drop support of older nightlies

Minor version has been bumped to v0.4.0 so we can stop supporting them

This also drop the chrono dependency, which some people have been running into problems with.

closes #60

Cargo.toml

@@ -16,7 +16,3 @@ r0 = "0.2.1"
 [features]
 # provides a panic_fmt implementation that calls the abort instruction (`udf 0xfe`)
 abort-on-panic = []
-
-[build-dependencies]
-rustc_version = "0.2.1"
-chrono = "0.4.0"

build.rs

@@ -1,22 +1,9 @@
-extern crate chrono;
-extern crate rustc_version;
-
 use std::env;
 use std::fs::File;
 use std::io::Write;
 use std::path::PathBuf;
 
-use chrono::NaiveDate;
-
 fn main() {
- let meta = rustc_version::version_meta().unwrap();
- if meta.channel == rustc_version::Channel::Dev
- || meta.commit_date.unwrap().parse::<NaiveDate>().unwrap()
- > NaiveDate::from_ymd(2017, 12, 26)
- {
- println!("cargo:rustc-cfg=has_termination_lang")
- }
-
  let target = env::var("TARGET").unwrap();
 
  has_fpu(&target);

src/lang_items.rs

@@ -24,7 +24,6 @@ unsafe extern "C" fn panic_fmt(_: ::core::fmt::Arguments, _: &'static str, _: u3
 // The final piece is that the entry point of our program, the reset handler,
 // has to call `rustc_main`. That's covered by the `reset_handler` function in
 // root of this crate.
-#[cfg(has_termination_lang)]
 #[lang = "start"]
 extern "C" fn start<T>(main: fn() -> T, _argc: isize, _argv: *const *const u8) -> isize
 where
@@ -35,21 +34,11 @@ where
  0
 }
 
-#[cfg(not(has_termination_lang))]
-#[lang = "start"]
-extern "C" fn start(main: fn(), _argc: isize, _argv: *const *const u8) -> isize {
- main();
-
- 0
-}
-
 #[lang = "termination"]
-#[cfg(has_termination_lang)]
 pub trait Termination {
  fn report(self) -> i32;
 }
 
-#[cfg(has_termination_lang)]
 impl Termination for () {
  fn report(self) -> i32 {
  0