remove dependency from lazy_static

- requires PR rust-lang/rust#71839
- consequently, the latest nightly compiler has to be used

Cargo.toml

@@ -34,7 +34,6 @@ acpi = []
 bitflags = "1.2"
 #cfg-if = "0.1"
 #byteorder = { version = "1.0", default-features = false }
-lazy_static = { version = "1.4.0", default-features = false, features = ["spin_no_std"] }
 num-derive = "0.3"
 
 [dependencies.num]

src/lib.rs

@@ -24,6 +24,7 @@
 #![allow(clippy::forget_copy)]
 #![feature(abi_x86_interrupt)]
 #![feature(allocator_api)]
+#![feature(const_btree_new)]
 #![feature(const_fn)]
 #![feature(lang_items)]
 #![feature(linkage)]
@@ -51,8 +52,6 @@ extern crate multiboot;
 extern crate x86;
 #[macro_use]
 extern crate log;
-#[macro_use]
-extern crate lazy_static;
 extern crate num;
 #[macro_use]
 extern crate num_derive;

src/syscalls/fs.rs

@@ -51,9 +51,7 @@ TODO:
 */
 
 // TODO: lazy static could be replaced with explicit init on OS boot.
-lazy_static! {
-	pub static ref FILESYSTEM: Spinlock<Filesystem> = Spinlock::new(Filesystem::new());
-}
+pub static FILESYSTEM: Spinlock<Filesystem> = Spinlock::new(Filesystem::new());
 
 pub struct Filesystem {
 	// Keep track of mount-points
@@ -64,7 +62,7 @@ pub struct Filesystem {
 }
 
 impl Filesystem {
-	pub fn new() -> Self {
+	pub const fn new() -> Self {
 		Self {
 			mounts: BTreeMap::new(),
 			files: BTreeMap::new(),