reexport hint from code

- minor rustfmt update.

src/code/mod.rs

@@ -1,6 +1,9 @@
 // devela::meta
 //
-//! Code generation and meta-programming.
+//! Code generation and meta-programming, extends
+//! `std::`[`hint`].
+//!
+//! [`hint`]: core::hint
 //
 
 /* contains always compiled items */

src/code/reexports.rs

@@ -10,3 +10,23 @@ pub use devela_macros::{cif, coalesce, compile, compile_attr};
 
 /// <span class="stab portability" title="re-exported from the `paste crate`">`paste`</span>
 pub use super::paste::paste;
+
+/* core::hint reexports */
+
+use super::reexport;
+
+reexport! { rust: core::hint, local_module: "code",
+    doc: "An identity function that hints to the compiler to be maximally
+        pessimistic about what black_box could do.",
+    black_box
+}
+reexport! { rust: core::hint, local_module: "code",
+    doc: "Emits a machine instruction to signal the processor that
+        it is running in a busy-wait spin-loop (“spin lock”).",
+    spin_loop
+}
+reexport! { rust: core::hint, local_module: "code",
+    doc: "Informs the compiler that the site which is calling this function
+        is not reachable, possibly enabling further optimizations.",
+    unreachable_unchecked
+}

src/text/ext/str.rs

@@ -101,6 +101,10 @@ impl StrExt for str {
     fn new_counter(buffer: &mut [u8], length: usize, separator: AsciiChar) -> &str {
         assert![buffer.len() >= length];
         if length == 0 {
+            // the cold path that returns an empty string slice
+            #[cold] #[inline] #[rustfmt::skip]
+            fn cold_empty_string() -> &'static str { "" }
+
             cold_empty_string()
         } else {
             let separator = separator.as_u8();
@@ -156,10 +160,3 @@ impl StrExt for str {
         }
     }
 }
-
-// the cold path that returns an empty string slice
-#[cold]
-#[inline]
-fn cold_empty_string() -> &'static str {
-    ""
-}