Fix ICE caused by at-expanding argument 0 instead of removing it early

2 files changed, 11 insertions, 2 deletions

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());