improve `filesearch::get_or_default_sysroot` r=ozkanonur

Signed-off-by: Onur Özkan <work@onurozkan.dev>

2 files changed, 16 insertions, 133 deletions

diff --git a/src/tools/clippy/src/driver.rs b/src/tools/clippy/src/driver.rs
index b12208ac62a..46afea2c4b5 100644
--- a/src/tools/clippy/src/driver.rs
+++ b/src/tools/clippy/src/driver.rs
@@ -23,8 +23,8 @@ use std::borrow::Cow;
 use std::env;
 use std::ops::Deref;
 use std::panic;
-use std::path::{Path, PathBuf};
-use std::process::{exit, Command};
+use std::path::Path;
+use std::process::exit;
 use std::sync::LazyLock;
 
 /// If a command-line option matches `find_arg`, then apply the predicate `pred` on its value. If
@@ -209,17 +209,6 @@ fn report_clippy_ice(info: &panic::PanicInfo<'_>, bug_report_url: &str) {
     interface::try_print_query_stack(&handler, num_frames);
 }
 
-fn toolchain_path(home: Option<String>, toolchain: Option<String>) -> Option<PathBuf> {
-    home.and_then(|home| {
-        toolchain.map(|toolchain| {
-            let mut path = PathBuf::from(home);
-            path.push("toolchains");
-            path.push(toolchain);
-            path
-        })
-    })
-}
-
 #[allow(clippy::too_many_lines)]
 pub fn main() {
     rustc_driver::init_rustc_env_logger();
@@ -227,51 +216,6 @@ pub fn main() {
     exit(rustc_driver::catch_with_exit_code(move || {
         let mut orig_args: Vec<String> = env::args().collect();
 
-        // Get the sysroot, looking from most specific to this invocation to the least:
-        // - command line
-        // - runtime environment
-        //    - SYSROOT
-        //    - RUSTUP_HOME, MULTIRUST_HOME, RUSTUP_TOOLCHAIN, MULTIRUST_TOOLCHAIN
-        // - sysroot from rustc in the path
-        // - compile-time environment
-        //    - SYSROOT
-        //    - RUSTUP_HOME, MULTIRUST_HOME, RUSTUP_TOOLCHAIN, MULTIRUST_TOOLCHAIN
-        let sys_root_arg = arg_value(&orig_args, "--sysroot", |_| true);
-        let have_sys_root_arg = sys_root_arg.is_some();
-        let sys_root = sys_root_arg
-            .map(PathBuf::from)
-            .or_else(|| std::env::var("SYSROOT").ok().map(PathBuf::from))
-            .or_else(|| {
-                let home = std::env::var("RUSTUP_HOME")
-                    .or_else(|_| std::env::var("MULTIRUST_HOME"))
-                    .ok();
-                let toolchain = std::env::var("RUSTUP_TOOLCHAIN")
-                    .or_else(|_| std::env::var("MULTIRUST_TOOLCHAIN"))
-                    .ok();
-                toolchain_path(home, toolchain)
-            })
-            .or_else(|| {
-                Command::new("rustc")
-                    .arg("--print")
-                    .arg("sysroot")
-                    .output()
-                    .ok()
-                    .and_then(|out| String::from_utf8(out.stdout).ok())
-                    .map(|s| PathBuf::from(s.trim()))
-            })
-            .or_else(|| option_env!("SYSROOT").map(PathBuf::from))
-            .or_else(|| {
-                let home = option_env!("RUSTUP_HOME")
-                    .or(option_env!("MULTIRUST_HOME"))
-                    .map(ToString::to_string);
-                let toolchain = option_env!("RUSTUP_TOOLCHAIN")
-                    .or(option_env!("MULTIRUST_TOOLCHAIN"))
-                    .map(ToString::to_string);
-                toolchain_path(home, toolchain)
-            })
-            .map(|pb| pb.to_string_lossy().to_string())
-            .expect("need to specify SYSROOT env var during clippy compilation, or use rustup or multirust");
-
         // make "clippy-driver --rustc" work like a subcommand that passes further args to "rustc"
         // for example `clippy-driver --rustc --version` will print the rustc version that clippy-driver
         // uses
@@ -279,13 +223,7 @@ pub fn main() {
             orig_args.remove(pos);
             orig_args[0] = "rustc".to_string();
 
-            // if we call "rustc", we need to pass --sysroot here as well
-            let mut args: Vec<String> = orig_args.clone();
-            if !have_sys_root_arg {
-                args.extend(vec!["--sysroot".into(), sys_root]);
-            };
-
-            return rustc_driver::RunCompiler::new(&args, &mut DefaultCallbacks).run();
+            return rustc_driver::RunCompiler::new(&orig_args, &mut DefaultCallbacks).run();
         }
 
         if orig_args.iter().any(|a| a == "--version" || a == "-V") {
@@ -308,14 +246,6 @@ pub fn main() {
             exit(0);
         }
 
-        // this conditional check for the --sysroot flag is there so users can call
-        // `clippy_driver` directly
-        // without having to pass --sysroot or anything
-        let mut args: Vec<String> = orig_args.clone();
-        if !have_sys_root_arg {
-            args.extend(vec!["--sysroot".into(), sys_root]);
-        };
-
         let mut no_deps = false;
         let clippy_args_var = env::var("CLIPPY_ARGS").ok();
         let clippy_args = clippy_args_var
@@ -344,10 +274,11 @@ pub fn main() {
 
         let clippy_enabled = !cap_lints_allow && (!no_deps || in_primary_package);
         if clippy_enabled {
+            let mut args: Vec<String> = orig_args.clone();
             args.extend(clippy_args);
             rustc_driver::RunCompiler::new(&args, &mut ClippyCallbacks { clippy_args_var }).run()
         } else {
-            rustc_driver::RunCompiler::new(&args, &mut RustcCallbacks { clippy_args_var }).run()
+            rustc_driver::RunCompiler::new(&orig_args, &mut RustcCallbacks { clippy_args_var }).run()
         }
     }))
 }
diff --git a/src/tools/miri/src/bin/miri.rs b/src/tools/miri/src/bin/miri.rs
index bd01ea655dd..e673ea67dbc 100644
--- a/src/tools/miri/src/bin/miri.rs
+++ b/src/tools/miri/src/bin/miri.rs
@@ -216,76 +216,28 @@ fn init_late_loggers(tcx: TyCtxt<'_>) {
     }
 }
 
-/// Returns the "default sysroot" that Miri will use for host things if no `--sysroot` flag is set.
-/// Should be a compile-time constant.
-fn host_sysroot() -> Option<String> {
-    if option_env!("RUSTC_STAGE").is_some() {
-        // This is being built as part of rustc, and gets shipped with rustup.
-        // We can rely on the sysroot computation in librustc_session.
-        return None;
-    }
-    // For builds outside rustc, we need to ensure that we got a sysroot
-    // that gets used as a default.  The sysroot computation in librustc_session would
-    // end up somewhere in the build dir (see `get_or_default_sysroot`).
-    // Taken from PR <https://github.com/Manishearth/rust-clippy/pull/911>.
-    let home = option_env!("RUSTUP_HOME").or(option_env!("MULTIRUST_HOME"));
-    let toolchain = option_env!("RUSTUP_TOOLCHAIN").or(option_env!("MULTIRUST_TOOLCHAIN"));
-    Some(match (home, toolchain) {
-        (Some(home), Some(toolchain)) => {
-            // Check that at runtime, we are still in this toolchain (if there is any toolchain).
-            if let Some(toolchain_runtime) =
-                env::var_os("RUSTUP_TOOLCHAIN").or_else(|| env::var_os("MULTIRUST_TOOLCHAIN"))
-            {
-                if toolchain_runtime != toolchain {
-                    show_error!(
-                        "This Miri got built with local toolchain `{toolchain}`, but now is being run under a different toolchain. \n\
-                        Make sure to run Miri in the toolchain it got built with, e.g. via `cargo +{toolchain} miri`."
-                    )
-                }
-            }
-            format!("{home}/toolchains/{toolchain}")
-        }
-        _ => option_env!("RUST_SYSROOT")
-            .unwrap_or_else(|| {
-                show_error!(
-                    "To build Miri without rustup, set the `RUST_SYSROOT` env var at build time",
-                )
-            })
-            .to_owned(),
-    })
-}
-
 /// Execute a compiler with the given CLI arguments and callbacks.
 fn run_compiler(
     mut args: Vec<String>,
     target_crate: bool,
     callbacks: &mut (dyn rustc_driver::Callbacks + Send),
 ) -> ! {
-    // Make sure we use the right default sysroot. The default sysroot is wrong,
-    // because `get_or_default_sysroot` in `librustc_session` bases that on `current_exe`.
-    //
-    // Make sure we always call `host_sysroot` as that also does some sanity-checks
-    // of the environment we were built in and whether it matches what we are running in.
-    let host_default_sysroot = host_sysroot();
-    // Now see if we even need to set something.
-    let sysroot_flag = "--sysroot";
-    if !args.iter().any(|e| e == sysroot_flag) {
-        // No sysroot was set, let's see if we have a custom default we want to configure.
-        let default_sysroot = if target_crate {
+    if target_crate {
+        // Miri needs a custom sysroot for target crates.
+        // If no `--sysroot` is given, the `MIRI_SYSROOT` env var is consulted to find where
+        // that sysroot lives, and that is passed to rustc.
+        let sysroot_flag = "--sysroot";
+        if !args.iter().any(|e| e == sysroot_flag) {
             // Using the built-in default here would be plain wrong, so we *require*
             // the env var to make sure things make sense.
-            Some(env::var("MIRI_SYSROOT").unwrap_or_else(|_| {
+            let miri_sysroot = env::var("MIRI_SYSROOT").unwrap_or_else(|_| {
                 show_error!(
                     "Miri was invoked in 'target' mode without `MIRI_SYSROOT` or `--sysroot` being set"
-                )
-            }))
-        } else {
-            host_default_sysroot
-        };
-        if let Some(sysroot) = default_sysroot {
-            // We need to overwrite the default that librustc_session would compute.
+                    )
+            });
+
             args.push(sysroot_flag.to_owned());
-            args.push(sysroot);
+            args.push(miri_sysroot);
         }
     }