Fix printk by allocating and also fighting with macros

Author: geofft

src/lib.rs

@@ -1,5 +1,5 @@
 #![no_std]
-#![feature(alloc, global_allocator, allocator_api, const_fn, lang_items)]
+#![feature(alloc, global_allocator, allocator_api, const_fn, lang_items, use_extern_macros)]
 
 extern crate alloc;
 #[macro_use]
@@ -12,6 +12,8 @@ pub mod filesystem;
 pub mod printk;
 pub mod types;
 
+pub use alloc::format;
+
 pub use error::{Error, KernelResult};
 
 #[macro_export]

src/printk.rs

@@ -30,6 +30,6 @@ macro_rules! println {
         use ::core::fmt::Write;
         // TODO: Don't allocate!
         let s = format!(concat!("\x016", $fmt, "\n"), $($arg)*);
-        let _ = $crate::printk::KernelConsole.write_str(s);
+        let _ = $crate::printk::KernelConsole.write_str(&s);
     });
 }