From 48438ce1ae2a369f10287b94f8fa8074f91a9cab Mon Sep 17 00:00:00 2001
From: Roc Yu <rocyu@protonmail.com>
Date: Wed, 12 Jan 2022 15:57:46 -0500
Subject: [PATCH] Remove intermediate `collect`

---
 src/librustdoc/doctest.rs | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/librustdoc/doctest.rs b/src/librustdoc/doctest.rs
index ac24543929b..67d43fbf0bb 100644
--- a/src/librustdoc/doctest.rs
+++ b/src/librustdoc/doctest.rs
@@ -395,7 +395,7 @@ fn run_test(
             eprint!("{}", self.0);
         }
     }
-    let mut out_lines = str::from_utf8(&output.stderr)
+    let mut out = str::from_utf8(&output.stderr)
         .unwrap()
         .lines()
         .filter(|l| {
@@ -406,15 +406,15 @@ fn run_test(
                 true
             }
         })
-        .collect::<Vec<_>>();
+        .intersperse_with(|| "\n")
+        .collect::<String>();
 
     // Add a \n to the end to properly terminate the last line,
     // but only if there was output to be printed
-    if !out_lines.is_empty() {
-        out_lines.push("");
+    if !out.is_empty() {
+        out.push('\n');
     }
 
-    let out = out_lines.join("\n");
     let _bomb = Bomb(&out);
     match (output.status.success(), lang_string.compile_fail) {
         (true, true) => {