From 7edd1810b41e239ea59b22a73a87f8c377d2293f Mon Sep 17 00:00:00 2001
From: Joshua Nelson <jyn514@gmail.com>
Date: Fri, 25 Dec 2020 19:04:50 -0500
Subject: Don't panic when an external crate can't be resolved

This isn't actually a bug, it can occur when rustdoc tries to resolve a
crate that isn't used in the main code.
---
 src/librustdoc/core.rs | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

(limited to 'src/librustdoc')

diff --git a/src/librustdoc/core.rs b/src/librustdoc/core.rs
index 7e85342ac7d..819dc06845f 100644
--- a/src/librustdoc/core.rs
+++ b/src/librustdoc/core.rs
@@ -428,16 +428,15 @@ crate fn create_resolver<'a>(
         sess.time("load_extern_crates", || {
             for extern_name in &extern_names {
                 debug!("loading extern crate {}", extern_name);
-                resolver
+                if let Err(()) = resolver
                     .resolve_str_path_error(
                         DUMMY_SP,
                         extern_name,
                         TypeNS,
                         LocalDefId { local_def_index: CRATE_DEF_INDEX }.to_def_id(),
-                    )
-                    .unwrap_or_else(|()| {
-                        panic!("Unable to resolve external crate {}", extern_name)
-                    });
+                  ) {
+                    warn!("unable to resolve external crate {} (do you have an unused `--extern` crate?)", extern_name)
+                  }
             }
         });
     });
-- 
cgit 1.4.1-3-g733a5