4 files changed, 55 insertions, 7 deletions
diff --git a/library/alloc/src/ffi/mod.rs b/library/alloc/src/ffi/mod.rs
index 05a2763a225..1c408ace336 100644
--- a/library/alloc/src/ffi/mod.rs
+++ b/library/alloc/src/ffi/mod.rs
@@ -87,5 +87,5 @@ pub use self::c_str::CString;
 #[stable(feature = "alloc_c_string", since = "1.64.0")]
 pub use self::c_str::{FromVecWithNulError, IntoStringError, NulError};
 
-#[stable(feature = "c_str_module", since = "CURRENT_RUSTC_VERSION")]
+#[stable(feature = "c_str_module", since = "1.88.0")]
 pub mod c_str;
diff --git a/library/alloc/src/raw_vec/mod.rs b/library/alloc/src/raw_vec/mod.rs
index a989e5b55b3..3e006a2d1bd 100644
--- a/library/alloc/src/raw_vec/mod.rs
+++ b/library/alloc/src/raw_vec/mod.rs
@@ -287,7 +287,7 @@ impl<T, A: Allocator> RawVec<T, A> {
     }
 
     #[inline]
-    pub(crate) fn non_null(&self) -> NonNull<T> {
+    pub(crate) const fn non_null(&self) -> NonNull<T> {
         self.inner.non_null()
     }
 
diff --git a/library/alloc/src/string.rs b/library/alloc/src/string.rs
index cd9e04a915a..37614a7ca45 100644
--- a/library/alloc/src/string.rs
+++ b/library/alloc/src/string.rs
@@ -1832,7 +1832,7 @@ impl String {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_vec_string_slice", since = "1.87.0")]
     #[rustc_confusables("length", "size")]
-    #[cfg_attr(not(bootstrap), rustc_no_implicit_autorefs)]
+    #[rustc_no_implicit_autorefs]
     pub const fn len(&self) -> usize {
         self.vec.len()
     }
@@ -1852,7 +1852,7 @@ impl String {
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_vec_string_slice", since = "1.87.0")]
-    #[cfg_attr(not(bootstrap), rustc_no_implicit_autorefs)]
+    #[rustc_no_implicit_autorefs]
     pub const fn is_empty(&self) -> bool {
         self.len() == 0
     }
@@ -2826,7 +2826,54 @@ impl SpecToString for bool {
     }
 }
 
+macro_rules! impl_to_string {
+    ($($signed:ident, $unsigned:ident,)*) => {
+        $(
+        #[cfg(not(no_global_oom_handling))]
+        #[cfg(not(feature = "optimize_for_size"))]
+        impl SpecToString for $signed {
+            #[inline]
+            fn spec_to_string(&self) -> String {
+                const SIZE: usize = $signed::MAX.ilog(10) as usize + 1;
+                let mut buf = [core::mem::MaybeUninit::<u8>::uninit(); SIZE];
+                // Only difference between signed and unsigned are these 8 lines.
+                let mut out;
+                if *self < 0 {
+                    out = String::with_capacity(SIZE + 1);
+                    out.push('-');
+                } else {
+                    out = String::with_capacity(SIZE);
+                }
+
+                out.push_str(self.unsigned_abs()._fmt(&mut buf));
+                out
+            }
+        }
+        #[cfg(not(no_global_oom_handling))]
+        #[cfg(not(feature = "optimize_for_size"))]
+        impl SpecToString for $unsigned {
+            #[inline]
+            fn spec_to_string(&self) -> String {
+                const SIZE: usize = $unsigned::MAX.ilog(10) as usize + 1;
+                let mut buf = [core::mem::MaybeUninit::<u8>::uninit(); SIZE];
+
+                self._fmt(&mut buf).to_string()
+            }
+        }
+        )*
+    }
+}
+
+impl_to_string! {
+    i8, u8,
+    i16, u16,
+    i32, u32,
+    i64, u64,
+    isize, usize,
+}
+
 #[cfg(not(no_global_oom_handling))]
+#[cfg(feature = "optimize_for_size")]
 impl SpecToString for u8 {
     #[inline]
     fn spec_to_string(&self) -> String {
@@ -2846,6 +2893,7 @@ impl SpecToString for u8 {
 }
 
 #[cfg(not(no_global_oom_handling))]
+#[cfg(feature = "optimize_for_size")]
 impl SpecToString for i8 {
     #[inline]
     fn spec_to_string(&self) -> String {
diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs
index a97912304c8..59879f23d78 100644
--- a/library/alloc/src/vec/mod.rs
+++ b/library/alloc/src/vec/mod.rs
@@ -1816,10 +1816,10 @@ impl<T, A: Allocator> Vec<T, A> {
     /// [`as_ptr`]: Vec::as_ptr
     /// [`as_non_null`]: Vec::as_non_null
     #[unstable(feature = "box_vec_non_null", reason = "new API", issue = "130364")]
+    #[rustc_const_unstable(feature = "box_vec_non_null", reason = "new API", issue = "130364")]
     #[inline]
-    pub fn as_non_null(&mut self) -> NonNull<T> {
-        // SAFETY: A `Vec` always has a non-null pointer.
-        unsafe { NonNull::new_unchecked(self.as_mut_ptr()) }
+    pub const fn as_non_null(&mut self) -> NonNull<T> {
+        self.buf.non_null()
     }
 
     /// Returns a reference to the underlying allocator.