Return ExitCode from rustc_driver::main

This makes rustc simply return an exit code from main rather than calling `std::process::exit` with an exit code. This means that drops run normally and the process exits cleanly.

Also instead of hard coding success and failure codes this uses `ExitCode::SUCCESS` and `ExitCode::FAILURE`, which in turn effectively uses `libc::EXIT_SUCCESS` and `libc::EXIT_FAILURE` (via std). These are `0` and `1` respectively for all currently supported host platforms so it doesn't actually change the exit code.

compiler/rustc/src/main.rs

@@ -3,6 +3,8 @@
 // Several crates are depended upon but unused so that they are present in the sysroot
 #![expect(unused_crate_dependencies)]
 
+use std::process::ExitCode;
+
 // A note about jemalloc: rustc uses jemalloc when built for CI and
 // distribution. The obvious way to do this is with the `#[global_allocator]`
 // mechanism. However, for complicated reasons (see
@@ -38,6 +40,6 @@
 #[cfg(feature = "jemalloc")]
 use tikv_jemalloc_sys as _;
 
-fn main() {
+fn main() -> ExitCode {
     rustc_driver::main()
 }

compiler/rustc_driver_impl/src/lib.rs

@@ -20,7 +20,7 @@ use std::fs::{self, File};
 use std::io::{self, IsTerminal, Read, Write};
 use std::panic::{self, PanicHookInfo};
 use std::path::{Path, PathBuf};
-use std::process::{self, Command, Stdio};
+use std::process::{Command, ExitCode, Stdio, Termination};
 use std::sync::OnceLock;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::time::Instant;
@@ -1382,10 +1382,10 @@ fn parse_crate_attrs<'a>(sess: &'a Session) -> PResult<'a, ast::AttrVec> {
 
 /// Variant of `catch_fatal_errors` for the `interface::Result` return type
 /// that also computes the exit code.
-pub fn catch_with_exit_code(f: impl FnOnce()) -> i32 {
+pub fn catch_with_exit_code<T: Termination>(f: impl FnOnce() -> T) -> ExitCode {
     match catch_fatal_errors(f) {
-        Ok(()) => EXIT_SUCCESS,
-        _ => EXIT_FAILURE,
+        Ok(status) => status.report(),
+        _ => ExitCode::FAILURE,
     }
 }
 
@@ -1670,7 +1670,7 @@ pub fn install_ctrlc_handler() {
     .expect("Unable to install ctrlc handler");
 }
 
-pub fn main() -> ! {
+pub fn main() -> ExitCode {
     let start_time = Instant::now();
     let start_rss = get_resident_set_size();
 
@@ -1690,5 +1690,5 @@ pub fn main() -> ! {
         print_time_passes_entry("total", start_time.elapsed(), start_rss, end_rss, format);
     }
 
-    process::exit(exit_code)
+    exit_code
 }

src/librustdoc/lib.rs

@@ -71,7 +71,7 @@ extern crate tikv_jemalloc_sys as _;
 use std::env::{self, VarError};
 use std::io::{self, IsTerminal};
 use std::path::Path;
-use std::process;
+use std::process::ExitCode;
 
 use rustc_errors::DiagCtxtHandle;
 use rustc_hir::def_id::LOCAL_CRATE;
@@ -126,7 +126,7 @@ mod visit;
 mod visit_ast;
 mod visit_lib;
 
-pub fn main() {
+pub fn main() -> ExitCode {
     let mut early_dcx = EarlyDiagCtxt::new(ErrorOutputType::default());
 
     rustc_driver::install_ice_hook(
@@ -164,11 +164,10 @@ pub fn main() {
         Err(error) => early_dcx.early_fatal(error.to_string()),
     }
 
-    let exit_code = rustc_driver::catch_with_exit_code(|| {
+    rustc_driver::catch_with_exit_code(|| {
         let at_args = rustc_driver::args::raw_args(&early_dcx);
         main_args(&mut early_dcx, &at_args);
-    });
-    process::exit(exit_code);
+    })
 }
 
 fn init_logging(early_dcx: &EarlyDiagCtxt) {

src/tools/clippy/src/driver.rs

@@ -32,7 +32,7 @@ use std::env;
 use std::fs::read_to_string;
 use std::io::Write as _;
 use std::path::Path;
-use std::process::exit;
+use std::process::ExitCode;
 
 /// If a command-line option matches `find_arg`, then apply the predicate `pred` on its value. If
 /// true, then return it. The parameter is assumed to be either `--arg=value` or `--arg value`.
@@ -182,15 +182,17 @@ impl rustc_driver::Callbacks for ClippyCallbacks {
     }
 }
 
-fn display_help() {
+fn display_help() -> ExitCode {
     if writeln!(&mut anstream::stdout().lock(), "{}", help_message()).is_err() {
-        exit(rustc_driver::EXIT_FAILURE);
+        ExitCode::FAILURE
+    } else {
+        ExitCode::SUCCESS
     }
 }
 
 const BUG_REPORT_URL: &str = "https://github.com/rust-lang/rust-clippy/issues/new?template=ice.yml";
 
-pub fn main() {
+pub fn main() -> ExitCode {
     let early_dcx = EarlyDiagCtxt::new(ErrorOutputType::default());
 
     rustc_driver::init_rustc_env_logger(&early_dcx);
@@ -203,7 +205,7 @@ pub fn main() {
         dcx.handle().note(format!("Clippy version: {version_info}"));
     });
 
-    exit(rustc_driver::catch_with_exit_code(move || {
+    rustc_driver::catch_with_exit_code(move || {
         let mut orig_args = rustc_driver::args::raw_args(&early_dcx);
 
         let has_sysroot_arg = |args: &mut [String]| -> bool {
@@ -246,15 +248,15 @@ pub fn main() {
             pass_sysroot_env_if_given(&mut args, sys_root_env);
 
             rustc_driver::run_compiler(&args, &mut DefaultCallbacks);
-            return;
+            return ExitCode::SUCCESS;
         }
 
         if orig_args.iter().any(|a| a == "--version" || a == "-V") {
             let version_info = rustc_tools_util::get_version_info!();
 
-            match writeln!(&mut anstream::stdout().lock(), "{version_info}") {
-                Ok(()) => exit(rustc_driver::EXIT_SUCCESS),
-                Err(_) => exit(rustc_driver::EXIT_FAILURE),
+            return match writeln!(&mut anstream::stdout().lock(), "{version_info}") {
+                Ok(()) => ExitCode::SUCCESS,
+                Err(_) => ExitCode::FAILURE,
             }
         }
 
@@ -268,8 +270,7 @@ pub fn main() {
         }
 
         if !wrapper_mode && (orig_args.iter().any(|a| a == "--help" || a == "-h") || orig_args.len() == 1) {
-            display_help();
-            exit(0);
+            return display_help();
         }
 
         let mut args: Vec<String> = orig_args.clone();
@@ -311,7 +312,8 @@ pub fn main() {
         } else {
             rustc_driver::run_compiler(&args, &mut RustcCallbacks { clippy_args_var });
         }
-    }))
+        ExitCode::SUCCESS
+    })
 }
 
 #[must_use]

src/tools/rustdoc/main.rs

@@ -1,6 +1,8 @@
 // We need this feature as it changes `dylib` linking behavior and allows us to link to `rustc_driver`.
 #![feature(rustc_private)]
 
-fn main() {
+use std::process::ExitCode;
+
+fn main() -> ExitCode {
     rustdoc::main()
 }

tests/ui-fulldeps/obtain-borrowck.rs

@@ -28,6 +28,7 @@ extern crate rustc_session;
 
 use std::cell::RefCell;
 use std::collections::HashMap;
+use std::process::ExitCode;
 use std::thread_local;
 
 use rustc_borrowck::consumers::{self, BodyWithBorrowckFacts, ConsumerOptions};
@@ -42,16 +43,15 @@ use rustc_middle::ty::TyCtxt;
 use rustc_middle::util::Providers;
 use rustc_session::Session;
 
-fn main() {
-    let exit_code = rustc_driver::catch_with_exit_code(move || {
+fn main() -> ExitCode {
+    rustc_driver::catch_with_exit_code(move || {
         let mut rustc_args: Vec<_> = std::env::args().collect();
         // We must pass -Zpolonius so that the borrowck information is computed.
         rustc_args.push("-Zpolonius".to_owned());
         let mut callbacks = CompilerCalls::default();
         // Call the Rust compiler with our callbacks.
         rustc_driver::run_compiler(&rustc_args, &mut callbacks);
-    });
-    std::process::exit(exit_code);
+    })
 }
 
 #[derive(Default)]