From 3afc004845b36d18009718fe8d5179adfa1ca2ea Mon Sep 17 00:00:00 2001
From: Antoine Martin <antoine97.martin@gmail.com>
Date: Mon, 5 Oct 2020 17:55:14 +0200
Subject: [PATCH] Show available profiles on error

---
 src/bootstrap/flags.rs | 9 ++++++++-
 src/bootstrap/setup.rs | 4 ++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/bootstrap/flags.rs b/src/bootstrap/flags.rs
index 2c1e361fae4c..d1f256d6dd09 100644
--- a/src/bootstrap/flags.rs
+++ b/src/bootstrap/flags.rs
@@ -542,7 +542,14 @@ Arguments:
                         |path| format!("{} is not a valid UTF8 string", path.to_string_lossy())
                     ));
 
-                    profile_string.parse().expect("unknown profile")
+                    profile_string.parse().unwrap_or_else(|_| {
+                        eprintln!("error: unknown profile {}", profile_string);
+                        eprintln!("help: the available profiles are:");
+                        for choice in Profile::all() {
+                            eprintln!("- {}", choice);
+                        }
+                        std::process::exit(1);
+                    })
                 } else {
                     t!(crate::setup::interactive_path())
                 };
diff --git a/src/bootstrap/setup.rs b/src/bootstrap/setup.rs
index cbbb406cd167..0d2945c3c396 100644
--- a/src/bootstrap/setup.rs
+++ b/src/bootstrap/setup.rs
@@ -18,6 +18,10 @@ impl Profile {
     fn include_path(&self, src_path: &Path) -> PathBuf {
         PathBuf::from(format!("{}/src/bootstrap/defaults/config.{}.toml", src_path.display(), self))
     }
+
+    pub fn all() -> impl Iterator<Item = Self> {
+        [Profile::Compiler, Profile::Codegen, Profile::Library, Profile::User].iter().copied()
+    }
 }
 
 #[derive(Debug)]