From 6b179e3a67a2242b63892a1831ba217d968c2f62 Mon Sep 17 00:00:00 2001
From: Aaron Kofsky <aaronko@umich.edu>
Date: Sat, 4 Jun 2022 13:50:12 -0400
Subject: [PATCH] Set `let_underscore_lock` to Deny by default.

Clippy sets this lint to Deny by default, and it having the lint be Deny
is useful for when we test the lint against a Crater run.
---
 compiler/rustc_lint/src/let_underscore.rs             | 4 ++--
 src/test/ui/let_underscore/let_underscore_lock.rs     | 4 +---
 src/test/ui/let_underscore/let_underscore_lock.stderr | 8 ++++----
 3 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/compiler/rustc_lint/src/let_underscore.rs b/compiler/rustc_lint/src/let_underscore.rs
index 4e4cedaeb7821..306c6197c24e2 100644
--- a/compiler/rustc_lint/src/let_underscore.rs
+++ b/compiler/rustc_lint/src/let_underscore.rs
@@ -55,7 +55,7 @@ declare_lint! {
     /// of at end of scope, which is typically incorrect.
     ///
     /// ### Example
-    /// ```rust
+    /// ```compile_fail
     /// use std::sync::{Arc, Mutex};
     /// use std::thread;
     /// let data = Arc::new(Mutex::new(0));
@@ -83,7 +83,7 @@ declare_lint! {
     /// calling `std::mem::drop` on the expression is clearer and helps convey
     /// intent.
     pub LET_UNDERSCORE_LOCK,
-    Warn,
+    Deny,
     "non-binding let on a synchronization lock"
 }
 
diff --git a/src/test/ui/let_underscore/let_underscore_lock.rs b/src/test/ui/let_underscore/let_underscore_lock.rs
index 774b610db2fb8..c37264136ef7f 100644
--- a/src/test/ui/let_underscore/let_underscore_lock.rs
+++ b/src/test/ui/let_underscore/let_underscore_lock.rs
@@ -1,8 +1,6 @@
-// run-pass
-
 use std::sync::{Arc, Mutex};
 
 fn main() {
     let data = Arc::new(Mutex::new(0));
-    let _ = data.lock().unwrap(); //~WARNING non-binding let on a synchronization lock
+    let _ = data.lock().unwrap(); //~ERROR non-binding let on a synchronization lock
 }
diff --git a/src/test/ui/let_underscore/let_underscore_lock.stderr b/src/test/ui/let_underscore/let_underscore_lock.stderr
index 08f81962f3c65..b7e14e8c7b5c5 100644
--- a/src/test/ui/let_underscore/let_underscore_lock.stderr
+++ b/src/test/ui/let_underscore/let_underscore_lock.stderr
@@ -1,10 +1,10 @@
-warning: non-binding let on a synchronization lock
-  --> $DIR/let_underscore_lock.rs:7:5
+error: non-binding let on a synchronization lock
+  --> $DIR/let_underscore_lock.rs:5:5
    |
 LL |     let _ = data.lock().unwrap();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: `#[warn(let_underscore_lock)]` on by default
+   = note: `#[deny(let_underscore_lock)]` on by default
 help: consider binding to an unused variable
    |
 LL |     let _unused = data.lock().unwrap();
@@ -14,5 +14,5 @@ help: consider explicitly droping with `std::mem::drop`
 LL |     let _ = drop(...);
    |             ~~~~~~~~~
 
-warning: 1 warning emitted
+error: aborting due to previous error