Rollup merge of rust-lang#103660 - ozkanonur:master, r=jyn514

improve `filesearch::get_or_default_sysroot`

`fn get_or_default_sysroot` is now improved and used in `miri` and `clippy`, and tests are still passing as they should. So we no longer need to implement custom workarounds/hacks to find sysroot in tools like miri/clippy.

Resolves rust-lang#98832

re-opened from rust-lang#103581

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
@@ -210,83 +210,21 @@ 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();
     LazyLock::force(&ICE_HOOK);
     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
         if let Some(pos) = orig_args.iter().position(|arg| arg == "--rustc") {
             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") {
@@ -309,14 +247,6 @@ 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
@@ -345,10 +275,11 @@ 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()
         }
     }))
 }