crate::os::windows::fs::symlink_file(&target, &link).unwrap();
+
+    let mut times = FileTimes::new();
+    let accessed = SystemTime::UNIX_EPOCH + Duration::from_secs(11111);
+    let modified = SystemTime::UNIX_EPOCH + Duration::from_secs(22222);
+    times = times.set_accessed(accessed).set_modified(modified);
+
+    #[cfg(any(windows, target_vendor = "apple"))]
+    let created = SystemTime::UNIX_EPOCH + Duration::from_secs(33333);
+    #[cfg(any(windows, target_vendor = "apple"))]
+    {
+        times = times.set_created(created);
+    }
+
+    // Set times on the symlink itself (not following it)
+    match fs::set_times_nofollow(&link, times) {
+        // Allow unsupported errors on platforms which don't support setting times.
+        #[cfg(not(any(
+            windows,
+            all(
+                unix,
+                not(any(
+                    target_os = "android",
+                    target_os = "redox",
+                    target_os = "espidf",
+                    target_os = "horizon"
+                ))
+            )
+        )))]
+        Err(e) if e.kind() == ErrorKind::Unsupported => return,
+        Err(e) => panic!("error setting symlink times: {e:?}"),
+        Ok(_) => {}
+    }
+
+    // Read symlink metadata (without following)
+    let metadata = fs::symlink_metadata(&link).unwrap();
+    assert_eq!(metadata.accessed().unwrap(), accessed);
+    assert_eq!(metadata.modified().unwrap(), modified);
+    #[cfg(any(windows, target_vendor = "apple"))]
+    {
+        assert_eq!(metadata.created().unwrap(), created);
+    }
+
+    // Verify that the target file's times were NOT changed
+    let target_metadata = fs::metadata(&target).unwrap();
+    assert_ne!(target_metadata.accessed().unwrap(), accessed);
+    assert_ne!(target_metadata.modified().unwrap(), modified);
+}
diff --git a/library/std/src/sys/fs/hermit.rs b/library/std/src/sys/fs/hermit.rs
index 175d919c289dd..21235bcfbd8c5 100644
--- a/library/std/src/sys/fs/hermit.rs
+++ b/library/std/src/sys/fs/hermit.rs
@@ -566,6 +566,14 @@ pub fn set_perm(_p: &Path, _perm: FilePermissions) -> io::Result<()> {
     Err(Error::from_raw_os_error(22))
 }
 
+pub fn set_times(_p: &Path, _times: FileTimes) -> io::Result<()> {
+    Err(Error::from_raw_os_error(22))
+}
+
+pub fn set_times_nofollow(_p: &Path, _times: FileTimes) -> io::Result<()> {
+    Err(Error::from_raw_os_error(22))
+}
+
 pub fn rmdir(path: &Path) -> io::Result<()> {
     run_path_with_cstr(path, &|path| cvt(unsafe { hermit_abi::rmdir(path.as_ptr()) }).map(|_| ()))
 }
diff --git a/library/std/src/sys/fs/mod.rs b/library/std/src/sys/fs/mod.rs
index 64f5a6b36d3db..b498f9cb7ea72 100644
--- a/library/std/src/sys/fs/mod.rs
+++ b/library/std/src/sys/fs/mod.rs
@@ -161,3 +161,11 @@ pub fn exists(path: &Path) -> io::Result<bool> {
     #[cfg(windows)]
     with_native_path(path, &imp::exists)
 }
+
+pub fn set_times(path: &Path, times: FileTimes) -> io::Result<()> {
+    with_native_path(path, &|path| imp::set_times(path, times.clone()))
+}
+
+pub fn set_times_nofollow(path: &Path, times: FileTimes) -> io::Result<()> {
+    with_native_path(path, &|path| imp::set_times_nofollow(path, times.clone()))
+}
diff --git a/library/std/src/sys/fs/solid.rs b/library/std/src/sys/fs/solid.rs
index 808a95829114e..f6d5d3b784d3b 100644
--- a/library/std/src/sys/fs/solid.rs
+++ b/library/std/src/sys/fs/solid.rs
@@ -538,6 +538,14 @@ pub fn set_perm(p: &Path, perm: FilePermissions) -> io::Result<()> {
     Ok(())
 }
 
+pub fn set_times(_p: &Path, _times: FileTimes) -> io::Result<()> {
+    unsupported()
+}
+
+pub fn set_times_nofollow(_p: &Path, _times: FileTimes) -> io::Result<()> {
+    unsupported()
+}
+
 pub fn rmdir(p: &Path) -> io::Result<()> {
     if stat(p)?.file_type().is_dir() {
         error::SolidError::err_if_negative(unsafe { abi::SOLID_FS_Unlink(cstr(p)?.as_ptr()) })
diff --git a/library/std/src/sys/fs/uefi.rs b/library/std/src/sys/fs/uefi.rs
index 5763d7862f5ae..e4e7274ae8cb3 100644
--- a/library/std/src/sys/fs/uefi.rs
+++ b/library/std/src/sys/fs/uefi.rs
@@ -333,6 +333,14 @@ pub fn set_perm(_p: &Path, _perm: FilePermissions) -> io::Result<()> {
     unsupported()
 }
 
+pub fn set_times(_p: &Path, _times: FileTimes) -> io::Result<()> {
+    unsupported()
+}
+
+pub fn set_times_nofollow(_p: &Path, _times: FileTimes) -> io::Result<()> {
+    unsupported()
+}
+
 pub fn rmdir(_p: &Path) -> io::Result<()> {
     unsupported()
 }
diff --git a/library/std/src/sys/fs/unix.rs b/library/std/src/sys/fs/unix.rs
index 33a1e7ff5e40e..51849a31f61b5 100644
--- a/library/std/src/sys/fs/unix.rs
+++ b/library/std/src/sys/fs/unix.rs
@@ -1604,24 +1604,6 @@ impl File {
     }
 
     pub fn set_times(&self, times: FileTimes) -> io::Result<()> {
-        #[cfg(not(any(
-            target_os = "redox",
-            target_os = "espidf",
-            target_os = "horizon",
-            target_os = "nuttx",
-        )))]
-        let to_timespec = |time: Option<SystemTime>| match time {
-            Some(time) if let Some(ts) = time.t.to_timespec() => Ok(ts),
-            Some(time) if time > crate::sys::time::UNIX_EPOCH => Err(io::const_error!(
-                io::ErrorKind::InvalidInput,
-                "timestamp is too large to set as a file time",
-            )),
-            Some(_) => Err(io::const_error!(
-                io::ErrorKind::InvalidInput,
-                "timestamp is too small to set as a file time",
-            )),
-            None => Ok(libc::timespec { tv_sec: 0, tv_nsec: libc::UTIME_OMIT as _ }),
-        };
         cfg_select! {
             any(target_os = "redox", target_os = "espidf", target_os = "horizon", target_os = "nuttx") => {
                 // Redox doesn't appear to support `UTIME_OMIT`.
@@ -1634,36 +1616,18 @@ impl File {
                 ))
             }
             target_vendor = "apple" => {
-                let mut buf = [mem::MaybeUninit::<libc::timespec>::uninit(); 3];
-                let mut num_times = 0;
-                let mut attrlist: libc::attrlist = unsafe { mem::zeroed() };
-                attrlist.bitmapcount = libc::ATTR_BIT_MAP_COUNT;
-                if times.created.is_some() {
-                    buf[num_times].write(to_timespec(times.created)?);
-                    num_times += 1;
-                    attrlist.commonattr |= libc::ATTR_CMN_CRTIME;
-                }
-                if times.modified.is_some() {
-                    buf[num_times].write(to_timespec(times.modified)?);
-                    num_times += 1;
-                    attrlist.commonattr |= libc::ATTR_CMN_MODTIME;
-                }
-                if times.accessed.is_some() {
-                    buf[num_times].write(to_timespec(times.accessed)?);
-                    num_times += 1;
-                    attrlist.commonattr |= libc::ATTR_CMN_ACCTIME;
-                }
+                let ta = TimesAttrlist::from_times(&times)?;
                 cvt(unsafe { libc::fsetattrlist(
                     self.as_raw_fd(),
-                    (&raw const attrlist).cast::<libc::c_void>().cast_mut(),
-                    buf.as_ptr().cast::<libc::c_void>().cast_mut(),
-                    num_times * size_of::<libc::timespec>(),
+                    ta.attrlist(),
+                    ta.times_buf(),
+                    ta.times_buf_size(),
                     0
                 ) })?;
                 Ok(())
             }
             target_os = "android" => {
-                let times = [to_timespec(times.accessed)?, to_timespec(times.modified)?];
+                let times = [file_time_to_timespec(times.accessed)?, file_time_to_timespec(times.modified)?];
                 // futimens requires Android API level 19
                 cvt(unsafe {
                     weak!(
@@ -1697,7 +1661,7 @@ impl File {
                         return Ok(());
                     }
                 }
-                let times = [to_timespec(times.accessed)?, to_timespec(times.modified)?];
+                let times = [file_time_to_timespec(times.accessed)?, file_time_to_timespec(times.modified)?];
                 cvt(unsafe { libc::futimens(self.as_raw_fd(), times.as_ptr()) })?;
                 Ok(())
             }
@@ -1705,6 +1669,74 @@ impl File {
     }
 }
 
+#[cfg(not(any(
+    target_os = "redox",
+    target_os = "espidf",
+    target_os = "horizon",
+    target_os = "nuttx",
+)))]
+fn file_time_to_timespec(time: Option<SystemTime>) -> io::Result<libc::timespec> {
+    match time {
+        Some(time) if let Some(ts) = time.t.to_timespec() => Ok(ts),
+        Some(time) if time > crate::sys::time::UNIX_EPOCH => Err(io::const_error!(
+            io::ErrorKind::InvalidInput,
+            "timestamp is too large to set as a file time",
+        )),
+        Some(_) => Err(io::const_error!(
+            io::ErrorKind::InvalidInput,
+            "timestamp is too small to set as a file time",
+        )),
+        None => Ok(libc::timespec { tv_sec: 0, tv_nsec: libc::UTIME_OMIT as _ }),
+    }
+}
+
+#[cfg(target_vendor = "apple")]
+struct TimesAttrlist {
+    buf: [mem::MaybeUninit<libc::timespec>; 3],
+    attrlist: libc::attrlist,
+    num_times: usize,
+}
+
+#[cfg(target_vendor = "apple")]
+impl TimesAttrlist {
+    fn from_times(times: &FileTimes) -> io::Result<Self> {
+        let mut this = Self {
+            buf: [mem::MaybeUninit::<libc::timespec>::uninit(); 3],
+            attrlist: unsafe { mem::zeroed() },
+            num_times: 0,
+        };
+        this.attrlist.bitmapcount = libc::ATTR_BIT_MAP_COUNT;
+        if times.created.is_some() {
+            this.buf[this.num_times].write(file_time_to_timespec(times.created)?);
+            this.num_times += 1;
+            this.attrlist.commonattr |= libc::ATTR_CMN_CRTIME;
+        }
+        if times.modified.is_some() {
+            this.buf[this.num_times].write(file_time_to_timespec(times.modified)?);
+            this.num_times += 1;
+            this.attrlist.commonattr |= libc::ATTR_CMN_MODTIME;
+        }
+        if times.accessed.is_some() {
+            this.buf[this.num_times].write(file_time_to_timespec(times.accessed)?);
+            this.num_times += 1;
+            this.attrlist.commonattr |= libc::ATTR_CMN_ACCTIME;
+        }
+        Ok(this)
+    }
+
+    fn attrlist(&self) -> *mut libc::c_void {
+        (&raw const self.attrlist).cast::<libc::c_void>().cast_mut()
+    }
+
+    fn times_buf(&self) -> *mut libc::c_void {
+        self.buf.as_ptr().cast::<libc::c_void>().cast_mut()
+    }
+
+    fn times_buf_size(&self) -> usize {
+        self.num_times * size_of::<libc::timespec>()
+    }
+}
+
 impl DirBuilder {
     pub fn new() -> DirBuilder {
         DirBuilder { mode: 0o777 }
@@ -2081,6 +2113,87 @@ fn open_from(from: &Path) -> io::Result<(crate::fs::File, crate::fs::Metadata)>
     Ok((reader, metadata))
 }
 
+fn set_times_impl(p: &CStr, times: FileTimes, flags: c_int) -> io::Result<()> {
+    cfg_select! {
+       any(target_os = "redox", target_os = "espidf", target_os = "horizon", target_os = "nuttx") => {
+            let _ = (p, times, flags);
+            Err(io::const_error!(
+                io::ErrorKind::Unsupported,
+                "setting file times not supported",
+            ))
+       }
+       target_vendor = "apple" => {
+            // Apple platforms use setattrlist which supports setting times on symlinks
+            //let (attrlist, buf, num_times) = set_attrlist_with_times(&times)?;
+            let ta = TimesAttrlist::from_times(&times)?;
+            let options = if flags == libc::AT_SYMLINK_NOFOLLOW {
+                libc::FSOPT_NOFOLLOW
+            } else {
+                0
+            };
+
+            cvt(unsafe { libc::setattrlist(
+                p.as_ptr(),
+                ta.attrlist(),
+                ta.times_buf(),
+                ta.times_buf_size(),
+                options as u32
+            ) })?;
+            Ok(())
+       }
+       target_os = "android" => {
+            let times = [file_time_to_timespec(times.accessed)?, file_time_to_timespec(times.modified)?];
+            // utimensat requires Android API level 19
+            cvt(unsafe {
+                weak!(
+                    fn utimensat(dirfd: c_int, path: *const libc::c_char, times: *const libc::timespec, flags: c_int) -> c_int;
+                );
+                match utimensat.get() {
+                    Some(utimensat) => utimensat(libc::AT_FDCWD, p.as_ptr(), times.as_ptr(), flags),
+                    None => return Err(io::const_error!(
+                        io::ErrorKind::Unsupported,
+                        "setting file times requires Android API level >= 19",
+                    )),
+                }
+            })?;
+            Ok(())
+       }
+       _ => {
+            #[cfg(all(target_os = "linux", target_env = "gnu", target_pointer_width = "32", not(target_arch = "riscv32")))]
+            {
+                use crate::sys::{time::__timespec64, weak::weak};
+
+                // Added in glibc 2.34
+                weak!(
+                    fn __utimensat64(dirfd: c_int, path: *const c_char, times: *const __timespec64, flags: c_int) -> c_int;
+                );
+
+                if let Some(utimensat64) = __utimensat64.get() {
+                    let to_timespec = |time: Option<SystemTime>| time.map(|time| time.t.to_timespec64())
+                        .unwrap_or(__timespec64::new(0, libc::UTIME_OMIT as _));
+                    let times = [to_timespec(times.accessed), to_timespec(times.modified)];
+                    cvt(unsafe { utimensat64(libc::AT_FDCWD, p.as_ptr(), times.as_ptr(), flags) })?;
+                    return Ok(());
+                }
+            }
+            let times = [file_time_to_timespec(times.accessed)?, file_time_to_timespec(times.modified)?];
+            cvt(unsafe { libc::utimensat(libc::AT_FDCWD, p.as_ptr(), times.as_ptr(), flags) })?;
+            Ok(())
+         }
+    }
+}
+
+#[inline(always)]
+pub fn set_times(p: &CStr, times: FileTimes) -> io::Result<()> {
+    // flags = 0 means follow symlinks
+    set_times_impl(p, times, 0)
+}
+
+#[inline(always)]
+pub fn set_times_nofollow(p: &CStr, times: FileTimes) -> io::Result<()> {
+    set_times_impl(p, times, libc::AT_SYMLINK_NOFOLLOW)
+}
+
 #[cfg(target_os = "espidf")]
 fn open_to_and_set_permissions(
     to: &Path,
diff --git a/library/std/src/sys/fs/unsupported.rs b/library/std/src/sys/fs/unsupported.rs
index efaddb51b3751..f222151d18e25 100644
--- a/library/std/src/sys/fs/unsupported.rs
+++ b/library/std/src/sys/fs/unsupported.rs
@@ -312,6 +312,14 @@ pub fn set_perm(_p: &Path, perm: FilePermissions) -> io::Result<()> {
     match perm.0 {}
 }
 
+pub fn set_times(_p: &Path, _times: FileTimes) -> io::Result<()> {
+    unsupported()
+}
+
+pub fn set_times_nofollow(_p: &Path, _times: FileTimes) -> io::Result<()> {
+    unsupported()
+}
+
 pub fn rmdir(_p: &Path) -> io::Result<()> {
     unsupported()
 }
diff --git a/library/std/src/sys/fs/vexos.rs b/library/std/src/sys/fs/vexos.rs
index f642e7cb074ec..99b156d535768 100644
--- a/library/std/src/sys/fs/vexos.rs
+++ b/library/std/src/sys/fs/vexos.rs
@@ -492,6 +492,14 @@ pub fn set_perm(_p: &Path, _perm: FilePermissions) -> io::Result<()> {
     unsupported()
 }
 
+pub fn set_times(_p: &Path, _times: FileTimes) -> io::Result<()> {
+    unsupported()
+}
+
+pub fn set_times_nofollow(_p: &Path, _times: FileTimes) -> io::Result<()> {
+    unsupported()
+}
+
 pub fn exists(path: &Path) -> io::Result<bool> {
     run_path_with_cstr(path, &|path| Ok(unsafe { vex_sdk::vexFileStatus(path.as_ptr()) } != 0))
 }
diff --git a/library/std/src/sys/fs/wasi.rs b/library/std/src/sys/fs/wasi.rs
index 0b65b9cb389df..92eb35317415f 100644
--- a/library/std/src/sys/fs/wasi.rs
+++ b/library/std/src/sys/fs/wasi.rs
@@ -536,17 +536,9 @@ impl File {
     }
 
     pub fn set_times(&self, times: FileTimes) -> io::Result<()> {
-        let to_timestamp = |time: Option<SystemTime>| match time {
-            Some(time) if let Some(ts) = time.to_wasi_timestamp() => Ok(ts),
-            Some(_) => Err(io::const_error!(
-                io::ErrorKind::InvalidInput,
-                "timestamp is too large to set as a file time",
-            )),
-            None => Ok(0),
-        };
         self.fd.filestat_set_times(
-            to_timestamp(times.accessed)?,
-            to_timestamp(times.modified)?,
+            to_wasi_timestamp_or_now(times.accessed)?,
+            to_wasi_timestamp_or_now(times.modified)?,
             times.accessed.map_or(0, |_| wasi::FSTFLAGS_ATIM)
                 | times.modified.map_or(0, |_| wasi::FSTFLAGS_MTIM),
         )
@@ -643,6 +635,45 @@ pub fn set_perm(_p: &Path, _perm: FilePermissions) -> io::Result<()> {
     unsupported()
 }
 
+#[inline(always)]
+pub fn set_times(p: &Path, times: FileTimes) -> io::Result<()> {
+    let (dir, file) = open_parent(p)?;
+    set_times_impl(&dir, &file, times, wasi::LOOKUPFLAGS_SYMLINK_FOLLOW)
+}
+
+#[inline(always)]
+pub fn set_times_nofollow(p: &Path, times: FileTimes) -> io::Result<()> {
+    let (dir, file) = open_parent(p)?;
+    set_times_impl(&dir, &file, times, 0)
+}
+
+fn to_wasi_timestamp_or_now(time: Option<SystemTime>) -> io::Result<wasi::Timestamp> {
+    match time {
+        Some(time) if let Some(ts) = time.to_wasi_timestamp() => Ok(ts),
+        Some(_) => Err(io::const_error!(
+            io::ErrorKind::InvalidInput,
+            "timestamp is too large to set as a file time",
+        )),
+        None => Ok(0),
+    }
+}
+
+fn set_times_impl(
+    fd: &WasiFd,
+    path: &Path,
+    times: FileTimes,
+    flags: wasi::Lookupflags,
+) -> io::Result<()> {
+    fd.path_filestat_set_times(
+        flags,
+        osstr2str(path.as_ref())?,
+        to_wasi_timestamp_or_now(times.accessed)?,
+        to_wasi_timestamp_or_now(times.modified)?,
+        times.accessed.map_or(0, |_| wasi::FSTFLAGS_ATIM)
+            | times.modified.map_or(0, |_| wasi::FSTFLAGS_MTIM),
+    )
+}
+
 pub fn rmdir(p: &Path) -> io::Result<()> {
     let (dir, file) = open_parent(p)?;
     dir.remove_directory(osstr2str(file.as_ref())?)
diff --git a/library/std/src/sys/fs/windows.rs b/library/std/src/sys/fs/windows.rs
index ccfe410627f70..f2d325da35c7d 100644
--- a/library/std/src/sys/fs/windows.rs
+++ b/library/std/src/sys/fs/windows.rs
@@ -1514,6 +1514,23 @@ pub fn set_perm(p: &WCStr, perm: FilePermissions) -> io::Result<()> {
     }
 }
 
+pub fn set_times(p: &WCStr, times: FileTimes) -> io::Result<()> {
+    let mut opts = OpenOptions::new();
+    opts.write(true);
+    opts.custom_flags(c::FILE_FLAG_BACKUP_SEMANTICS);
+    let file = File::open_native(p, &opts)?;
+    file.set_times(times)
+}
+
+pub fn set_times_nofollow(p: &WCStr, times: FileTimes) -> io::Result<()> {
+    let mut opts = OpenOptions::new();
+    opts.write(true);
+    // `FILE_FLAG_OPEN_REPARSE_POINT` for no_follow behavior
+    opts.custom_flags(c::FILE_FLAG_BACKUP_SEMANTICS | c::FILE_FLAG_OPEN_REPARSE_POINT);
+    let file = File::open_native(p, &opts)?;
+    file.set_times(times)
+}
+
 fn get_path(f: &File) -> io::Result<PathBuf> {
     fill_utf16_buf(
         |buf, sz| unsafe {
diff --git a/library/std/src/sys/pal/vexos/mod.rs b/library/std/src/sys/pal/vexos/mod.rs
index 61a34b0f68a30..3a37c8f2d4885 100644
--- a/library/std/src/sys/pal/vexos/mod.rs
+++ b/library/std/src/sys/pal/vexos/mod.rs
@@ -1,4 +1,3 @@
-#[path = "../unsupported/os.rs"]
 pub mod os;
 #[path = "../unsupported/pipe.rs"]
 pub mod pipe;
diff --git a/library/std/src/sys/pal/vexos/os.rs b/library/std/src/sys/pal/vexos/os.rs
new file mode 100644
index 0000000000000..405f7c918f4a5
--- /dev/null
+++ b/library/std/src/sys/pal/vexos/os.rs
@@ -0,0 +1,19 @@
+#[expect(dead_code)]
+#[path = "../unsupported/os.rs"]
+mod unsupported_os;
+pub use unsupported_os::{
+    JoinPathsError, SplitPaths, chdir, current_exe, errno, error_string, getcwd, getpid, home_dir,
+    join_paths, split_paths, temp_dir,
+};
+
+pub use super::unsupported;
+
+pub fn exit(_code: i32) -> ! {
+    unsafe {
+        vex_sdk::vexSystemExitRequest();
+
+        loop {
+            vex_sdk::vexTasksRun();
+        }
+    }
+}
diff --git a/tests/ui/traits/next-solver/cycles/forced_ambiguity-use-head-maybe-cause.rs b/tests/ui/traits/next-solver/cycles/forced_ambiguity-use-head-maybe-cause.rs
new file mode 100644
index 0000000000000..aa5893d621cdb
--- /dev/null
+++ b/tests/ui/traits/next-solver/cycles/forced_ambiguity-use-head-maybe-cause.rs
@@ -0,0 +1,44 @@
+//@ compile-flags: -Znext-solver
+#![feature(rustc_attrs)]
+#![rustc_no_implicit_bounds]
+
+// A regression test making sure that when forcing dependent
+// provisional cache entries to ambiguous, we use the `MaybeCause`
+// of the cycle head. We ended up trying to use the current result
+// of the provisional cache entry, which is incorrect and caused an
+// ICE when trying to unwrap it.
+
+struct Root<T>(T);
+struct Head<T>(T);
+struct Error<T>(T);
+struct NotImplemented<T>(T);
+
+#[rustc_coinductive]
+trait Trait {}
+impl<T> Trait for Root<T>
+where
+    Head<T>: Trait,
+{}
+
+impl<T> Trait for Head<T>
+where
+    Root<T>: Trait,
+    T: Trait, // ambiguous
+{}
+
+impl<T> Trait for Head<T>
+where
+    Error<T>: Trait,
+    NotImplemented<T>: Trait,
+{}
+
+impl<T> Trait for Error<T>
+where
+    Head<T>: Trait,
+    NotImplemented<T>: Trait,
+{}
+
+fn impls_trait<T: Trait>() {}
+fn main() {
+    impls_trait::<Root<_>>() //~ ERROR type annotations needed
+}
diff --git a/tests/ui/traits/next-solver/cycles/forced_ambiguity-use-head-maybe-cause.stderr b/tests/ui/traits/next-solver/cycles/forced_ambiguity-use-head-maybe-cause.stderr
new file mode 100644
index 0000000000000..dd4049a66d0b4
--- /dev/null
+++ b/tests/ui/traits/next-solver/cycles/forced_ambiguity-use-head-maybe-cause.stderr
@@ -0,0 +1,27 @@
+error[E0283]: type annotations needed
+  --> $DIR/forced_ambiguity-use-head-maybe-cause.rs:43:19
+   |
+LL |     impls_trait::<Root<_>>()
+   |                   ^^^^^^^ cannot infer type for struct `Head<_>`
+   |
+   = note: cannot satisfy `Head<_>: Trait`
+   = help: the trait `Trait` is implemented for `Head<T>`
+note: required for `Root<_>` to implement `Trait`
+  --> $DIR/forced_ambiguity-use-head-maybe-cause.rs:18:9
+   |
+LL | impl<T> Trait for Root<T>
+   |         ^^^^^     ^^^^^^^
+LL | where
+LL |     Head<T>: Trait,
+   |              ----- unsatisfied trait bound introduced here
+   = note: 8 redundant requirements hidden
+   = note: required for `Root<_>` to implement `Trait`
+note: required by a bound in `impls_trait`
+  --> $DIR/forced_ambiguity-use-head-maybe-cause.rs:41:19
+   |
+LL | fn impls_trait<T: Trait>() {}
+   |                   ^^^^^ required by this bound in `impls_trait`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0283`.