alloc: clean and ensure no_global_oom_handling builds are warning-free

library/alloc/src/boxed/thin.rs

@@ -3,7 +3,9 @@
 // by matthieu-m
 use crate::alloc::{self, Layout, LayoutError};
 use core::fmt::{self, Debug, Display, Formatter};
-use core::marker::{PhantomData, Unsize};
+use core::marker::PhantomData;
+#[cfg(not(no_global_oom_handling))]
+use core::marker::Unsize;
 use core::mem;
 use core::ops::{Deref, DerefMut};
 use core::ptr::Pointee;

library/alloc/src/raw_vec.rs

@@ -421,6 +421,7 @@ impl<T, A: Allocator> RawVec<T, A> {
         Ok(())
     }
 
+    #[cfg(not(no_global_oom_handling))]
     fn shrink(&mut self, cap: usize) -> Result<(), TryReserveError> {
         assert!(cap <= self.capacity(), "Tried to shrink to a larger capacity");
 

library/alloc/src/string.rs

@@ -46,9 +46,9 @@
 use core::char::{decode_utf16, REPLACEMENT_CHARACTER};
 use core::fmt;
 use core::hash;
+use core::iter::FusedIterator;
 #[cfg(not(no_global_oom_handling))]
-use core::iter::FromIterator;
-use core::iter::{from_fn, FusedIterator};
+use core::iter::{from_fn, FromIterator};
 #[cfg(not(no_global_oom_handling))]
 use core::ops::Add;
 #[cfg(not(no_global_oom_handling))]

library/alloc/src/vec/into_iter.rs

@@ -9,6 +9,7 @@ use core::iter::{
 };
 use core::marker::PhantomData;
 use core::mem::{self, ManuallyDrop};
+#[cfg(not(no_global_oom_handling))]
 use core::ops::Deref;
 use core::ptr::{self, NonNull};
 use core::slice::{self};
@@ -123,6 +124,7 @@ impl<T, A: Allocator> IntoIter<T, A> {
     }
 
     /// Forgets to Drop the remaining elements while still allowing the backing allocation to be freed.
+    #[cfg(not(no_global_oom_handling))]
     pub(crate) fn forget_remaining_elements(&mut self) {
         self.ptr = self.end;
     }

src/test/run-make-fulldeps/alloc-no-oom-handling/Makefile

@@ -1,4 +1,4 @@
 -include ../tools.mk
 
 all:
-	$(RUSTC) --edition=2021 --crate-type=rlib ../../../../library/alloc/src/lib.rs --cfg no_global_oom_handling
+	$(RUSTC) --edition=2021 -Dwarnings --crate-type=rlib ../../../../library/alloc/src/lib.rs --cfg no_global_oom_handling