Use field init shorthand where possible

Field init shorthand allows writing initializers like `tcx: tcx` as
`tcx`. The compiler already uses it extensively. Fix the last few places
where it isn't yet used.

Author: joshtriplett

compiler/rustc_const_eval/src/interpret/projection.rs

@@ -325,7 +325,7 @@ where
         let actual_to = if from_end {
             if from.checked_add(to).is_none_or(|to| to > len) {
                 // This can only be reached in ConstProp and non-rustc-MIR.
-                throw_ub!(BoundsCheckFailed { len: len, index: from.saturating_add(to) });
+                throw_ub!(BoundsCheckFailed { len, index: from.saturating_add(to) });
             }
             len.checked_sub(to).unwrap()
         } else {

compiler/rustc_lint/src/impl_trait_overcaptures.rs

@@ -177,7 +177,7 @@ fn check_fn(tcx: TyCtxt<'_>, parent_def_id: LocalDefId) {
         // Lazily compute these two, since they're likely a bit expensive.
         variances: LazyCell::new(|| {
             let mut functional_variances = FunctionalVariances {
-                tcx: tcx,
+                tcx,
                 variances: FxHashMap::default(),
                 ambient_variance: ty::Covariant,
                 generics: tcx.generics_of(parent_def_id),

compiler/rustc_parse/src/parser/pat.rs

@@ -1648,7 +1648,7 @@ impl<'a> Parser<'a> {
                 ident: prev_field,
             })
         } else {
-            self.dcx().create_err(AtInStructPattern { span: span })
+            self.dcx().create_err(AtInStructPattern { span })
         }
     }
 

compiler/rustc_type_ir/src/elaborate.rs

@@ -72,7 +72,7 @@ impl<I: Interner> Elaboratable<I> for ClauseWithSupertraitSpan<I> {
         _parent_trait_pred: crate::Binder<I, crate::TraitPredicate<I>>,
         _index: usize,
     ) -> Self {
-        ClauseWithSupertraitSpan { pred: clause.as_predicate(), supertrait_span: supertrait_span }
+        ClauseWithSupertraitSpan { pred: clause.as_predicate(), supertrait_span }
     }
 }
 

library/alloc/src/rc.rs

@@ -795,7 +795,7 @@ impl<T, A: Allocator> Rc<T, A> {
         let uninit_ptr: NonNull<_> = (unsafe { &mut *uninit_raw_ptr }).into();
         let init_ptr: NonNull<RcInner<T>> = uninit_ptr.cast();
 
-        let weak = Weak { ptr: init_ptr, alloc: alloc };
+        let weak = Weak { ptr: init_ptr, alloc };
 
         // It's important we don't give up ownership of the weak pointer, or
         // else the memory might be freed by the time `data_fn` returns. If

library/alloc/src/sync.rs

@@ -784,7 +784,7 @@ impl<T, A: Allocator> Arc<T, A> {
         let uninit_ptr: NonNull<_> = (unsafe { &mut *uninit_raw_ptr }).into();
         let init_ptr: NonNull<ArcInner<T>> = uninit_ptr.cast();
 
-        let weak = Weak { ptr: init_ptr, alloc: alloc };
+        let weak = Weak { ptr: init_ptr, alloc };
 
         // It's important we don't give up ownership of the weak pointer, or
         // else the memory might be freed by the time `data_fn` returns. If

library/core/src/task/wake.rs

@@ -322,7 +322,7 @@ impl<'a> ContextBuilder<'a> {
         // SAFETY: LocalWaker is just Waker without thread safety
         let local_waker = unsafe { transmute(waker) };
         Self {
-            waker: waker,
+            waker,
             local_waker,
             ext: ExtData::None(()),
             _marker: PhantomData,

library/std/src/sys/pal/hermit/fs.rs

@@ -135,7 +135,7 @@ impl FileAttr {
             S_IFREG => DT_REG,
             _ => DT_UNKNOWN,
         };
-        FileType { mode: mode }
+        FileType { mode }
     }
 }
 

library/std/src/sys/pal/hermit/thread.rs

@@ -43,7 +43,7 @@ impl Thread {
             }
             Err(io::const_error!(io::ErrorKind::Uncategorized, "Unable to create thread!"))
         } else {
-            Ok(Thread { tid: tid })
+            Ok(Thread { tid })
         };
 
         extern "C" fn thread_start(main: usize) {

library/std/src/sys/pal/hermit/time.rs

@@ -22,7 +22,7 @@ impl Timespec {
     const fn new(tv_sec: i64, tv_nsec: i32) -> Timespec {
         assert!(tv_nsec >= 0 && tv_nsec < NSEC_PER_SEC);
         // SAFETY: The assert above checks tv_nsec is within the valid range
-        Timespec { t: timespec { tv_sec: tv_sec, tv_nsec: tv_nsec } }
+        Timespec { t: timespec { tv_sec, tv_nsec } }
     }
 
     fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {