Greatly simplify the driver

- Remove sysroot handling. Since rust-lang/rust#103660 this is detected automatically!
- Update to a newer toolchain; in particular `install_ice_hook` has changed its signature.
- Remove the wrapper code; it only matters for cargo plugins, but ubrustc only has an equivalent of clippy-driver, not cargo-clippy.

src/main.rs

@@ -9,11 +9,9 @@ use rustc_driver::Callbacks;
 use rustc_hir::def_id::LocalDefId;
 use rustc_interface::interface;
 use rustc_middle::mir::BorrowCheckResult;
-use rustc_middle::ty::query::{ExternProviders, Providers};
+use rustc_middle::query::{ExternProviders, Providers};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::Session;
-use std::ffi::OsStr;
-use std::path::{Path, PathBuf};
 
 struct UbrustcCallbacks;
 
@@ -37,93 +35,14 @@ fn not_a_borrowchecker(cx: TyCtxt<'_>, _: LocalDefId) -> &'_ BorrowCheckResult<'
 }
 
 fn main() {
-    rustc_driver::install_ice_hook();
+    rustc_driver::install_ice_hook("https://github.com/thomcc/ubrustc/issues/new", |_| ());
     rustc_driver::init_rustc_env_logger();
     std::process::exit(rustc_driver::catch_with_exit_code(move || {
-        let orig_args: Vec<String> = std::env::args().collect();
-
-        let sysroot_arg = arg_value(&orig_args, "--sysroot");
-        let have_sysroot_arg = sysroot_arg.is_some();
-        let sysroot = sysroot_arg
-            .map(ToString::to_string)
-            .or_else(|| sysroot().map(|p| p.display().to_string()))
-            .expect("Failed to find sysroot");
-
-        let mut args: Vec<String> = orig_args.clone();
-
-        if !have_sysroot_arg {
-            args.extend(["--sysroot".to_string(), sysroot.to_string()]);
-        }
-
-        let our_exe_filename = std::env::current_exe()
-            .ok()
-            .and_then(|p| p.file_stem().map(ToOwned::to_owned))
-            .unwrap_or_else(|| "ubrustc".into());
-
-        // This is probably wrong.
-        let wrapper_mode = orig_args
-            .get(1)
-            .map(std::path::Path::new)
-            .and_then(std::path::Path::file_stem)
-            .map_or(false, |name| {
-                name == our_exe_filename || name == "ubrustc" || name == "rustc"
-            });
-
-        if wrapper_mode {
-            args.remove(1);
-        }
+        let args: Vec<String> = std::env::args().collect();
         run_compiler(args, &mut UbrustcCallbacks);
     }))
 }
 
-fn arg_value<'a, T: AsRef<str>>(args: &'a [T], find_arg: &str) -> Option<&'a str> {
-    let mut args = args.iter().map(|s| s.as_ref());
-    while let Some(arg) = args.next() {
-        let mut arg = arg.splitn(2, '=');
-        if arg.next() != Some(find_arg) {
-            continue;
-        }
-
-        if let Some(a) = arg.next().or_else(|| args.next()) {
-            return Some(a);
-        }
-    }
-    None
-}
-
-fn sysroot() -> Option<PathBuf> {
-    fn rustup_sysroot<H: ?Sized + AsRef<OsStr>, T: ?Sized + AsRef<Path>>(
-        home: &H,
-        toolchain: &T,
-    ) -> PathBuf {
-        let mut path = PathBuf::from(home);
-        path.push("toolchains");
-        path.push(toolchain);
-        path
-    }
-    fn runtime_rustup_sysroot() -> Option<PathBuf> {
-        let home = std::env::var_os("RUSTUP_HOME")?;
-        let toolchain = std::env::var_os("RUSTUP_TOOLCHAIN")?;
-        Some(rustup_sysroot(&home, &toolchain))
-    }
-    fn compiletime_rustup_sysroot() -> Option<PathBuf> {
-        let home: &str = option_env!("RUSTUP_HOME")?;
-        let toolchain: &str = option_env!("RUSTUP_TOOLCHAIN")?;
-        Some(rustup_sysroot(&home, &toolchain))
-    }
-    fn rustc_on_path_sysroot() -> Option<PathBuf> {
-        std::process::Command::new("rustc")
-            .arg("--print=sysroot")
-            .output()
-            .ok()
-            .and_then(|out| String::from_utf8(out.stdout).ok())
-            .map(|s| PathBuf::from(s.trim()))
-    }
-    runtime_rustup_sysroot()
-        .or_else(rustc_on_path_sysroot)
-        .or_else(compiletime_rustup_sysroot)
-}
-
 fn run_compiler<CB: Callbacks + Send>(mut args: Vec<String>, callbacks: &mut CB) -> ! {
     args.splice(1..1, std::iter::once("--cfg=ubrustc".to_string()));
     std::process::exit(rustc_driver::catch_with_exit_code(move || {