Make everything compile on stable

[tomaka]

Very long-term issue.

[tomaka]

The list of the Rust nightly-only features being used can be found there:

redshirt/kernel/standalone/src/main.rs

Lines 20 to 29 in 8b63595

	#![feature(allocator_api)] // TODO: https://github.com/rust-lang/rust/issues/32838
	#![feature(alloc_error_handler)] // TODO: https://github.com/rust-lang/rust/issues/66741
	#![feature(asm)] // TODO: https://github.com/rust-lang/rust/issues/72016
	#![feature(core_intrinsics)]
	#![feature(const_if_match)] // TODO: https://github.com/rust-lang/rust/issues/49146
	#![feature(global_asm)] // TODO: https://github.com/rust-lang/rust/issues/35119
	#![feature(llvm_asm)] // TODO: replace all occurrences of `llvm_asm!` with `asm!`
	#![feature(naked_functions)] // TODO: https://github.com/rust-lang/rust/issues/32408
	#![feature(panic_info_message)] // TODO: https://github.com/rust-lang/rust/issues/66745
	#![cfg_attr(target_arch = "x86_64", feature(abi_x86_interrupt))] // TODO: https://github.com/rust-lang/rust/issues/40180

And there:

redshirt/core-proc-macros/src/lib.rs

Line 16 in e15f382

#![cfg_attr(feature = "nightly", feature(proc_macro_span))] // TODO: https://github.com/rust-lang/rust/issues/54725

(these links point to the latest commit at this time, but this list can obviously evolve over time).

[tomaka]

const_if_match has just been stabilized.

[tomaka]

Another usage is here:

redshirt/kernel/standalone-builder/src/build.rs

Line 150 in 283fd24

.args(&["-Z", "build-std=core,alloc"]) // TODO: nightly only; cc https://github.com/tomaka/redshirt/issues/300

cc https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#build-std
https://github.com/rust-lang/wg-cargo-std-aware

[SamuelMarks]

Additionally:

• start is nightly Tracking issue for the start feature rust-lang/rust#29633 and used at programs/stub/src/main.rs#L22

• asm_const is nightly Tracking Issue for asm_const rust-lang/rust#93332 and used at kernel-standalone-builder/src/build.rs#L186

• asm_sym is nightly Tracking Issue for asm_sym rust-lang/rust#93333 and used at kernel/standalone/src/lib.rs#L50