Name the lifetime in the signature of SettableValue.set_on()

This change names the lifetime of Mut<'a, T> and requires that T outlives 'a. The motivation for this change came up while implementing `Map<K, ProtoStr>`. The Map implementation makes it so that `V` needs to implement the `MapWithKeyOps` trait which has an associated type with a lifetime (`Value<'a>`. The lifetime bound on `T` ensures that e.g. for `MapWithKeyOps<Value<'b>=&'b ProtoStr>` `'a` outlives `'b`.

PiperOrigin-RevId: 585657154

rust/macros.rs

@@ -19,11 +19,11 @@
 /// ```
 macro_rules! impl_forwarding_settable_value {
     ($proxied:ty, $self:ident => $self_forwarding_expr:expr) => {
-        fn set_on(
+        fn set_on<'b>(
             $self,
             _private: $crate::__internal::Private,
-            mutator: $crate::Mut<'_, $proxied>,
-        ) {
+            mutator: $crate::Mut<'b, $proxied>,
+        ) where $proxied: 'b {
             ($self_forwarding_expr).set_on(Private, mutator)
         }
 

rust/map.rs

@@ -78,7 +78,9 @@ macro_rules! impl_scalar_map_keys {
         }
 
         impl<'a, V: [< MapWith $t:camel KeyOps >]> SettableValue<Map<$t, V>> for MapView<'a, $t, V> {
-          fn set_on(self, _private: Private, mut mutator: Mut<'_, Map<$t, V>>) {
+          fn set_on<'b>(self, _private: Private, mut mutator: Mut<'b, Map<$t, V>>)
+          where
+            Map<$t, V>: 'b {
             mutator.copy_from(self);
           }
         }

rust/optional.rs

@@ -589,7 +589,10 @@ mod tests {
     }
 
     impl SettableValue<VtableProxied> for View<'_, VtableProxied> {
-        fn set_on(self, _private: Private, mutator: Mut<VtableProxied>) {
+        fn set_on<'a>(self, _private: Private, mutator: Mut<'a, VtableProxied>)
+        where
+            VtableProxied: 'a,
+        {
             SettableValue::<VtableProxied>::set_on(self.val(), Private, mutator)
         }
 
@@ -603,7 +606,10 @@ mod tests {
     }
 
     impl SettableValue<VtableProxied> for i32 {
-        fn set_on(self, _private: Private, mutator: Mut<VtableProxied>) {
+        fn set_on<'a>(self, _private: Private, mutator: Mut<'a, VtableProxied>)
+        where
+            VtableProxied: 'a,
+        {
             (mutator.vtable.set)(mutator.msg, self)
         }
 

rust/primitive.rs

@@ -116,7 +116,7 @@ macro_rules! impl_singular_primitives {
           }
 
           impl SettableValue<$t> for $t {
-              fn set_on(self, _private: Private, mutator: Mut<'_, $t>) {
+              fn set_on<'a>(self, _private: Private, mutator: Mut<'a, $t>) where $t: 'a {
                 match mutator {
                   PrimitiveMut::Singular(s) => {
                       unsafe { (s.inner).set(self) };

rust/proxied.rs

@@ -239,7 +239,9 @@ where
 {
     /// Consumes `self` to set the given mutator to its value.
     #[doc(hidden)]
-    fn set_on(self, _private: Private, mutator: Mut<'_, T>);
+    fn set_on<'a>(self, _private: Private, mutator: Mut<'a, T>)
+    where
+        T: 'a;
 
     /// Consumes `self` and `absent_mutator` to set the given empty field to
     /// a value.
@@ -352,25 +354,37 @@ mod tests {
     }
 
     impl SettableValue<MyProxied> for MyProxiedView<'_> {
-        fn set_on(self, _private: Private, mutator: Mut<MyProxied>) {
+        fn set_on<'a>(self, _private: Private, mutator: Mut<'a, MyProxied>)
+        where
+            MyProxied: 'a,
+        {
             mutator.my_proxied_ref.val = self.my_proxied_ref.val.clone();
         }
     }
 
     impl SettableValue<MyProxied> for String {
-        fn set_on(self, _private: Private, mutator: Mut<MyProxied>) {
+        fn set_on<'a>(self, _private: Private, mutator: Mut<'a, MyProxied>)
+        where
+            MyProxied: 'a,
+        {
             mutator.my_proxied_ref.val = self;
         }
     }
 
     impl SettableValue<MyProxied> for &'_ str {
-        fn set_on(self, _private: Private, mutator: Mut<MyProxied>) {
+        fn set_on<'a>(self, _private: Private, mutator: Mut<'a, MyProxied>)
+        where
+            MyProxied: 'a,
+        {
             mutator.my_proxied_ref.val.replace_range(.., self);
         }
     }
 
     impl SettableValue<MyProxied> for Cow<'_, str> {
-        fn set_on(self, _private: Private, mutator: Mut<MyProxied>) {
+        fn set_on<'a>(self, _private: Private, mutator: Mut<'a, MyProxied>)
+        where
+            MyProxied: 'a,
+        {
             match self {
                 Cow::Owned(x) => <String as SettableValue<MyProxied>>::set_on(x, Private, mutator),
                 Cow::Borrowed(x) => <&str as SettableValue<MyProxied>>::set_on(x, Private, mutator),

rust/repeated.rs

@@ -138,7 +138,9 @@ macro_rules! impl_repeated_primitives {
             }
 
             impl <'a> SettableValue<Repeated<$t>> for RepeatedView<'a, $t> {
-                fn set_on(self, _private: Private, mut mutator: Mut<'_, Repeated<$t>>) {
+                fn set_on<'b> (self, _private: Private, mut mutator: Mut<'b, Repeated<$t>>)
+                where
+                    Repeated<$t>: 'b {
                     mutator.copy_from(self);
                 }
             }

rust/string.rs

@@ -185,7 +185,10 @@ impl<'msg> MutProxy<'msg> for BytesMut<'msg> {
 }
 
 impl SettableValue<[u8]> for &'_ [u8] {
-    fn set_on(self, _private: Private, mutator: BytesMut<'_>) {
+    fn set_on<'a>(self, _private: Private, mutator: Mut<'a, [u8]>)
+    where
+        [u8]: 'a,
+    {
         // SAFETY: this is a `bytes` field with no restriction on UTF-8.
         unsafe { mutator.inner.set(self) }
     }
@@ -695,7 +698,10 @@ impl<'msg> MutProxy<'msg> for ProtoStrMut<'msg> {
 }
 
 impl SettableValue<ProtoStr> for &'_ ProtoStr {
-    fn set_on(self, _private: Private, mutator: ProtoStrMut<'_>) {
+    fn set_on<'b>(self, _private: Private, mutator: Mut<'b, ProtoStr>)
+    where
+        ProtoStr: 'b,
+    {
         // SAFETY: A `ProtoStr` has the same UTF-8 validity requirement as the runtime.
         unsafe { mutator.bytes.inner.set(self.as_bytes()) }
     }

src/google/protobuf/compiler/rust/message.cc

@@ -367,7 +367,9 @@ void GenerateRs(Context<Descriptor> msg) {
         }
 
         impl<'a> $pb$::SettableValue<$Msg$> for $Msg$View<'a> {
-          fn set_on(self, _private: $pb$::__internal::Private, _mutator: $pb$::Mut<$Msg$>) {
+          fn set_on<'b>(self, _private: $pb$::__internal::Private, _mutator: $pb$::Mut<'b, $Msg$>)
+          where
+            $Msg$: 'b {
             todo!()
           }
         }