diff --git a/core/engine/src/builtins/temporal/instant/mod.rs b/core/engine/src/builtins/temporal/instant/mod.rs
index 2b7173b4018..161ca0ce03b 100644
--- a/core/engine/src/builtins/temporal/instant/mod.rs
+++ b/core/engine/src/builtins/temporal/instant/mod.rs
@@ -153,7 +153,6 @@ impl Instant {
             None,
             context,
         )
-        .map(Into::into)
     }
 
     pub(crate) fn from_epoch_milliseconds(
@@ -172,7 +171,6 @@ impl Instant {
             None,
             context,
         )
-        .map(Into::into)
     }
 
     pub(crate) fn from_epoch_nanoseconds(
@@ -190,7 +188,6 @@ impl Instant {
             None,
             context,
         )
-        .map(Into::into)
     }
 
     pub(crate) fn compare(
diff --git a/core/engine/src/builtins/temporal/now.rs b/core/engine/src/builtins/temporal/now.rs
index 9fbc1bf851f..5e9aaba373e 100644
--- a/core/engine/src/builtins/temporal/now.rs
+++ b/core/engine/src/builtins/temporal/now.rs
@@ -70,7 +70,7 @@ impl Now {
     /// 2.2.2 `Temporal.Now.instant()`
     fn instant(_: &JsValue, _: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
         let epoch_nanos = system_nanoseconds(context)?;
-        create_temporal_instant(Instant::from(epoch_nanos), None, context).map(Into::into)
+        create_temporal_instant(Instant::from(epoch_nanos), None, context)
     }
 
     /// 2.2.3 `Temporal.Now.plainDateTimeISO ( [ temporalTimeZoneLike ] )`
diff --git a/core/engine/src/builtins/temporal/plain_date_time/mod.rs b/core/engine/src/builtins/temporal/plain_date_time/mod.rs
index c254e4699c8..e893ee32fd5 100644
--- a/core/engine/src/builtins/temporal/plain_date_time/mod.rs
+++ b/core/engine/src/builtins/temporal/plain_date_time/mod.rs
@@ -1218,8 +1218,7 @@ fn to_partial_datetime(
             let finite = v.to_finitef64(context)?;
             Ok::<u8, JsError>(finite.as_integer_with_truncation::<u8>())
         })
-        .transpose()?
-        .map(Into::into);
+        .transpose()?;
     // TODO: `temporal_rs` needs a `has_era` method
     let (era, era_year) = if calendar == Calendar::default() {
         (None, None)
@@ -1254,8 +1253,7 @@ fn to_partial_datetime(
             let finite = v.to_finitef64(context)?;
             Ok::<u16, JsError>(finite.as_integer_with_truncation::<u16>())
         })
-        .transpose()?
-        .map(Into::into);
+        .transpose()?;
 
     let millisecond = partial_object
         .get(js_string!("millisecond"), context)?
@@ -1263,8 +1261,7 @@ fn to_partial_datetime(
             let finite = v.to_finitef64(context)?;
             Ok::<u16, JsError>(finite.as_integer_with_truncation::<u16>())
         })
-        .transpose()?
-        .map(Into::into);
+        .transpose()?;
 
     let minute = partial_object
         .get(js_string!("minute"), context)?
@@ -1272,8 +1269,7 @@ fn to_partial_datetime(
             let finite = v.to_finitef64(context)?;
             Ok::<u8, JsError>(finite.as_integer_with_truncation::<u8>())
         })
-        .transpose()?
-        .map(Into::into);
+        .transpose()?;
 
     let month = partial_object
         .get(js_string!("month"), context)?
@@ -1305,8 +1301,7 @@ fn to_partial_datetime(
             let finite = v.to_finitef64(context)?;
             Ok::<u16, JsError>(finite.as_integer_with_truncation::<u16>())
         })
-        .transpose()?
-        .map(Into::into);
+        .transpose()?;
 
     let second = partial_object
         .get(js_string!("second"), context)?
@@ -1314,8 +1309,7 @@ fn to_partial_datetime(
             let finite = v.to_finitef64(context)?;
             Ok::<u8, JsError>(finite.as_integer_with_truncation::<u8>())
         })
-        .transpose()?
-        .map(Into::into);
+        .transpose()?;
 
     let year = partial_object
         .get(js_string!("year"), context)?
diff --git a/core/engine/src/builtins/temporal/plain_time/mod.rs b/core/engine/src/builtins/temporal/plain_time/mod.rs
index 6af1e9bbf45..cec8efd8787 100644
--- a/core/engine/src/builtins/temporal/plain_time/mod.rs
+++ b/core/engine/src/builtins/temporal/plain_time/mod.rs
@@ -722,8 +722,7 @@ pub(crate) fn to_partial_time_record(
             let finite = v.to_finitef64(context)?;
             Ok::<u8, JsError>(finite.as_integer_with_truncation::<u8>())
         })
-        .transpose()?
-        .map(Into::into);
+        .transpose()?;
 
     let microsecond = partial_object
         .get(js_string!("microsecond"), context)?
@@ -731,8 +730,7 @@ pub(crate) fn to_partial_time_record(
             let finite = v.to_finitef64(context)?;
             Ok::<u16, JsError>(finite.as_integer_with_truncation::<u16>())
         })
-        .transpose()?
-        .map(Into::into);
+        .transpose()?;
 
     let millisecond = partial_object
         .get(js_string!("millisecond"), context)?
@@ -740,8 +738,7 @@ pub(crate) fn to_partial_time_record(
             let finite = v.to_finitef64(context)?;
             Ok::<u16, JsError>(finite.as_integer_with_truncation::<u16>())
         })
-        .transpose()?
-        .map(Into::into);
+        .transpose()?;
 
     let minute = partial_object
         .get(js_string!("minute"), context)?
@@ -749,8 +746,7 @@ pub(crate) fn to_partial_time_record(
             let finite = v.to_finitef64(context)?;
             Ok::<u8, JsError>(finite.as_integer_with_truncation::<u8>())
         })
-        .transpose()?
-        .map(Into::into);
+        .transpose()?;
 
     let nanosecond = partial_object
         .get(js_string!("nanosecond"), context)?
@@ -758,8 +754,7 @@ pub(crate) fn to_partial_time_record(
             let finite = v.to_finitef64(context)?;
             Ok::<u16, JsError>(finite.as_integer_with_truncation::<u16>())
         })
-        .transpose()?
-        .map(Into::into);
+        .transpose()?;
 
     let second = partial_object
         .get(js_string!("second"), context)?
@@ -767,8 +762,7 @@ pub(crate) fn to_partial_time_record(
             let finite = v.to_finitef64(context)?;
             Ok::<u8, JsError>(finite.as_integer_with_truncation::<u8>())
         })
-        .transpose()?
-        .map(Into::into);
+        .transpose()?;
 
     Ok(PartialTime {
         hour,
diff --git a/core/engine/src/builtins/temporal/plain_year_month/mod.rs b/core/engine/src/builtins/temporal/plain_year_month/mod.rs
index a44ded219e2..a530f214efe 100644
--- a/core/engine/src/builtins/temporal/plain_year_month/mod.rs
+++ b/core/engine/src/builtins/temporal/plain_year_month/mod.rs
@@ -214,13 +214,8 @@ impl BuiltInConstructor for PlainYearMonth {
             .transpose()?;
 
         // 7. Return ? CreateTemporalYearMonth(y, m, calendar, ref, NewTarget).
-        let inner = InnerYearMonth::new_with_overflow(
-            y,
-            m,
-            ref_day.map(Into::into),
-            calendar,
-            ArithmeticOverflow::Reject,
-        )?;
+        let inner =
+            InnerYearMonth::new_with_overflow(y, m, ref_day, calendar, ArithmeticOverflow::Reject)?;
 
         create_temporal_year_month(inner, Some(new_target), context)
     }
diff --git a/core/engine/src/builtins/temporal/zoneddatetime/mod.rs b/core/engine/src/builtins/temporal/zoneddatetime/mod.rs
index a52e020f199..81ccdac735a 100644
--- a/core/engine/src/builtins/temporal/zoneddatetime/mod.rs
+++ b/core/engine/src/builtins/temporal/zoneddatetime/mod.rs
@@ -1133,7 +1133,7 @@ impl ZonedDateTime {
                 JsNativeError::typ().with_message("the this object must be a ZonedDateTime object.")
             })?;
 
-        create_temporal_instant(zdt.inner.to_instant(), None, context).map(Into::into)
+        create_temporal_instant(zdt.inner.to_instant(), None, context)
     }
 
     /// 6.3.48 `Temporal.ZonedDateTime.prototype.toPlainDate ( )`
diff --git a/core/engine/src/error.rs b/core/engine/src/error.rs
index c3f64d783e2..f8f7337af1d 100644
--- a/core/engine/src/error.rs
+++ b/core/engine/src/error.rs
@@ -619,7 +619,7 @@ impl JsError {
     /// Is the [`JsError`] catchable in JavaScript.
     #[inline]
     pub(crate) fn is_catchable(&self) -> bool {
-        self.as_native().map_or(true, JsNativeError::is_catchable)
+        self.as_native().is_none_or(JsNativeError::is_catchable)
     }
 }
 
diff --git a/core/engine/src/module/namespace.rs b/core/engine/src/module/namespace.rs
index 196e0dd0842..b0629b41eaa 100644
--- a/core/engine/src/module/namespace.rs
+++ b/core/engine/src/module/namespace.rs
@@ -213,7 +213,7 @@ fn module_namespace_exotic_define_own_property(
 
     // 8. If Desc has a [[Value]] field, return SameValue(Desc.[[Value]], current.[[Value]]).
     // 9. Return true.
-    Ok(desc.value().map_or(true, |v| v == current.expect_value()))
+    Ok(desc.value().is_none_or(|v| v == current.expect_value()))
 }
 
 /// [`[[HasProperty]] ( P )`][spec]
diff --git a/core/engine/src/object/jsobject.rs b/core/engine/src/object/jsobject.rs
index db02acd3c37..a660dbe12be 100644
--- a/core/engine/src/object/jsobject.rs
+++ b/core/engine/src/object/jsobject.rs
@@ -1,6 +1,10 @@
 //! This module implements the `JsObject` structure.
 //!
 //! The `JsObject` is a garbage collected Object.
+#![allow(
+    unknown_lints,
+    reason = "unpredictable_function_pointer_comparisons doesn't exist on 1.84"
+)]
 
 use super::{
     internal_methods::{InternalMethodContext, InternalObjectMethods, ORDINARY_INTERNAL_METHODS},
@@ -408,7 +412,7 @@ impl JsObject {
         let get = if let Some(getter) = self.try_get(js_string!("get"), context)? {
             // b. If IsCallable(getter) is false and getter is not undefined, throw a TypeError exception.
             // todo: extract IsCallable to be callable from Value
-            if !getter.is_undefined() && getter.as_object().map_or(true, |o| !o.is_callable()) {
+            if !getter.is_undefined() && getter.as_object().is_none_or(|o| !o.is_callable()) {
                 return Err(JsNativeError::typ()
                     .with_message("Property descriptor getter must be callable")
                     .into());
@@ -425,7 +429,7 @@ impl JsObject {
         let set = if let Some(setter) = self.try_get(js_string!("set"), context)? {
             // 14.b. If IsCallable(setter) is false and setter is not undefined, throw a TypeError exception.
             // todo: extract IsCallable to be callable from Value
-            if !setter.is_undefined() && setter.as_object().map_or(true, |o| !o.is_callable()) {
+            if !setter.is_undefined() && setter.as_object().is_none_or(|o| !o.is_callable()) {
                 return Err(JsNativeError::typ()
                     .with_message("Property descriptor setter must be callable")
                     .into());
@@ -748,6 +752,10 @@ impl<T: NativeObject + ?Sized> JsObject<T> {
     /// [spec]: https://tc39.es/ecma262/#sec-iscallable
     #[inline]
     #[must_use]
+    #[expect(
+        unpredictable_function_pointer_comparisons,
+        reason = "can only use `ptr::fn_addr_eq` on rustc 1.85"
+    )]
     pub fn is_callable(&self) -> bool {
         self.inner.vtable.__call__ != ORDINARY_INTERNAL_METHODS.__call__
     }
@@ -760,6 +768,10 @@ impl<T: NativeObject + ?Sized> JsObject<T> {
     /// [spec]: https://tc39.es/ecma262/#sec-isconstructor
     #[inline]
     #[must_use]
+    #[expect(
+        unpredictable_function_pointer_comparisons,
+        reason = "can only use `ptr::fn_addr_eq` on rustc 1.85"
+    )]
     pub fn is_constructor(&self) -> bool {
         self.inner.vtable.__construct__ != ORDINARY_INTERNAL_METHODS.__construct__
     }
diff --git a/core/engine/src/vm/opcode/concat/mod.rs b/core/engine/src/vm/opcode/concat/mod.rs
index 09b39862817..349bec1752a 100644
--- a/core/engine/src/vm/opcode/concat/mod.rs
+++ b/core/engine/src/vm/opcode/concat/mod.rs
@@ -22,13 +22,7 @@ impl ConcatToString {
             let val = registers.get(*value);
             strings.push(val.to_string(context)?);
         }
-        let s = JsString::concat_array(
-            &strings
-                .iter()
-                .map(JsString::as_str)
-                .map(Into::into)
-                .collect::<Vec<_>>(),
-        );
+        let s = JsString::concat_array(&strings.iter().map(JsString::as_str).collect::<Vec<_>>());
         registers.set(string, s.into());
         Ok(CompletionType::Normal)
     }
diff --git a/core/parser/src/parser/expression/primary/object_initializer/mod.rs b/core/parser/src/parser/expression/primary/object_initializer/mod.rs
index 7215767bd29..4f0d5869e3c 100644
--- a/core/parser/src/parser/expression/primary/object_initializer/mod.rs
+++ b/core/parser/src/parser/expression/primary/object_initializer/mod.rs
@@ -125,9 +125,9 @@ where
 
         if let Some(position) = duplicate_proto_position {
             if !cursor.json_parse()
-                && cursor.peek(0, interner)?.map_or(true, |token| {
-                    token.kind() != &TokenKind::Punctuator(Punctuator::Assign)
-                })
+                && cursor
+                    .peek(0, interner)?
+                    .is_none_or(|token| token.kind() != &TokenKind::Punctuator(Punctuator::Assign))
             {
                 return Err(Error::general(
                     "Duplicate __proto__ fields are not allowed in object literals.",
diff --git a/core/parser/src/parser/function/mod.rs b/core/parser/src/parser/function/mod.rs
index acb78225430..44abc08a128 100644
--- a/core/parser/src/parser/function/mod.rs
+++ b/core/parser/src/parser/function/mod.rs
@@ -104,9 +104,10 @@ where
 
             params.push(next_param);
 
-            if cursor.peek(0, interner)?.map_or(true, |tok| {
-                tok.kind() == &TokenKind::Punctuator(Punctuator::CloseParen)
-            }) {
+            if cursor
+                .peek(0, interner)?
+                .is_none_or(|tok| tok.kind() == &TokenKind::Punctuator(Punctuator::CloseParen))
+            {
                 break;
             }
 
@@ -120,9 +121,10 @@ where
             }
 
             cursor.expect(Punctuator::Comma, "parameter list", interner)?;
-            if cursor.peek(0, interner)?.map_or(true, |tok| {
-                tok.kind() == &TokenKind::Punctuator(Punctuator::CloseParen)
-            }) {
+            if cursor
+                .peek(0, interner)?
+                .is_none_or(|tok| tok.kind() == &TokenKind::Punctuator(Punctuator::CloseParen))
+            {
                 break;
             }
         }
diff --git a/core/parser/src/parser/statement/mod.rs b/core/parser/src/parser/statement/mod.rs
index a04b97e866a..0a8abcff697 100644
--- a/core/parser/src/parser/statement/mod.rs
+++ b/core/parser/src/parser/statement/mod.rs
@@ -151,7 +151,6 @@ where
             TokenKind::Keyword((Keyword::For, _)) => {
                 ForStatement::new(self.allow_yield, self.allow_await, self.allow_return)
                     .parse(cursor, interner)
-                    .map(ast::Statement::from)
             }
             TokenKind::Keyword((Keyword::Return, _)) => {
                 if self.allow_return.0 {
diff --git a/core/parser/src/source/utf16.rs b/core/parser/src/source/utf16.rs
index 16434ce1d24..7daf1bbe48c 100644
--- a/core/parser/src/source/utf16.rs
+++ b/core/parser/src/source/utf16.rs
@@ -61,5 +61,5 @@ fn is_low_surrogate(b: u16) -> bool {
 }
 
 fn code_point_from_surrogates(high: u16, low: u16) -> u32 {
-    ((u32::from(high & 0x3ff)) << 10 | u32::from(low & 0x3ff)) + 0x1_0000
+    (((u32::from(high & 0x3ff)) << 10) | u32::from(low & 0x3ff)) + 0x1_0000
 }
diff --git a/core/parser/src/source/utf8.rs b/core/parser/src/source/utf8.rs
index 41c8404b1c5..8a595ff7e9c 100644
--- a/core/parser/src/source/utf8.rs
+++ b/core/parser/src/source/utf8.rs
@@ -43,12 +43,12 @@ impl<R: Read> ReadChar for UTF8Input<R> {
             // 5th bit in 0xE0 .. 0xEF is always clear, so `init` is still valid
             let z = self.next_byte()?.unwrap_or(0);
             let y_z = utf8_acc_cont_byte(u32::from(y & CONT_MASK), z);
-            ch = init << 12 | y_z;
+            ch = (init << 12) | y_z;
             if x >= 0xF0 {
                 // [x y z w] case
                 // use only the lower 3 bits of `init`
                 let w = self.next_byte()?.unwrap_or(0);
-                ch = (init & 7) << 18 | utf8_acc_cont_byte(y_z, w);
+                ch = ((init & 7) << 18) | utf8_acc_cont_byte(y_z, w);
             }
         };
 
diff --git a/core/string/src/lib.rs b/core/string/src/lib.rs
index b436b2e56c1..88af1352e03 100644
--- a/core/string/src/lib.rs
+++ b/core/string/src/lib.rs
@@ -970,13 +970,7 @@ impl From<JsStr<'_>> for JsString {
 impl From<&[JsString]> for JsString {
     #[inline]
     fn from(value: &[JsString]) -> Self {
-        Self::concat_array(
-            &value
-                .iter()
-                .map(Self::as_str)
-                .map(Into::into)
-                .collect::<Vec<_>>()[..],
-        )
+        Self::concat_array(&value.iter().map(Self::as_str).collect::<Vec<_>>()[..])
     }
 }