From 6240d4518930bdf20b44109e55d047eec3221c9a Mon Sep 17 00:00:00 2001
From: dekrain <dawidkrainski8@gmail.com>
Date: Mon, 13 Mar 2023 18:28:59 +0100
Subject: [PATCH] Fix ICE caused by at-expanding argument 0 instead of removing
 it early

---
 compiler/rustc_driver_impl/src/args.rs |  3 +++
 compiler/rustc_driver_impl/src/lib.rs  | 13 ++++++++++---
 src/librustdoc/config.rs               |  1 -
 src/librustdoc/lib.rs                  | 12 +++++++++++-
 4 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/compiler/rustc_driver_impl/src/args.rs b/compiler/rustc_driver_impl/src/args.rs
index 42c97cc6a9d..5ddacc38863 100644
--- a/compiler/rustc_driver_impl/src/args.rs
+++ b/compiler/rustc_driver_impl/src/args.rs
@@ -18,6 +18,9 @@ fn arg_expand(arg: String) -> Result<Vec<String>, Error> {
     }
 }
 
+/// **Note:** This function doesn't interpret argument 0 in any special way.
+/// If this function is intended to be used with command line arguments,
+/// `argv[0]` must be removed prior to calling it manually.
 pub fn arg_expand_all(at_args: &[String]) -> Vec<String> {
     let mut args = Vec::new();
     for arg in at_args {
diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index 555917c8b5e..88f3b24bc98 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -237,6 +237,16 @@ fn run_compiler(
         Box<dyn FnOnce(&config::Options) -> Box<dyn CodegenBackend> + Send>,
     >,
 ) -> interface::Result<()> {
+    // Throw away the first argument, the name of the binary.
+    // In case of at_args being empty, as might be the case by
+    // passing empty argument array to execve under some platforms,
+    // just use an empty slice.
+    //
+    // This situation was possible before due to arg_expand_all being
+    // called before removing the argument, enabling a crash by calling
+    // the compiler with @empty_file as argv[0] and no more arguments.
+    let at_args = at_args.get(1..).unwrap_or_default();
+
     let args = args::arg_expand_all(at_args);
 
     let Some(matches) = handle_options(&args) else { return Ok(()) };
@@ -993,9 +1003,6 @@ pub fn print_flag_list<T>(
 /// So with all that in mind, the comments below have some more detail about the
 /// contortions done here to get things to work out correctly.
 pub fn handle_options(args: &[String]) -> Option<getopts::Matches> {
-    // Throw away the first argument, the name of the binary
-    let args = &args[1..];
-
     if args.is_empty() {
         // user did not write `-v` nor `-Z unstable-options`, so do not
         // include that extra information.
diff --git a/src/librustdoc/config.rs b/src/librustdoc/config.rs
index 2c514a0c826..22356229d05 100644
--- a/src/librustdoc/config.rs
+++ b/src/librustdoc/config.rs
@@ -321,7 +321,6 @@ impl Options {
         matches: &getopts::Matches,
         args: Vec<String>,
     ) -> Result<(Options, RenderOptions), i32> {
-        let args = &args[1..];
         // Check for unstable options.
         nightly_options::check_nightly_options(matches, &opts());
 
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 4fcf0873600..da32d429dac 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -703,13 +703,23 @@ fn run_renderer<'tcx, T: formats::FormatRenderer<'tcx>>(
 }
 
 fn main_args(at_args: &[String]) -> MainResult {
+    // Throw away the first argument, the name of the binary.
+    // In case of at_args being empty, as might be the case by
+    // passing empty argument array to execve under some platforms,
+    // just use an empty slice.
+    //
+    // This situation was possible before due to arg_expand_all being
+    // called before removing the argument, enabling a crash by calling
+    // the compiler with @empty_file as argv[0] and no more arguments.
+    let at_args = at_args.get(1..).unwrap_or_default();
+
     let args = rustc_driver::args::arg_expand_all(at_args);
 
     let mut options = getopts::Options::new();
     for option in opts() {
         (option.apply)(&mut options);
     }
-    let matches = match options.parse(&args[1..]) {
+    let matches = match options.parse(&args) {
         Ok(m) => m,
         Err(err) => {
             early_error(ErrorOutputType::default(), &err.to_string());