From d4c9fe7549f29ca573f5a58ac94eacd662cd1421 Mon Sep 17 00:00:00 2001
From: Igor Aleksanov <popzxc@yandex.ru>
Date: Sun, 20 Jun 2021 08:25:30 +0300
Subject: [PATCH 1/3] Improve visibility&helpfulness of the 'found multiple
 rlibs' error

---
 tests/compile-test.rs | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tests/compile-test.rs b/tests/compile-test.rs
index 7d266a36b..72905bd94 100644
--- a/tests/compile-test.rs
+++ b/tests/compile-test.rs
@@ -48,7 +48,13 @@ fn third_party_crates() -> String {
                     && name.rsplit('.').next().map(|ext| ext.eq_ignore_ascii_case("rlib")) == Some(true)
                 {
                     if let Some(old) = crates.insert(dep, path.clone()) {
-                        panic!("Found multiple rlibs for crate `{}`: `{:?}` and `{:?}", dep, old, path);
+                        panic!(
+                            "\n---------------------------------------------------\n\n \
+                            Found multiple rlibs for crate `{}`: `{:?}` and `{:?}`.\n \
+                            Probably, you need to run `cargo clean` before running tests again.\n \
+                            \n---------------------------------------------------\n",
+                            dep, old, path
+                        );
                     }
                     break;
                 }

From faa2fa7490423b30362b44034e9336c469556b6b Mon Sep 17 00:00:00 2001
From: Igor Aleksanov <popzxc@yandex.ru>
Date: Sun, 20 Jun 2021 08:32:43 +0300
Subject: [PATCH 2/3] Improve appearance

---
 tests/compile-test.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/compile-test.rs b/tests/compile-test.rs
index 72905bd94..8640cfb96 100644
--- a/tests/compile-test.rs
+++ b/tests/compile-test.rs
@@ -52,6 +52,7 @@ fn third_party_crates() -> String {
                             "\n---------------------------------------------------\n\n \
                             Found multiple rlibs for crate `{}`: `{:?}` and `{:?}`.\n \
                             Probably, you need to run `cargo clean` before running tests again.\n \
+                            \nFor details on that error see https://github.com/rust-lang/rust-clippy/issues/7343 \
                             \n---------------------------------------------------\n",
                             dep, old, path
                         );

From 310a2043066212e4bc702d2a79dc50a1312ac94d Mon Sep 17 00:00:00 2001
From: Igor Aleksanov <popzxc@yandex.ru>
Date: Mon, 21 Jun 2021 06:57:57 +0300
Subject: [PATCH 3/3] Provide different message for bootstrapped compiler

---
 tests/compile-test.rs | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/tests/compile-test.rs b/tests/compile-test.rs
index 8640cfb96..caa19e39c 100644
--- a/tests/compile-test.rs
+++ b/tests/compile-test.rs
@@ -48,13 +48,23 @@ fn third_party_crates() -> String {
                     && name.rsplit('.').next().map(|ext| ext.eq_ignore_ascii_case("rlib")) == Some(true)
                 {
                     if let Some(old) = crates.insert(dep, path.clone()) {
+                        // Check which action should be done in order to remove compiled deps.
+                        // If pre-installed version of compiler is used, `cargo clean` will do.
+                        // Otherwise (for bootstrapped compiler), the dependencies directory
+                        // must be removed manually.
+                        let suggested_action = if std::env::var_os("RUSTC_BOOTSTRAP").is_some() {
+                            "remove the stageN-tools directory"
+                        } else {
+                            "run `cargo clean`"
+                        };
+
                         panic!(
                             "\n---------------------------------------------------\n\n \
                             Found multiple rlibs for crate `{}`: `{:?}` and `{:?}`.\n \
-                            Probably, you need to run `cargo clean` before running tests again.\n \
+                            Probably, you need to {} before running tests again.\n \
                             \nFor details on that error see https://github.com/rust-lang/rust-clippy/issues/7343 \
                             \n---------------------------------------------------\n",
-                            dep, old, path
+                            dep, old, path, suggested_action
                         );
                     }
                     break;