From 57bf80f77626b134faaf2cd95664403627fba0da Mon Sep 17 00:00:00 2001
From: Daniel Smith <daniel.smith@datadoghq.com>
Date: Thu, 10 Sep 2020 15:53:36 -0400
Subject: [PATCH 01/10] Add lint for holding RefCell Ref across an await

---
 clippy_lints/src/await_holding_refcell_ref.rs | 83 +++++++++++++++++++
 clippy_lints/src/lib.rs                       |  4 +
 clippy_lints/src/utils/paths.rs               |  2 +
 tests/ui/await_holding_refcell_ref.rs         | 71 ++++++++++++++++
 tests/ui/await_holding_refcell_ref.stderr     | 77 +++++++++++++++++
 5 files changed, 237 insertions(+)
 create mode 100644 clippy_lints/src/await_holding_refcell_ref.rs
 create mode 100644 tests/ui/await_holding_refcell_ref.rs
 create mode 100644 tests/ui/await_holding_refcell_ref.stderr

diff --git a/clippy_lints/src/await_holding_refcell_ref.rs b/clippy_lints/src/await_holding_refcell_ref.rs
new file mode 100644
index 000000000000..9a75911acbea
--- /dev/null
+++ b/clippy_lints/src/await_holding_refcell_ref.rs
@@ -0,0 +1,83 @@
+use crate::utils::{match_def_path, paths, span_lint_and_note};
+use rustc_hir::def_id::DefId;
+use rustc_hir::{AsyncGeneratorKind, Body, BodyId, GeneratorKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::GeneratorInteriorTypeCause;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::Span;
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for calls to await while holding a
+    /// `RefCell` `Ref` or `RefMut`.
+    ///
+    /// **Why is this bad?** `RefCell` refs only check for exclusive mutable access
+    /// at runtime. Holding onto a `RefCell` ref across an `await` suspension point
+    /// risks panics from a mutable ref shared while other refs are outstanding.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    ///
+    /// ```rust,ignore
+    /// use std::cell::RefCell;
+    ///
+    /// async fn foo(x: &RefCell<u32>) {
+    ///   let b = x.borrow_mut()();
+    ///   *ref += 1;
+    ///   bar.await;
+    /// }
+    /// ```
+    ///
+    /// Use instead:
+    /// ```rust,ignore
+    /// use std::cell::RefCell;
+    ///
+    /// async fn foo(x: &RefCell<u32>) {
+    ///   {
+    ///     let b = x.borrow_mut();
+    ///     *ref += 1;
+    ///   }
+    ///   bar.await;
+    /// }
+    /// ```
+    pub AWAIT_HOLDING_REFCELL_REF,
+    pedantic,
+    "Inside an async function, holding a RefCell ref while calling await"
+}
+
+declare_lint_pass!(AwaitHoldingRefCellRef => [AWAIT_HOLDING_REFCELL_REF]);
+
+impl LateLintPass<'_> for AwaitHoldingRefCellRef {
+    fn check_body(&mut self, cx: &LateContext<'_>, body: &'_ Body<'_>) {
+        use AsyncGeneratorKind::{Block, Closure, Fn};
+        if let Some(GeneratorKind::Async(Block | Closure | Fn)) = body.generator_kind {
+            let body_id = BodyId {
+                hir_id: body.value.hir_id,
+            };
+            let def_id = cx.tcx.hir().body_owner_def_id(body_id);
+            let typeck_results = cx.tcx.typeck(def_id);
+            check_interior_types(cx, &typeck_results.generator_interior_types, body.value.span);
+        }
+    }
+}
+
+fn check_interior_types(cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorTypeCause<'_>], span: Span) {
+    for ty_cause in ty_causes {
+        if let rustc_middle::ty::Adt(adt, _) = ty_cause.ty.kind() {
+            if is_refcell_ref(cx, adt.did) {
+                span_lint_and_note(
+                    cx,
+                    AWAIT_HOLDING_REFCELL_REF,
+                    ty_cause.span,
+                    "this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.",
+                    ty_cause.scope_span.or(Some(span)),
+                    "these are all the await points this ref is held through",
+                );
+            }
+        }
+    }
+}
+
+fn is_refcell_ref(cx: &LateContext<'_>, def_id: DefId) -> bool {
+    match_def_path(cx, def_id, &paths::REFCELL_REF) || match_def_path(cx, def_id, &paths::REFCELL_REFMUT)
+}
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index d4d2f92a6a69..697199861047 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -161,6 +161,7 @@ mod async_yields_async;
 mod atomic_ordering;
 mod attrs;
 mod await_holding_lock;
+mod await_holding_refcell_ref;
 mod bit_mask;
 mod blacklisted_name;
 mod blocks_in_if_conditions;
@@ -510,6 +511,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &attrs::UNKNOWN_CLIPPY_LINTS,
         &attrs::USELESS_ATTRIBUTE,
         &await_holding_lock::AWAIT_HOLDING_LOCK,
+        &await_holding_refcell_ref::AWAIT_HOLDING_REFCELL_REF,
         &bit_mask::BAD_BIT_MASK,
         &bit_mask::INEFFECTIVE_BIT_MASK,
         &bit_mask::VERBOSE_BIT_MASK,
@@ -906,6 +908,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     // end register lints, do not remove this comment, it’s used in `update_lints`
 
     store.register_late_pass(|| box await_holding_lock::AwaitHoldingLock);
+    store.register_late_pass(|| box await_holding_refcell_ref::AwaitHoldingRefCellRef);
     store.register_late_pass(|| box serde_api::SerdeAPI);
     store.register_late_pass(|| box utils::internal_lints::CompilerLintFunctions::new());
     store.register_late_pass(|| box utils::internal_lints::LintWithoutLintPass::default());
@@ -1189,6 +1192,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_group(true, "clippy::pedantic", Some("clippy_pedantic"), vec![
         LintId::of(&attrs::INLINE_ALWAYS),
         LintId::of(&await_holding_lock::AWAIT_HOLDING_LOCK),
+        LintId::of(&await_holding_refcell_ref::AWAIT_HOLDING_REFCELL_REF),
         LintId::of(&bit_mask::VERBOSE_BIT_MASK),
         LintId::of(&checked_conversions::CHECKED_CONVERSIONS),
         LintId::of(&copies::MATCH_SAME_ARMS),
diff --git a/clippy_lints/src/utils/paths.rs b/clippy_lints/src/utils/paths.rs
index 5e769c690a69..cd9b92efe583 100644
--- a/clippy_lints/src/utils/paths.rs
+++ b/clippy_lints/src/utils/paths.rs
@@ -93,6 +93,8 @@ pub const RANGE_ARGUMENT_TRAIT: [&str; 3] = ["core", "ops", "RangeBounds"];
 pub const RC: [&str; 3] = ["alloc", "rc", "Rc"];
 pub const RC_PTR_EQ: [&str; 4] = ["alloc", "rc", "Rc", "ptr_eq"];
 pub const RECEIVER: [&str; 4] = ["std", "sync", "mpsc", "Receiver"];
+pub const REFCELL_REF: [&str; 3] = ["core", "cell", "Ref"];
+pub const REFCELL_REFMUT: [&str; 3] = ["core", "cell", "RefMut"];
 pub const REGEX_BUILDER_NEW: [&str; 5] = ["regex", "re_builder", "unicode", "RegexBuilder", "new"];
 pub const REGEX_BYTES_BUILDER_NEW: [&str; 5] = ["regex", "re_builder", "bytes", "RegexBuilder", "new"];
 pub const REGEX_BYTES_NEW: [&str; 4] = ["regex", "re_bytes", "Regex", "new"];
diff --git a/tests/ui/await_holding_refcell_ref.rs b/tests/ui/await_holding_refcell_ref.rs
new file mode 100644
index 000000000000..6e330f47dfc2
--- /dev/null
+++ b/tests/ui/await_holding_refcell_ref.rs
@@ -0,0 +1,71 @@
+// edition:2018
+#![warn(clippy::await_holding_refcell_ref)]
+
+use std::cell::RefCell;
+
+async fn bad(x: &RefCell<u32>) -> u32 {
+    let b = x.borrow();
+    baz().await
+}
+
+async fn bad_mut(x: &RefCell<u32>) -> u32 {
+    let b = x.borrow_mut();
+    baz().await
+}
+
+async fn good(x: &RefCell<u32>) -> u32 {
+    {
+        let b = x.borrow_mut();
+        let y = *b + 1;
+    }
+    baz().await;
+    let b = x.borrow_mut();
+    47
+}
+
+async fn baz() -> u32 {
+    42
+}
+
+async fn also_bad(x: &RefCell<u32>) -> u32 {
+    let first = baz().await;
+
+    let b = x.borrow_mut();
+
+    let second = baz().await;
+
+    let third = baz().await;
+
+    first + second + third
+}
+
+async fn not_good(x: &RefCell<u32>) -> u32 {
+    let first = baz().await;
+
+    let second = {
+        let b = x.borrow_mut();
+        baz().await
+    };
+
+    let third = baz().await;
+
+    first + second + third
+}
+
+#[allow(clippy::manual_async_fn)]
+fn block_bad(x: &RefCell<u32>) -> impl std::future::Future<Output = u32> + '_ {
+    async move {
+        let b = x.borrow_mut();
+        baz().await
+    }
+}
+
+fn main() {
+    let m = RefCell::new(100);
+    good(&m);
+    bad(&m);
+    bad_mut(&m);    
+    also_bad(&m);
+    not_good(&m);
+    block_bad(&m);
+}
diff --git a/tests/ui/await_holding_refcell_ref.stderr b/tests/ui/await_holding_refcell_ref.stderr
new file mode 100644
index 000000000000..b114945504a2
--- /dev/null
+++ b/tests/ui/await_holding_refcell_ref.stderr
@@ -0,0 +1,77 @@
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_refcell_ref.rs:7:9
+   |
+LL |     let b = x.borrow();
+   |         ^
+   |
+   = note: `-D clippy::await-holding-refcell-ref` implied by `-D warnings`
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_refcell_ref.rs:7:5
+   |
+LL | /     let b = x.borrow();
+LL | |     baz().await
+LL | | }
+   | |_^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_refcell_ref.rs:12:9
+   |
+LL |     let b = x.borrow_mut();
+   |         ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_refcell_ref.rs:12:5
+   |
+LL | /     let b = x.borrow_mut();
+LL | |     baz().await
+LL | | }
+   | |_^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_refcell_ref.rs:33:9
+   |
+LL |     let b = x.borrow_mut();
+   |         ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_refcell_ref.rs:33:5
+   |
+LL | /     let b = x.borrow_mut();
+LL | |
+LL | |     let second = baz().await;
+LL | |
+...  |
+LL | |     first + second + third
+LL | | }
+   | |_^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_refcell_ref.rs:46:13
+   |
+LL |         let b = x.borrow_mut();
+   |             ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_refcell_ref.rs:46:9
+   |
+LL | /         let b = x.borrow_mut();
+LL | |         baz().await
+LL | |     };
+   | |_____^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_refcell_ref.rs:58:13
+   |
+LL |         let b = x.borrow_mut();
+   |             ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_refcell_ref.rs:58:9
+   |
+LL | /         let b = x.borrow_mut();
+LL | |         baz().await
+LL | |     }
+   | |_____^
+
+error: aborting due to 5 previous errors
+

From 8727169f7243c87e3708d99e9602562370f01a1a Mon Sep 17 00:00:00 2001
From: Daniel Smith <daniel.smith@datadoghq.com>
Date: Thu, 10 Sep 2020 16:01:27 -0400
Subject: [PATCH 02/10] fmt

---
 tests/ui/await_holding_refcell_ref.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/ui/await_holding_refcell_ref.rs b/tests/ui/await_holding_refcell_ref.rs
index 6e330f47dfc2..8e30da85d141 100644
--- a/tests/ui/await_holding_refcell_ref.rs
+++ b/tests/ui/await_holding_refcell_ref.rs
@@ -64,7 +64,7 @@ fn main() {
     let m = RefCell::new(100);
     good(&m);
     bad(&m);
-    bad_mut(&m);    
+    bad_mut(&m);
     also_bad(&m);
     not_good(&m);
     block_bad(&m);

From 070a751d4cf350a71901f75bc99ca0e0922a3133 Mon Sep 17 00:00:00 2001
From: Daniel Smith <daniel.smith@datadoghq.com>
Date: Thu, 10 Sep 2020 16:02:00 -0400
Subject: [PATCH 03/10] update_lints

---
 CHANGELOG.md        | 1 +
 src/lintlist/mod.rs | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d82f970b8bf2..287301772e28 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1632,6 +1632,7 @@ Released 2018-09-13
 [`assign_ops`]: https://rust-lang.github.io/rust-clippy/master/index.html#assign_ops
 [`async_yields_async`]: https://rust-lang.github.io/rust-clippy/master/index.html#async_yields_async
 [`await_holding_lock`]: https://rust-lang.github.io/rust-clippy/master/index.html#await_holding_lock
+[`await_holding_refcell_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#await_holding_refcell_ref
 [`bad_bit_mask`]: https://rust-lang.github.io/rust-clippy/master/index.html#bad_bit_mask
 [`bind_instead_of_map`]: https://rust-lang.github.io/rust-clippy/master/index.html#bind_instead_of_map
 [`blacklisted_name`]: https://rust-lang.github.io/rust-clippy/master/index.html#blacklisted_name
diff --git a/src/lintlist/mod.rs b/src/lintlist/mod.rs
index 6301d623a2b1..21185a08d5c3 100644
--- a/src/lintlist/mod.rs
+++ b/src/lintlist/mod.rs
@@ -67,6 +67,13 @@ vec![
         deprecation: None,
         module: "await_holding_lock",
     },
+    Lint {
+        name: "await_holding_refcell_ref",
+        group: "pedantic",
+        desc: "Inside an async function, holding a RefCell ref while calling await",
+        deprecation: None,
+        module: "await_holding_refcell_ref",
+    },
     Lint {
         name: "bad_bit_mask",
         group: "correctness",

From 0f4abbf99a6f1ed783ea6935c83427c2aef95144 Mon Sep 17 00:00:00 2001
From: Daniel Smith <daniel.smith@datadoghq.com>
Date: Mon, 28 Sep 2020 12:57:18 -0400
Subject: [PATCH 04/10] Better naming post copy/paste

---
 tests/ui/await_holding_refcell_ref.rs | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/tests/ui/await_holding_refcell_ref.rs b/tests/ui/await_holding_refcell_ref.rs
index 8e30da85d141..dd3adc494f1b 100644
--- a/tests/ui/await_holding_refcell_ref.rs
+++ b/tests/ui/await_holding_refcell_ref.rs
@@ -61,11 +61,11 @@ fn block_bad(x: &RefCell<u32>) -> impl std::future::Future<Output = u32> + '_ {
 }
 
 fn main() {
-    let m = RefCell::new(100);
-    good(&m);
-    bad(&m);
-    bad_mut(&m);
-    also_bad(&m);
-    not_good(&m);
-    block_bad(&m);
+    let rc = RefCell::new(100);
+    good(&rc);
+    bad(&rc);
+    bad_mut(&rc);
+    also_bad(&rc);
+    not_good(&rc);
+    block_bad(&rc);
 }

From b3a427d8733a549b11f9bc88eceb31c857851411 Mon Sep 17 00:00:00 2001
From: Daniel Smith <daniel.smith@datadoghq.com>
Date: Mon, 28 Sep 2020 13:29:37 -0400
Subject: [PATCH 05/10] Add another test case

---
 tests/ui/await_holding_refcell_ref.rs     | 15 ++++++++++++
 tests/ui/await_holding_refcell_ref.stderr | 28 +++++++++++++++++++----
 2 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/tests/ui/await_holding_refcell_ref.rs b/tests/ui/await_holding_refcell_ref.rs
index dd3adc494f1b..88841597bb60 100644
--- a/tests/ui/await_holding_refcell_ref.rs
+++ b/tests/ui/await_holding_refcell_ref.rs
@@ -39,6 +39,20 @@ async fn also_bad(x: &RefCell<u32>) -> u32 {
     first + second + third
 }
 
+async fn less_bad(x: &RefCell<u32>) -> u32 {
+    let first = baz().await;
+
+    let b = x.borrow_mut();
+
+    let second = baz().await;
+
+    drop(b);
+
+    let third = baz().await;
+
+    first + second + third
+}
+
 async fn not_good(x: &RefCell<u32>) -> u32 {
     let first = baz().await;
 
@@ -66,6 +80,7 @@ fn main() {
     bad(&rc);
     bad_mut(&rc);
     also_bad(&rc);
+    less_bad(&rc);
     not_good(&rc);
     block_bad(&rc);
 }
diff --git a/tests/ui/await_holding_refcell_ref.stderr b/tests/ui/await_holding_refcell_ref.stderr
index b114945504a2..b504f0454913 100644
--- a/tests/ui/await_holding_refcell_ref.stderr
+++ b/tests/ui/await_holding_refcell_ref.stderr
@@ -46,13 +46,31 @@ LL | | }
    | |_^
 
 error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
-  --> $DIR/await_holding_refcell_ref.rs:46:13
+  --> $DIR/await_holding_refcell_ref.rs:45:9
+   |
+LL |     let b = x.borrow_mut();
+   |         ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_refcell_ref.rs:45:5
+   |
+LL | /     let b = x.borrow_mut();
+LL | |
+LL | |     let second = baz().await;
+LL | |
+...  |
+LL | |     first + second + third
+LL | | }
+   | |_^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_refcell_ref.rs:60:13
    |
 LL |         let b = x.borrow_mut();
    |             ^
    |
 note: these are all the await points this ref is held through
-  --> $DIR/await_holding_refcell_ref.rs:46:9
+  --> $DIR/await_holding_refcell_ref.rs:60:9
    |
 LL | /         let b = x.borrow_mut();
 LL | |         baz().await
@@ -60,18 +78,18 @@ LL | |     };
    | |_____^
 
 error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
-  --> $DIR/await_holding_refcell_ref.rs:58:13
+  --> $DIR/await_holding_refcell_ref.rs:72:13
    |
 LL |         let b = x.borrow_mut();
    |             ^
    |
 note: these are all the await points this ref is held through
-  --> $DIR/await_holding_refcell_ref.rs:58:9
+  --> $DIR/await_holding_refcell_ref.rs:72:9
    |
 LL | /         let b = x.borrow_mut();
 LL | |         baz().await
 LL | |     }
    | |_____^
 
-error: aborting due to 5 previous errors
+error: aborting due to 6 previous errors
 

From 3ed69cdb13e5953467f9d849d7ad480479ca01d6 Mon Sep 17 00:00:00 2001
From: Daniel Smith <daniel.smith@datadoghq.com>
Date: Tue, 13 Oct 2020 12:39:20 -0400
Subject: [PATCH 06/10] Move existing lint into shared file

---
 ..._holding_lock.rs => await_holding_invalid.rs} |  0
 clippy_lints/src/lib.rs                          |  8 ++++----
 src/lintlist/mod.rs                              |  2 +-
 ..._holding_lock.rs => await_holding_invalid.rs} |  0
 ..._lock.stderr => await_holding_invalid.stderr} | 16 ++++++++--------
 5 files changed, 13 insertions(+), 13 deletions(-)
 rename clippy_lints/src/{await_holding_lock.rs => await_holding_invalid.rs} (100%)
 rename tests/ui/{await_holding_lock.rs => await_holding_invalid.rs} (100%)
 rename tests/ui/{await_holding_lock.stderr => await_holding_invalid.stderr} (84%)

diff --git a/clippy_lints/src/await_holding_lock.rs b/clippy_lints/src/await_holding_invalid.rs
similarity index 100%
rename from clippy_lints/src/await_holding_lock.rs
rename to clippy_lints/src/await_holding_invalid.rs
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 697199861047..47cc0c903229 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -160,7 +160,7 @@ mod assign_ops;
 mod async_yields_async;
 mod atomic_ordering;
 mod attrs;
-mod await_holding_lock;
+mod await_holding_invalid;
 mod await_holding_refcell_ref;
 mod bit_mask;
 mod blacklisted_name;
@@ -510,7 +510,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &attrs::MISMATCHED_TARGET_OS,
         &attrs::UNKNOWN_CLIPPY_LINTS,
         &attrs::USELESS_ATTRIBUTE,
-        &await_holding_lock::AWAIT_HOLDING_LOCK,
+        &await_holding_invalid::AWAIT_HOLDING_LOCK,
         &await_holding_refcell_ref::AWAIT_HOLDING_REFCELL_REF,
         &bit_mask::BAD_BIT_MASK,
         &bit_mask::INEFFECTIVE_BIT_MASK,
@@ -907,7 +907,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     ]);
     // end register lints, do not remove this comment, it’s used in `update_lints`
 
-    store.register_late_pass(|| box await_holding_lock::AwaitHoldingLock);
+    store.register_late_pass(|| box await_holding_invalid::AwaitHoldingLock);
     store.register_late_pass(|| box await_holding_refcell_ref::AwaitHoldingRefCellRef);
     store.register_late_pass(|| box serde_api::SerdeAPI);
     store.register_late_pass(|| box utils::internal_lints::CompilerLintFunctions::new());
@@ -1191,7 +1191,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
 
     store.register_group(true, "clippy::pedantic", Some("clippy_pedantic"), vec![
         LintId::of(&attrs::INLINE_ALWAYS),
-        LintId::of(&await_holding_lock::AWAIT_HOLDING_LOCK),
+        LintId::of(&await_holding_invalid::AWAIT_HOLDING_LOCK),
         LintId::of(&await_holding_refcell_ref::AWAIT_HOLDING_REFCELL_REF),
         LintId::of(&bit_mask::VERBOSE_BIT_MASK),
         LintId::of(&checked_conversions::CHECKED_CONVERSIONS),
diff --git a/src/lintlist/mod.rs b/src/lintlist/mod.rs
index 21185a08d5c3..63e9220ccd50 100644
--- a/src/lintlist/mod.rs
+++ b/src/lintlist/mod.rs
@@ -65,7 +65,7 @@ vec![
         group: "pedantic",
         desc: "Inside an async function, holding a MutexGuard while calling await",
         deprecation: None,
-        module: "await_holding_lock",
+        module: "await_holding_invalid",
     },
     Lint {
         name: "await_holding_refcell_ref",
diff --git a/tests/ui/await_holding_lock.rs b/tests/ui/await_holding_invalid.rs
similarity index 100%
rename from tests/ui/await_holding_lock.rs
rename to tests/ui/await_holding_invalid.rs
diff --git a/tests/ui/await_holding_lock.stderr b/tests/ui/await_holding_invalid.stderr
similarity index 84%
rename from tests/ui/await_holding_lock.stderr
rename to tests/ui/await_holding_invalid.stderr
index 21bf49d16f04..315d5731b962 100644
--- a/tests/ui/await_holding_lock.stderr
+++ b/tests/ui/await_holding_invalid.stderr
@@ -1,12 +1,12 @@
 error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
-  --> $DIR/await_holding_lock.rs:7:9
+  --> $DIR/await_holding_invalid.rs:7:9
    |
 LL |     let guard = x.lock().unwrap();
    |         ^^^^^
    |
    = note: `-D clippy::await-holding-lock` implied by `-D warnings`
 note: these are all the await points this lock is held through
-  --> $DIR/await_holding_lock.rs:7:5
+  --> $DIR/await_holding_invalid.rs:7:5
    |
 LL | /     let guard = x.lock().unwrap();
 LL | |     baz().await
@@ -14,13 +14,13 @@ LL | | }
    | |_^
 
 error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
-  --> $DIR/await_holding_lock.rs:28:9
+  --> $DIR/await_holding_invalid.rs:28:9
    |
 LL |     let guard = x.lock().unwrap();
    |         ^^^^^
    |
 note: these are all the await points this lock is held through
-  --> $DIR/await_holding_lock.rs:28:5
+  --> $DIR/await_holding_invalid.rs:28:5
    |
 LL | /     let guard = x.lock().unwrap();
 LL | |
@@ -32,13 +32,13 @@ LL | | }
    | |_^
 
 error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
-  --> $DIR/await_holding_lock.rs:41:13
+  --> $DIR/await_holding_invalid.rs:41:13
    |
 LL |         let guard = x.lock().unwrap();
    |             ^^^^^
    |
 note: these are all the await points this lock is held through
-  --> $DIR/await_holding_lock.rs:41:9
+  --> $DIR/await_holding_invalid.rs:41:9
    |
 LL | /         let guard = x.lock().unwrap();
 LL | |         baz().await
@@ -46,13 +46,13 @@ LL | |     };
    | |_____^
 
 error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
-  --> $DIR/await_holding_lock.rs:53:13
+  --> $DIR/await_holding_invalid.rs:53:13
    |
 LL |         let guard = x.lock().unwrap();
    |             ^^^^^
    |
 note: these are all the await points this lock is held through
-  --> $DIR/await_holding_lock.rs:53:9
+  --> $DIR/await_holding_invalid.rs:53:9
    |
 LL | /         let guard = x.lock().unwrap();
 LL | |         baz().await

From ee20ebadafc9b2e4995015097e376c0a866d84af Mon Sep 17 00:00:00 2001
From: Daniel Smith <daniel.smith@datadoghq.com>
Date: Tue, 13 Oct 2020 13:15:45 -0400
Subject: [PATCH 07/10] Move refcell lint into shared module

---
 clippy_lints/src/await_holding_invalid.rs     |  80 ++++++++++++-
 clippy_lints/src/await_holding_refcell_ref.rs |  83 -------------
 clippy_lints/src/lib.rs                       |   7 +-
 src/lintlist/mod.rs                           |   2 +-
 tests/ui/await_holding_invalid.rs             | 104 ++++++++++++++--
 tests/ui/await_holding_invalid.stderr         | 111 ++++++++++++++++--
 tests/ui/await_holding_refcell_ref.rs         |  86 --------------
 tests/ui/await_holding_refcell_ref.stderr     |  95 ---------------
 8 files changed, 276 insertions(+), 292 deletions(-)
 delete mode 100644 clippy_lints/src/await_holding_refcell_ref.rs
 delete mode 100644 tests/ui/await_holding_refcell_ref.rs
 delete mode 100644 tests/ui/await_holding_refcell_ref.stderr

diff --git a/clippy_lints/src/await_holding_invalid.rs b/clippy_lints/src/await_holding_invalid.rs
index 367534499fd0..2000bdae363f 100644
--- a/clippy_lints/src/await_holding_invalid.rs
+++ b/clippy_lints/src/await_holding_invalid.rs
@@ -60,12 +60,12 @@ impl LateLintPass<'_> for AwaitHoldingLock {
             };
             let def_id = cx.tcx.hir().body_owner_def_id(body_id);
             let typeck_results = cx.tcx.typeck(def_id);
-            check_interior_types(cx, &typeck_results.generator_interior_types, body.value.span);
+            check_interior_types_lock(cx, &typeck_results.generator_interior_types, body.value.span);
         }
     }
 }
 
-fn check_interior_types(cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorTypeCause<'_>], span: Span) {
+fn check_interior_types_lock(cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorTypeCause<'_>], span: Span) {
     for ty_cause in ty_causes {
         if let rustc_middle::ty::Adt(adt, _) = ty_cause.ty.kind() {
             if is_mutex_guard(cx, adt.did) {
@@ -90,3 +90,79 @@ fn is_mutex_guard(cx: &LateContext<'_>, def_id: DefId) -> bool {
         || match_def_path(cx, def_id, &paths::PARKING_LOT_RWLOCK_READ_GUARD)
         || match_def_path(cx, def_id, &paths::PARKING_LOT_RWLOCK_WRITE_GUARD)
 }
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for calls to await while holding a
+    /// `RefCell` `Ref` or `RefMut`.
+    ///
+    /// **Why is this bad?** `RefCell` refs only check for exclusive mutable access
+    /// at runtime. Holding onto a `RefCell` ref across an `await` suspension point
+    /// risks panics from a mutable ref shared while other refs are outstanding.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    ///
+    /// ```rust,ignore
+    /// use std::cell::RefCell;
+    ///
+    /// async fn foo(x: &RefCell<u32>) {
+    ///   let b = x.borrow_mut()();
+    ///   *ref += 1;
+    ///   bar.await;
+    /// }
+    /// ```
+    ///
+    /// Use instead:
+    /// ```rust,ignore
+    /// use std::cell::RefCell;
+    ///
+    /// async fn foo(x: &RefCell<u32>) {
+    ///   {
+    ///     let b = x.borrow_mut();
+    ///     *ref += 1;
+    ///   }
+    ///   bar.await;
+    /// }
+    /// ```
+    pub AWAIT_HOLDING_REFCELL_REF,
+    pedantic,
+    "Inside an async function, holding a RefCell ref while calling await"
+}
+
+declare_lint_pass!(AwaitHoldingRefCellRef => [AWAIT_HOLDING_REFCELL_REF]);
+
+impl LateLintPass<'_> for AwaitHoldingRefCellRef {
+    fn check_body(&mut self, cx: &LateContext<'_>, body: &'_ Body<'_>) {
+        use AsyncGeneratorKind::{Block, Closure, Fn};
+        if let Some(GeneratorKind::Async(Block | Closure | Fn)) = body.generator_kind {
+            let body_id = BodyId {
+                hir_id: body.value.hir_id,
+            };
+            let def_id = cx.tcx.hir().body_owner_def_id(body_id);
+            let typeck_results = cx.tcx.typeck(def_id);
+            check_interior_types_refcell(cx, &typeck_results.generator_interior_types, body.value.span);
+        }
+    }
+}
+
+fn check_interior_types_refcell(cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorTypeCause<'_>], span: Span) {
+    for ty_cause in ty_causes {
+        if let rustc_middle::ty::Adt(adt, _) = ty_cause.ty.kind() {
+            if is_refcell_ref(cx, adt.did) {
+                span_lint_and_note(
+                        cx,
+                        AWAIT_HOLDING_REFCELL_REF,
+                        ty_cause.span,
+                        "this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.",
+                        ty_cause.scope_span.or(Some(span)),
+                        "these are all the await points this ref is held through",
+                    );
+            }
+        }
+    }
+}
+
+fn is_refcell_ref(cx: &LateContext<'_>, def_id: DefId) -> bool {
+    match_def_path(cx, def_id, &paths::REFCELL_REF) || match_def_path(cx, def_id, &paths::REFCELL_REFMUT)
+}
diff --git a/clippy_lints/src/await_holding_refcell_ref.rs b/clippy_lints/src/await_holding_refcell_ref.rs
deleted file mode 100644
index 9a75911acbea..000000000000
--- a/clippy_lints/src/await_holding_refcell_ref.rs
+++ /dev/null
@@ -1,83 +0,0 @@
-use crate::utils::{match_def_path, paths, span_lint_and_note};
-use rustc_hir::def_id::DefId;
-use rustc_hir::{AsyncGeneratorKind, Body, BodyId, GeneratorKind};
-use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty::GeneratorInteriorTypeCause;
-use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::Span;
-
-declare_clippy_lint! {
-    /// **What it does:** Checks for calls to await while holding a
-    /// `RefCell` `Ref` or `RefMut`.
-    ///
-    /// **Why is this bad?** `RefCell` refs only check for exclusive mutable access
-    /// at runtime. Holding onto a `RefCell` ref across an `await` suspension point
-    /// risks panics from a mutable ref shared while other refs are outstanding.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    ///
-    /// ```rust,ignore
-    /// use std::cell::RefCell;
-    ///
-    /// async fn foo(x: &RefCell<u32>) {
-    ///   let b = x.borrow_mut()();
-    ///   *ref += 1;
-    ///   bar.await;
-    /// }
-    /// ```
-    ///
-    /// Use instead:
-    /// ```rust,ignore
-    /// use std::cell::RefCell;
-    ///
-    /// async fn foo(x: &RefCell<u32>) {
-    ///   {
-    ///     let b = x.borrow_mut();
-    ///     *ref += 1;
-    ///   }
-    ///   bar.await;
-    /// }
-    /// ```
-    pub AWAIT_HOLDING_REFCELL_REF,
-    pedantic,
-    "Inside an async function, holding a RefCell ref while calling await"
-}
-
-declare_lint_pass!(AwaitHoldingRefCellRef => [AWAIT_HOLDING_REFCELL_REF]);
-
-impl LateLintPass<'_> for AwaitHoldingRefCellRef {
-    fn check_body(&mut self, cx: &LateContext<'_>, body: &'_ Body<'_>) {
-        use AsyncGeneratorKind::{Block, Closure, Fn};
-        if let Some(GeneratorKind::Async(Block | Closure | Fn)) = body.generator_kind {
-            let body_id = BodyId {
-                hir_id: body.value.hir_id,
-            };
-            let def_id = cx.tcx.hir().body_owner_def_id(body_id);
-            let typeck_results = cx.tcx.typeck(def_id);
-            check_interior_types(cx, &typeck_results.generator_interior_types, body.value.span);
-        }
-    }
-}
-
-fn check_interior_types(cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorTypeCause<'_>], span: Span) {
-    for ty_cause in ty_causes {
-        if let rustc_middle::ty::Adt(adt, _) = ty_cause.ty.kind() {
-            if is_refcell_ref(cx, adt.did) {
-                span_lint_and_note(
-                    cx,
-                    AWAIT_HOLDING_REFCELL_REF,
-                    ty_cause.span,
-                    "this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.",
-                    ty_cause.scope_span.or(Some(span)),
-                    "these are all the await points this ref is held through",
-                );
-            }
-        }
-    }
-}
-
-fn is_refcell_ref(cx: &LateContext<'_>, def_id: DefId) -> bool {
-    match_def_path(cx, def_id, &paths::REFCELL_REF) || match_def_path(cx, def_id, &paths::REFCELL_REFMUT)
-}
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 47cc0c903229..0c5baf96970c 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -161,7 +161,6 @@ mod async_yields_async;
 mod atomic_ordering;
 mod attrs;
 mod await_holding_invalid;
-mod await_holding_refcell_ref;
 mod bit_mask;
 mod blacklisted_name;
 mod blocks_in_if_conditions;
@@ -511,7 +510,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &attrs::UNKNOWN_CLIPPY_LINTS,
         &attrs::USELESS_ATTRIBUTE,
         &await_holding_invalid::AWAIT_HOLDING_LOCK,
-        &await_holding_refcell_ref::AWAIT_HOLDING_REFCELL_REF,
+        &await_holding_invalid::AWAIT_HOLDING_REFCELL_REF,
         &bit_mask::BAD_BIT_MASK,
         &bit_mask::INEFFECTIVE_BIT_MASK,
         &bit_mask::VERBOSE_BIT_MASK,
@@ -908,7 +907,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     // end register lints, do not remove this comment, it’s used in `update_lints`
 
     store.register_late_pass(|| box await_holding_invalid::AwaitHoldingLock);
-    store.register_late_pass(|| box await_holding_refcell_ref::AwaitHoldingRefCellRef);
+    store.register_late_pass(|| box await_holding_invalid::AwaitHoldingRefCellRef);
     store.register_late_pass(|| box serde_api::SerdeAPI);
     store.register_late_pass(|| box utils::internal_lints::CompilerLintFunctions::new());
     store.register_late_pass(|| box utils::internal_lints::LintWithoutLintPass::default());
@@ -1192,7 +1191,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_group(true, "clippy::pedantic", Some("clippy_pedantic"), vec![
         LintId::of(&attrs::INLINE_ALWAYS),
         LintId::of(&await_holding_invalid::AWAIT_HOLDING_LOCK),
-        LintId::of(&await_holding_refcell_ref::AWAIT_HOLDING_REFCELL_REF),
+        LintId::of(&await_holding_invalid::AWAIT_HOLDING_REFCELL_REF),
         LintId::of(&bit_mask::VERBOSE_BIT_MASK),
         LintId::of(&checked_conversions::CHECKED_CONVERSIONS),
         LintId::of(&copies::MATCH_SAME_ARMS),
diff --git a/src/lintlist/mod.rs b/src/lintlist/mod.rs
index 63e9220ccd50..c955f37b83a3 100644
--- a/src/lintlist/mod.rs
+++ b/src/lintlist/mod.rs
@@ -72,7 +72,7 @@ vec![
         group: "pedantic",
         desc: "Inside an async function, holding a RefCell ref while calling await",
         deprecation: None,
-        module: "await_holding_refcell_ref",
+        module: "await_holding_invalid",
     },
     Lint {
         name: "bad_bit_mask",
diff --git a/tests/ui/await_holding_invalid.rs b/tests/ui/await_holding_invalid.rs
index 0458950edee1..45aa3e64292e 100644
--- a/tests/ui/await_holding_invalid.rs
+++ b/tests/ui/await_holding_invalid.rs
@@ -1,14 +1,15 @@
 // edition:2018
-#![warn(clippy::await_holding_lock)]
+#![warn(clippy::await_holding_lock, clippy::await_holding_refcell_ref)]
 
+use std::cell::RefCell;
 use std::sync::Mutex;
 
-async fn bad(x: &Mutex<u32>) -> u32 {
+async fn bad_lock(x: &Mutex<u32>) -> u32 {
     let guard = x.lock().unwrap();
     baz().await
 }
 
-async fn good(x: &Mutex<u32>) -> u32 {
+async fn good_lock(x: &Mutex<u32>) -> u32 {
     {
         let guard = x.lock().unwrap();
         let y = *guard + 1;
@@ -22,7 +23,7 @@ async fn baz() -> u32 {
     42
 }
 
-async fn also_bad(x: &Mutex<u32>) -> u32 {
+async fn also_bad_lock(x: &Mutex<u32>) -> u32 {
     let first = baz().await;
 
     let guard = x.lock().unwrap();
@@ -34,7 +35,7 @@ async fn also_bad(x: &Mutex<u32>) -> u32 {
     first + second + third
 }
 
-async fn not_good(x: &Mutex<u32>) -> u32 {
+async fn not_good_lock(x: &Mutex<u32>) -> u32 {
     let first = baz().await;
 
     let second = {
@@ -48,18 +49,97 @@ async fn not_good(x: &Mutex<u32>) -> u32 {
 }
 
 #[allow(clippy::manual_async_fn)]
-fn block_bad(x: &Mutex<u32>) -> impl std::future::Future<Output = u32> + '_ {
+fn block_bad_lock(x: &Mutex<u32>) -> impl std::future::Future<Output = u32> + '_ {
     async move {
         let guard = x.lock().unwrap();
         baz().await
     }
 }
 
+async fn bad_refcell(x: &RefCell<u32>) -> u32 {
+    let b = x.borrow();
+    baz().await
+}
+
+async fn bad_mut_refcell(x: &RefCell<u32>) -> u32 {
+    let b = x.borrow_mut();
+    baz().await
+}
+
+async fn good_refcell(x: &RefCell<u32>) -> u32 {
+    {
+        let b = x.borrow_mut();
+        let y = *b + 1;
+    }
+    baz().await;
+    let b = x.borrow_mut();
+    47
+}
+
+async fn also_bad_refcell(x: &RefCell<u32>) -> u32 {
+    let first = baz().await;
+
+    let b = x.borrow_mut();
+
+    let second = baz().await;
+
+    let third = baz().await;
+
+    first + second + third
+}
+
+async fn less_bad_refcell(x: &RefCell<u32>) -> u32 {
+    let first = baz().await;
+
+    let b = x.borrow_mut();
+
+    let second = baz().await;
+
+    drop(b);
+
+    let third = baz().await;
+
+    first + second + third
+}
+
+async fn not_good_refcell(x: &RefCell<u32>) -> u32 {
+    let first = baz().await;
+
+    let second = {
+        let b = x.borrow_mut();
+        baz().await
+    };
+
+    let third = baz().await;
+
+    first + second + third
+}
+
+#[allow(clippy::manual_async_fn)]
+fn block_bad_refcell(x: &RefCell<u32>) -> impl std::future::Future<Output = u32> + '_ {
+    async move {
+        let b = x.borrow_mut();
+        baz().await
+    }
+}
+
 fn main() {
-    let m = Mutex::new(100);
-    good(&m);
-    bad(&m);
-    also_bad(&m);
-    not_good(&m);
-    block_bad(&m);
+    {
+        let m = Mutex::new(100);
+        good_lock(&m);
+        bad_lock(&m);
+        also_bad_lock(&m);
+        not_good_lock(&m);
+        block_bad_lock(&m);
+    }
+    {
+        let rc = RefCell::new(100);
+        good_refcell(&rc);
+        bad_refcell(&rc);
+        bad_mut_refcell(&rc);
+        also_bad_refcell(&rc);
+        less_bad_refcell(&rc);
+        not_good_refcell(&rc);
+        block_bad_refcell(&rc);
+    }
 }
diff --git a/tests/ui/await_holding_invalid.stderr b/tests/ui/await_holding_invalid.stderr
index 315d5731b962..c8d49820c020 100644
--- a/tests/ui/await_holding_invalid.stderr
+++ b/tests/ui/await_holding_invalid.stderr
@@ -1,12 +1,12 @@
 error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
-  --> $DIR/await_holding_invalid.rs:7:9
+  --> $DIR/await_holding_invalid.rs:8:9
    |
 LL |     let guard = x.lock().unwrap();
    |         ^^^^^
    |
    = note: `-D clippy::await-holding-lock` implied by `-D warnings`
 note: these are all the await points this lock is held through
-  --> $DIR/await_holding_invalid.rs:7:5
+  --> $DIR/await_holding_invalid.rs:8:5
    |
 LL | /     let guard = x.lock().unwrap();
 LL | |     baz().await
@@ -14,13 +14,13 @@ LL | | }
    | |_^
 
 error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
-  --> $DIR/await_holding_invalid.rs:28:9
+  --> $DIR/await_holding_invalid.rs:29:9
    |
 LL |     let guard = x.lock().unwrap();
    |         ^^^^^
    |
 note: these are all the await points this lock is held through
-  --> $DIR/await_holding_invalid.rs:28:5
+  --> $DIR/await_holding_invalid.rs:29:5
    |
 LL | /     let guard = x.lock().unwrap();
 LL | |
@@ -32,13 +32,13 @@ LL | | }
    | |_^
 
 error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
-  --> $DIR/await_holding_invalid.rs:41:13
+  --> $DIR/await_holding_invalid.rs:42:13
    |
 LL |         let guard = x.lock().unwrap();
    |             ^^^^^
    |
 note: these are all the await points this lock is held through
-  --> $DIR/await_holding_invalid.rs:41:9
+  --> $DIR/await_holding_invalid.rs:42:9
    |
 LL | /         let guard = x.lock().unwrap();
 LL | |         baz().await
@@ -46,18 +46,111 @@ LL | |     };
    | |_____^
 
 error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
-  --> $DIR/await_holding_invalid.rs:53:13
+  --> $DIR/await_holding_invalid.rs:54:13
    |
 LL |         let guard = x.lock().unwrap();
    |             ^^^^^
    |
 note: these are all the await points this lock is held through
-  --> $DIR/await_holding_invalid.rs:53:9
+  --> $DIR/await_holding_invalid.rs:54:9
    |
 LL | /         let guard = x.lock().unwrap();
 LL | |         baz().await
 LL | |     }
    | |_____^
 
-error: aborting due to 4 previous errors
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_invalid.rs:60:9
+   |
+LL |     let b = x.borrow();
+   |         ^
+   |
+   = note: `-D clippy::await-holding-refcell-ref` implied by `-D warnings`
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_invalid.rs:60:5
+   |
+LL | /     let b = x.borrow();
+LL | |     baz().await
+LL | | }
+   | |_^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_invalid.rs:65:9
+   |
+LL |     let b = x.borrow_mut();
+   |         ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_invalid.rs:65:5
+   |
+LL | /     let b = x.borrow_mut();
+LL | |     baz().await
+LL | | }
+   | |_^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_invalid.rs:82:9
+   |
+LL |     let b = x.borrow_mut();
+   |         ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_invalid.rs:82:5
+   |
+LL | /     let b = x.borrow_mut();
+LL | |
+LL | |     let second = baz().await;
+LL | |
+...  |
+LL | |     first + second + third
+LL | | }
+   | |_^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_invalid.rs:94:9
+   |
+LL |     let b = x.borrow_mut();
+   |         ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_invalid.rs:94:5
+   |
+LL | /     let b = x.borrow_mut();
+LL | |
+LL | |     let second = baz().await;
+LL | |
+...  |
+LL | |     first + second + third
+LL | | }
+   | |_^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_invalid.rs:109:13
+   |
+LL |         let b = x.borrow_mut();
+   |             ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_invalid.rs:109:9
+   |
+LL | /         let b = x.borrow_mut();
+LL | |         baz().await
+LL | |     };
+   | |_____^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_invalid.rs:121:13
+   |
+LL |         let b = x.borrow_mut();
+   |             ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_invalid.rs:121:9
+   |
+LL | /         let b = x.borrow_mut();
+LL | |         baz().await
+LL | |     }
+   | |_____^
+
+error: aborting due to 10 previous errors
 
diff --git a/tests/ui/await_holding_refcell_ref.rs b/tests/ui/await_holding_refcell_ref.rs
deleted file mode 100644
index 88841597bb60..000000000000
--- a/tests/ui/await_holding_refcell_ref.rs
+++ /dev/null
@@ -1,86 +0,0 @@
-// edition:2018
-#![warn(clippy::await_holding_refcell_ref)]
-
-use std::cell::RefCell;
-
-async fn bad(x: &RefCell<u32>) -> u32 {
-    let b = x.borrow();
-    baz().await
-}
-
-async fn bad_mut(x: &RefCell<u32>) -> u32 {
-    let b = x.borrow_mut();
-    baz().await
-}
-
-async fn good(x: &RefCell<u32>) -> u32 {
-    {
-        let b = x.borrow_mut();
-        let y = *b + 1;
-    }
-    baz().await;
-    let b = x.borrow_mut();
-    47
-}
-
-async fn baz() -> u32 {
-    42
-}
-
-async fn also_bad(x: &RefCell<u32>) -> u32 {
-    let first = baz().await;
-
-    let b = x.borrow_mut();
-
-    let second = baz().await;
-
-    let third = baz().await;
-
-    first + second + third
-}
-
-async fn less_bad(x: &RefCell<u32>) -> u32 {
-    let first = baz().await;
-
-    let b = x.borrow_mut();
-
-    let second = baz().await;
-
-    drop(b);
-
-    let third = baz().await;
-
-    first + second + third
-}
-
-async fn not_good(x: &RefCell<u32>) -> u32 {
-    let first = baz().await;
-
-    let second = {
-        let b = x.borrow_mut();
-        baz().await
-    };
-
-    let third = baz().await;
-
-    first + second + third
-}
-
-#[allow(clippy::manual_async_fn)]
-fn block_bad(x: &RefCell<u32>) -> impl std::future::Future<Output = u32> + '_ {
-    async move {
-        let b = x.borrow_mut();
-        baz().await
-    }
-}
-
-fn main() {
-    let rc = RefCell::new(100);
-    good(&rc);
-    bad(&rc);
-    bad_mut(&rc);
-    also_bad(&rc);
-    less_bad(&rc);
-    not_good(&rc);
-    block_bad(&rc);
-}
diff --git a/tests/ui/await_holding_refcell_ref.stderr b/tests/ui/await_holding_refcell_ref.stderr
deleted file mode 100644
index b504f0454913..000000000000
--- a/tests/ui/await_holding_refcell_ref.stderr
+++ /dev/null
@@ -1,95 +0,0 @@
-error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
-  --> $DIR/await_holding_refcell_ref.rs:7:9
-   |
-LL |     let b = x.borrow();
-   |         ^
-   |
-   = note: `-D clippy::await-holding-refcell-ref` implied by `-D warnings`
-note: these are all the await points this ref is held through
-  --> $DIR/await_holding_refcell_ref.rs:7:5
-   |
-LL | /     let b = x.borrow();
-LL | |     baz().await
-LL | | }
-   | |_^
-
-error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
-  --> $DIR/await_holding_refcell_ref.rs:12:9
-   |
-LL |     let b = x.borrow_mut();
-   |         ^
-   |
-note: these are all the await points this ref is held through
-  --> $DIR/await_holding_refcell_ref.rs:12:5
-   |
-LL | /     let b = x.borrow_mut();
-LL | |     baz().await
-LL | | }
-   | |_^
-
-error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
-  --> $DIR/await_holding_refcell_ref.rs:33:9
-   |
-LL |     let b = x.borrow_mut();
-   |         ^
-   |
-note: these are all the await points this ref is held through
-  --> $DIR/await_holding_refcell_ref.rs:33:5
-   |
-LL | /     let b = x.borrow_mut();
-LL | |
-LL | |     let second = baz().await;
-LL | |
-...  |
-LL | |     first + second + third
-LL | | }
-   | |_^
-
-error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
-  --> $DIR/await_holding_refcell_ref.rs:45:9
-   |
-LL |     let b = x.borrow_mut();
-   |         ^
-   |
-note: these are all the await points this ref is held through
-  --> $DIR/await_holding_refcell_ref.rs:45:5
-   |
-LL | /     let b = x.borrow_mut();
-LL | |
-LL | |     let second = baz().await;
-LL | |
-...  |
-LL | |     first + second + third
-LL | | }
-   | |_^
-
-error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
-  --> $DIR/await_holding_refcell_ref.rs:60:13
-   |
-LL |         let b = x.borrow_mut();
-   |             ^
-   |
-note: these are all the await points this ref is held through
-  --> $DIR/await_holding_refcell_ref.rs:60:9
-   |
-LL | /         let b = x.borrow_mut();
-LL | |         baz().await
-LL | |     };
-   | |_____^
-
-error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
-  --> $DIR/await_holding_refcell_ref.rs:72:13
-   |
-LL |         let b = x.borrow_mut();
-   |             ^
-   |
-note: these are all the await points this ref is held through
-  --> $DIR/await_holding_refcell_ref.rs:72:9
-   |
-LL | /         let b = x.borrow_mut();
-LL | |         baz().await
-LL | |     }
-   | |_____^
-
-error: aborting due to 6 previous errors
-

From d8c6bce4407b1c99ed961f75a093ffe767818069 Mon Sep 17 00:00:00 2001
From: Daniel Smith <daniel.smith@datadoghq.com>
Date: Tue, 13 Oct 2020 13:20:01 -0400
Subject: [PATCH 08/10] Convert the await holding lints to correctness

---
 clippy_lints/src/await_holding_invalid.rs | 4 ++--
 clippy_lints/src/lib.rs                   | 6 ++++--
 src/lintlist/mod.rs                       | 4 ++--
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/clippy_lints/src/await_holding_invalid.rs b/clippy_lints/src/await_holding_invalid.rs
index 2000bdae363f..1d201ff095b9 100644
--- a/clippy_lints/src/await_holding_invalid.rs
+++ b/clippy_lints/src/await_holding_invalid.rs
@@ -45,7 +45,7 @@ declare_clippy_lint! {
     /// }
     /// ```
     pub AWAIT_HOLDING_LOCK,
-    pedantic,
+    correctness,
     "Inside an async function, holding a MutexGuard while calling await"
 }
 
@@ -126,7 +126,7 @@ declare_clippy_lint! {
     /// }
     /// ```
     pub AWAIT_HOLDING_REFCELL_REF,
-    pedantic,
+    correctness,
     "Inside an async function, holding a RefCell ref while calling await"
 }
 
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 0c5baf96970c..c627df209763 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -1190,8 +1190,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
 
     store.register_group(true, "clippy::pedantic", Some("clippy_pedantic"), vec![
         LintId::of(&attrs::INLINE_ALWAYS),
-        LintId::of(&await_holding_invalid::AWAIT_HOLDING_LOCK),
-        LintId::of(&await_holding_invalid::AWAIT_HOLDING_REFCELL_REF),
         LintId::of(&bit_mask::VERBOSE_BIT_MASK),
         LintId::of(&checked_conversions::CHECKED_CONVERSIONS),
         LintId::of(&copies::MATCH_SAME_ARMS),
@@ -1290,6 +1288,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&attrs::MISMATCHED_TARGET_OS),
         LintId::of(&attrs::UNKNOWN_CLIPPY_LINTS),
         LintId::of(&attrs::USELESS_ATTRIBUTE),
+        LintId::of(&await_holding_invalid::AWAIT_HOLDING_LOCK),
+        LintId::of(&await_holding_invalid::AWAIT_HOLDING_REFCELL_REF),
         LintId::of(&bit_mask::BAD_BIT_MASK),
         LintId::of(&bit_mask::INEFFECTIVE_BIT_MASK),
         LintId::of(&blacklisted_name::BLACKLISTED_NAME),
@@ -1736,6 +1736,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&attrs::DEPRECATED_SEMVER),
         LintId::of(&attrs::MISMATCHED_TARGET_OS),
         LintId::of(&attrs::USELESS_ATTRIBUTE),
+        LintId::of(&await_holding_invalid::AWAIT_HOLDING_LOCK),
+        LintId::of(&await_holding_invalid::AWAIT_HOLDING_REFCELL_REF),
         LintId::of(&bit_mask::BAD_BIT_MASK),
         LintId::of(&bit_mask::INEFFECTIVE_BIT_MASK),
         LintId::of(&booleans::LOGIC_BUG),
diff --git a/src/lintlist/mod.rs b/src/lintlist/mod.rs
index c955f37b83a3..d9e019e2b611 100644
--- a/src/lintlist/mod.rs
+++ b/src/lintlist/mod.rs
@@ -62,14 +62,14 @@ vec![
     },
     Lint {
         name: "await_holding_lock",
-        group: "pedantic",
+        group: "correctness",
         desc: "Inside an async function, holding a MutexGuard while calling await",
         deprecation: None,
         module: "await_holding_invalid",
     },
     Lint {
         name: "await_holding_refcell_ref",
-        group: "pedantic",
+        group: "correctness",
         desc: "Inside an async function, holding a RefCell ref while calling await",
         deprecation: None,
         module: "await_holding_invalid",

From 86f2b29d2ff33862264e2e6dfdc7cc20ad054ad1 Mon Sep 17 00:00:00 2001
From: Daniel Smith <daniel.smith@datadoghq.com>
Date: Mon, 19 Oct 2020 12:06:43 -0400
Subject: [PATCH 09/10] Merge lints into one pass

---
 clippy_lints/src/await_holding_invalid.rs | 69 ++++++++---------------
 clippy_lints/src/lib.rs                   |  3 +-
 2 files changed, 24 insertions(+), 48 deletions(-)

diff --git a/clippy_lints/src/await_holding_invalid.rs b/clippy_lints/src/await_holding_invalid.rs
index 1d201ff095b9..fcebb54c6c21 100644
--- a/clippy_lints/src/await_holding_invalid.rs
+++ b/clippy_lints/src/await_holding_invalid.rs
@@ -49,48 +49,6 @@ declare_clippy_lint! {
     "Inside an async function, holding a MutexGuard while calling await"
 }
 
-declare_lint_pass!(AwaitHoldingLock => [AWAIT_HOLDING_LOCK]);
-
-impl LateLintPass<'_> for AwaitHoldingLock {
-    fn check_body(&mut self, cx: &LateContext<'_>, body: &'_ Body<'_>) {
-        use AsyncGeneratorKind::{Block, Closure, Fn};
-        if let Some(GeneratorKind::Async(Block | Closure | Fn)) = body.generator_kind {
-            let body_id = BodyId {
-                hir_id: body.value.hir_id,
-            };
-            let def_id = cx.tcx.hir().body_owner_def_id(body_id);
-            let typeck_results = cx.tcx.typeck(def_id);
-            check_interior_types_lock(cx, &typeck_results.generator_interior_types, body.value.span);
-        }
-    }
-}
-
-fn check_interior_types_lock(cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorTypeCause<'_>], span: Span) {
-    for ty_cause in ty_causes {
-        if let rustc_middle::ty::Adt(adt, _) = ty_cause.ty.kind() {
-            if is_mutex_guard(cx, adt.did) {
-                span_lint_and_note(
-                    cx,
-                    AWAIT_HOLDING_LOCK,
-                    ty_cause.span,
-                    "this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.",
-                    ty_cause.scope_span.or(Some(span)),
-                    "these are all the await points this lock is held through",
-                );
-            }
-        }
-    }
-}
-
-fn is_mutex_guard(cx: &LateContext<'_>, def_id: DefId) -> bool {
-    match_def_path(cx, def_id, &paths::MUTEX_GUARD)
-        || match_def_path(cx, def_id, &paths::RWLOCK_READ_GUARD)
-        || match_def_path(cx, def_id, &paths::RWLOCK_WRITE_GUARD)
-        || match_def_path(cx, def_id, &paths::PARKING_LOT_MUTEX_GUARD)
-        || match_def_path(cx, def_id, &paths::PARKING_LOT_RWLOCK_READ_GUARD)
-        || match_def_path(cx, def_id, &paths::PARKING_LOT_RWLOCK_WRITE_GUARD)
-}
-
 declare_clippy_lint! {
     /// **What it does:** Checks for calls to await while holding a
     /// `RefCell` `Ref` or `RefMut`.
@@ -130,9 +88,9 @@ declare_clippy_lint! {
     "Inside an async function, holding a RefCell ref while calling await"
 }
 
-declare_lint_pass!(AwaitHoldingRefCellRef => [AWAIT_HOLDING_REFCELL_REF]);
+declare_lint_pass!(AwaitHolding => [AWAIT_HOLDING_LOCK, AWAIT_HOLDING_REFCELL_REF]);
 
-impl LateLintPass<'_> for AwaitHoldingRefCellRef {
+impl LateLintPass<'_> for AwaitHolding {
     fn check_body(&mut self, cx: &LateContext<'_>, body: &'_ Body<'_>) {
         use AsyncGeneratorKind::{Block, Closure, Fn};
         if let Some(GeneratorKind::Async(Block | Closure | Fn)) = body.generator_kind {
@@ -141,14 +99,24 @@ impl LateLintPass<'_> for AwaitHoldingRefCellRef {
             };
             let def_id = cx.tcx.hir().body_owner_def_id(body_id);
             let typeck_results = cx.tcx.typeck(def_id);
-            check_interior_types_refcell(cx, &typeck_results.generator_interior_types, body.value.span);
+            check_interior_types(cx, &typeck_results.generator_interior_types, body.value.span);
         }
     }
 }
 
-fn check_interior_types_refcell(cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorTypeCause<'_>], span: Span) {
+fn check_interior_types(cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorTypeCause<'_>], span: Span) {
     for ty_cause in ty_causes {
         if let rustc_middle::ty::Adt(adt, _) = ty_cause.ty.kind() {
+            if is_mutex_guard(cx, adt.did) {
+                span_lint_and_note(
+                    cx,
+                    AWAIT_HOLDING_LOCK,
+                    ty_cause.span,
+                    "this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.",
+                    ty_cause.scope_span.or(Some(span)),
+                    "these are all the await points this lock is held through",
+                );
+            }
             if is_refcell_ref(cx, adt.did) {
                 span_lint_and_note(
                         cx,
@@ -163,6 +131,15 @@ fn check_interior_types_refcell(cx: &LateContext<'_>, ty_causes: &[GeneratorInte
     }
 }
 
+fn is_mutex_guard(cx: &LateContext<'_>, def_id: DefId) -> bool {
+    match_def_path(cx, def_id, &paths::MUTEX_GUARD)
+        || match_def_path(cx, def_id, &paths::RWLOCK_READ_GUARD)
+        || match_def_path(cx, def_id, &paths::RWLOCK_WRITE_GUARD)
+        || match_def_path(cx, def_id, &paths::PARKING_LOT_MUTEX_GUARD)
+        || match_def_path(cx, def_id, &paths::PARKING_LOT_RWLOCK_READ_GUARD)
+        || match_def_path(cx, def_id, &paths::PARKING_LOT_RWLOCK_WRITE_GUARD)
+}
+
 fn is_refcell_ref(cx: &LateContext<'_>, def_id: DefId) -> bool {
     match_def_path(cx, def_id, &paths::REFCELL_REF) || match_def_path(cx, def_id, &paths::REFCELL_REFMUT)
 }
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index c627df209763..6d00e313ce1b 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -906,8 +906,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     ]);
     // end register lints, do not remove this comment, it’s used in `update_lints`
 
-    store.register_late_pass(|| box await_holding_invalid::AwaitHoldingLock);
-    store.register_late_pass(|| box await_holding_invalid::AwaitHoldingRefCellRef);
+    store.register_late_pass(|| box await_holding_invalid::AwaitHolding);
     store.register_late_pass(|| box serde_api::SerdeAPI);
     store.register_late_pass(|| box utils::internal_lints::CompilerLintFunctions::new());
     store.register_late_pass(|| box utils::internal_lints::LintWithoutLintPass::default());

From 4d3322525d9b65ce4c6fc183bc1cd3cfc9477300 Mon Sep 17 00:00:00 2001
From: Daniel Smith <daniel.smith@datadoghq.com>
Date: Mon, 19 Oct 2020 12:07:04 -0400
Subject: [PATCH 10/10] Separate tests for each lint

---
 tests/ui/await_holding_invalid.rs         | 145 --------------------
 tests/ui/await_holding_invalid.stderr     | 156 ----------------------
 tests/ui/await_holding_lock.rs            |  65 +++++++++
 tests/ui/await_holding_lock.stderr        |  63 +++++++++
 tests/ui/await_holding_refcell_ref.rs     |  86 ++++++++++++
 tests/ui/await_holding_refcell_ref.stderr |  95 +++++++++++++
 6 files changed, 309 insertions(+), 301 deletions(-)
 delete mode 100644 tests/ui/await_holding_invalid.rs
 delete mode 100644 tests/ui/await_holding_invalid.stderr
 create mode 100644 tests/ui/await_holding_lock.rs
 create mode 100644 tests/ui/await_holding_lock.stderr
 create mode 100644 tests/ui/await_holding_refcell_ref.rs
 create mode 100644 tests/ui/await_holding_refcell_ref.stderr

diff --git a/tests/ui/await_holding_invalid.rs b/tests/ui/await_holding_invalid.rs
deleted file mode 100644
index 45aa3e64292e..000000000000
--- a/tests/ui/await_holding_invalid.rs
+++ /dev/null
@@ -1,145 +0,0 @@
-// edition:2018
-#![warn(clippy::await_holding_lock, clippy::await_holding_refcell_ref)]
-
-use std::cell::RefCell;
-use std::sync::Mutex;
-
-async fn bad_lock(x: &Mutex<u32>) -> u32 {
-    let guard = x.lock().unwrap();
-    baz().await
-}
-
-async fn good_lock(x: &Mutex<u32>) -> u32 {
-    {
-        let guard = x.lock().unwrap();
-        let y = *guard + 1;
-    }
-    baz().await;
-    let guard = x.lock().unwrap();
-    47
-}
-
-async fn baz() -> u32 {
-    42
-}
-
-async fn also_bad_lock(x: &Mutex<u32>) -> u32 {
-    let first = baz().await;
-
-    let guard = x.lock().unwrap();
-
-    let second = baz().await;
-
-    let third = baz().await;
-
-    first + second + third
-}
-
-async fn not_good_lock(x: &Mutex<u32>) -> u32 {
-    let first = baz().await;
-
-    let second = {
-        let guard = x.lock().unwrap();
-        baz().await
-    };
-
-    let third = baz().await;
-
-    first + second + third
-}
-
-#[allow(clippy::manual_async_fn)]
-fn block_bad_lock(x: &Mutex<u32>) -> impl std::future::Future<Output = u32> + '_ {
-    async move {
-        let guard = x.lock().unwrap();
-        baz().await
-    }
-}
-
-async fn bad_refcell(x: &RefCell<u32>) -> u32 {
-    let b = x.borrow();
-    baz().await
-}
-
-async fn bad_mut_refcell(x: &RefCell<u32>) -> u32 {
-    let b = x.borrow_mut();
-    baz().await
-}
-
-async fn good_refcell(x: &RefCell<u32>) -> u32 {
-    {
-        let b = x.borrow_mut();
-        let y = *b + 1;
-    }
-    baz().await;
-    let b = x.borrow_mut();
-    47
-}
-
-async fn also_bad_refcell(x: &RefCell<u32>) -> u32 {
-    let first = baz().await;
-
-    let b = x.borrow_mut();
-
-    let second = baz().await;
-
-    let third = baz().await;
-
-    first + second + third
-}
-
-async fn less_bad_refcell(x: &RefCell<u32>) -> u32 {
-    let first = baz().await;
-
-    let b = x.borrow_mut();
-
-    let second = baz().await;
-
-    drop(b);
-
-    let third = baz().await;
-
-    first + second + third
-}
-
-async fn not_good_refcell(x: &RefCell<u32>) -> u32 {
-    let first = baz().await;
-
-    let second = {
-        let b = x.borrow_mut();
-        baz().await
-    };
-
-    let third = baz().await;
-
-    first + second + third
-}
-
-#[allow(clippy::manual_async_fn)]
-fn block_bad_refcell(x: &RefCell<u32>) -> impl std::future::Future<Output = u32> + '_ {
-    async move {
-        let b = x.borrow_mut();
-        baz().await
-    }
-}
-
-fn main() {
-    {
-        let m = Mutex::new(100);
-        good_lock(&m);
-        bad_lock(&m);
-        also_bad_lock(&m);
-        not_good_lock(&m);
-        block_bad_lock(&m);
-    }
-    {
-        let rc = RefCell::new(100);
-        good_refcell(&rc);
-        bad_refcell(&rc);
-        bad_mut_refcell(&rc);
-        also_bad_refcell(&rc);
-        less_bad_refcell(&rc);
-        not_good_refcell(&rc);
-        block_bad_refcell(&rc);
-    }
-}
diff --git a/tests/ui/await_holding_invalid.stderr b/tests/ui/await_holding_invalid.stderr
deleted file mode 100644
index c8d49820c020..000000000000
--- a/tests/ui/await_holding_invalid.stderr
+++ /dev/null
@@ -1,156 +0,0 @@
-error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
-  --> $DIR/await_holding_invalid.rs:8:9
-   |
-LL |     let guard = x.lock().unwrap();
-   |         ^^^^^
-   |
-   = note: `-D clippy::await-holding-lock` implied by `-D warnings`
-note: these are all the await points this lock is held through
-  --> $DIR/await_holding_invalid.rs:8:5
-   |
-LL | /     let guard = x.lock().unwrap();
-LL | |     baz().await
-LL | | }
-   | |_^
-
-error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
-  --> $DIR/await_holding_invalid.rs:29:9
-   |
-LL |     let guard = x.lock().unwrap();
-   |         ^^^^^
-   |
-note: these are all the await points this lock is held through
-  --> $DIR/await_holding_invalid.rs:29:5
-   |
-LL | /     let guard = x.lock().unwrap();
-LL | |
-LL | |     let second = baz().await;
-LL | |
-...  |
-LL | |     first + second + third
-LL | | }
-   | |_^
-
-error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
-  --> $DIR/await_holding_invalid.rs:42:13
-   |
-LL |         let guard = x.lock().unwrap();
-   |             ^^^^^
-   |
-note: these are all the await points this lock is held through
-  --> $DIR/await_holding_invalid.rs:42:9
-   |
-LL | /         let guard = x.lock().unwrap();
-LL | |         baz().await
-LL | |     };
-   | |_____^
-
-error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
-  --> $DIR/await_holding_invalid.rs:54:13
-   |
-LL |         let guard = x.lock().unwrap();
-   |             ^^^^^
-   |
-note: these are all the await points this lock is held through
-  --> $DIR/await_holding_invalid.rs:54:9
-   |
-LL | /         let guard = x.lock().unwrap();
-LL | |         baz().await
-LL | |     }
-   | |_____^
-
-error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
-  --> $DIR/await_holding_invalid.rs:60:9
-   |
-LL |     let b = x.borrow();
-   |         ^
-   |
-   = note: `-D clippy::await-holding-refcell-ref` implied by `-D warnings`
-note: these are all the await points this ref is held through
-  --> $DIR/await_holding_invalid.rs:60:5
-   |
-LL | /     let b = x.borrow();
-LL | |     baz().await
-LL | | }
-   | |_^
-
-error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
-  --> $DIR/await_holding_invalid.rs:65:9
-   |
-LL |     let b = x.borrow_mut();
-   |         ^
-   |
-note: these are all the await points this ref is held through
-  --> $DIR/await_holding_invalid.rs:65:5
-   |
-LL | /     let b = x.borrow_mut();
-LL | |     baz().await
-LL | | }
-   | |_^
-
-error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
-  --> $DIR/await_holding_invalid.rs:82:9
-   |
-LL |     let b = x.borrow_mut();
-   |         ^
-   |
-note: these are all the await points this ref is held through
-  --> $DIR/await_holding_invalid.rs:82:5
-   |
-LL | /     let b = x.borrow_mut();
-LL | |
-LL | |     let second = baz().await;
-LL | |
-...  |
-LL | |     first + second + third
-LL | | }
-   | |_^
-
-error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
-  --> $DIR/await_holding_invalid.rs:94:9
-   |
-LL |     let b = x.borrow_mut();
-   |         ^
-   |
-note: these are all the await points this ref is held through
-  --> $DIR/await_holding_invalid.rs:94:5
-   |
-LL | /     let b = x.borrow_mut();
-LL | |
-LL | |     let second = baz().await;
-LL | |
-...  |
-LL | |     first + second + third
-LL | | }
-   | |_^
-
-error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
-  --> $DIR/await_holding_invalid.rs:109:13
-   |
-LL |         let b = x.borrow_mut();
-   |             ^
-   |
-note: these are all the await points this ref is held through
-  --> $DIR/await_holding_invalid.rs:109:9
-   |
-LL | /         let b = x.borrow_mut();
-LL | |         baz().await
-LL | |     };
-   | |_____^
-
-error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
-  --> $DIR/await_holding_invalid.rs:121:13
-   |
-LL |         let b = x.borrow_mut();
-   |             ^
-   |
-note: these are all the await points this ref is held through
-  --> $DIR/await_holding_invalid.rs:121:9
-   |
-LL | /         let b = x.borrow_mut();
-LL | |         baz().await
-LL | |     }
-   | |_____^
-
-error: aborting due to 10 previous errors
-
diff --git a/tests/ui/await_holding_lock.rs b/tests/ui/await_holding_lock.rs
new file mode 100644
index 000000000000..0458950edee1
--- /dev/null
+++ b/tests/ui/await_holding_lock.rs
@@ -0,0 +1,65 @@
+// edition:2018
+#![warn(clippy::await_holding_lock)]
+
+use std::sync::Mutex;
+
+async fn bad(x: &Mutex<u32>) -> u32 {
+    let guard = x.lock().unwrap();
+    baz().await
+}
+
+async fn good(x: &Mutex<u32>) -> u32 {
+    {
+        let guard = x.lock().unwrap();
+        let y = *guard + 1;
+    }
+    baz().await;
+    let guard = x.lock().unwrap();
+    47
+}
+
+async fn baz() -> u32 {
+    42
+}
+
+async fn also_bad(x: &Mutex<u32>) -> u32 {
+    let first = baz().await;
+
+    let guard = x.lock().unwrap();
+
+    let second = baz().await;
+
+    let third = baz().await;
+
+    first + second + third
+}
+
+async fn not_good(x: &Mutex<u32>) -> u32 {
+    let first = baz().await;
+
+    let second = {
+        let guard = x.lock().unwrap();
+        baz().await
+    };
+
+    let third = baz().await;
+
+    first + second + third
+}
+
+#[allow(clippy::manual_async_fn)]
+fn block_bad(x: &Mutex<u32>) -> impl std::future::Future<Output = u32> + '_ {
+    async move {
+        let guard = x.lock().unwrap();
+        baz().await
+    }
+}
+
+fn main() {
+    let m = Mutex::new(100);
+    good(&m);
+    bad(&m);
+    also_bad(&m);
+    not_good(&m);
+    block_bad(&m);
+}
diff --git a/tests/ui/await_holding_lock.stderr b/tests/ui/await_holding_lock.stderr
new file mode 100644
index 000000000000..21bf49d16f04
--- /dev/null
+++ b/tests/ui/await_holding_lock.stderr
@@ -0,0 +1,63 @@
+error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
+  --> $DIR/await_holding_lock.rs:7:9
+   |
+LL |     let guard = x.lock().unwrap();
+   |         ^^^^^
+   |
+   = note: `-D clippy::await-holding-lock` implied by `-D warnings`
+note: these are all the await points this lock is held through
+  --> $DIR/await_holding_lock.rs:7:5
+   |
+LL | /     let guard = x.lock().unwrap();
+LL | |     baz().await
+LL | | }
+   | |_^
+
+error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
+  --> $DIR/await_holding_lock.rs:28:9
+   |
+LL |     let guard = x.lock().unwrap();
+   |         ^^^^^
+   |
+note: these are all the await points this lock is held through
+  --> $DIR/await_holding_lock.rs:28:5
+   |
+LL | /     let guard = x.lock().unwrap();
+LL | |
+LL | |     let second = baz().await;
+LL | |
+...  |
+LL | |     first + second + third
+LL | | }
+   | |_^
+
+error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
+  --> $DIR/await_holding_lock.rs:41:13
+   |
+LL |         let guard = x.lock().unwrap();
+   |             ^^^^^
+   |
+note: these are all the await points this lock is held through
+  --> $DIR/await_holding_lock.rs:41:9
+   |
+LL | /         let guard = x.lock().unwrap();
+LL | |         baz().await
+LL | |     };
+   | |_____^
+
+error: this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.
+  --> $DIR/await_holding_lock.rs:53:13
+   |
+LL |         let guard = x.lock().unwrap();
+   |             ^^^^^
+   |
+note: these are all the await points this lock is held through
+  --> $DIR/await_holding_lock.rs:53:9
+   |
+LL | /         let guard = x.lock().unwrap();
+LL | |         baz().await
+LL | |     }
+   | |_____^
+
+error: aborting due to 4 previous errors
+
diff --git a/tests/ui/await_holding_refcell_ref.rs b/tests/ui/await_holding_refcell_ref.rs
new file mode 100644
index 000000000000..88841597bb60
--- /dev/null
+++ b/tests/ui/await_holding_refcell_ref.rs
@@ -0,0 +1,86 @@
+// edition:2018
+#![warn(clippy::await_holding_refcell_ref)]
+
+use std::cell::RefCell;
+
+async fn bad(x: &RefCell<u32>) -> u32 {
+    let b = x.borrow();
+    baz().await
+}
+
+async fn bad_mut(x: &RefCell<u32>) -> u32 {
+    let b = x.borrow_mut();
+    baz().await
+}
+
+async fn good(x: &RefCell<u32>) -> u32 {
+    {
+        let b = x.borrow_mut();
+        let y = *b + 1;
+    }
+    baz().await;
+    let b = x.borrow_mut();
+    47
+}
+
+async fn baz() -> u32 {
+    42
+}
+
+async fn also_bad(x: &RefCell<u32>) -> u32 {
+    let first = baz().await;
+
+    let b = x.borrow_mut();
+
+    let second = baz().await;
+
+    let third = baz().await;
+
+    first + second + third
+}
+
+async fn less_bad(x: &RefCell<u32>) -> u32 {
+    let first = baz().await;
+
+    let b = x.borrow_mut();
+
+    let second = baz().await;
+
+    drop(b);
+
+    let third = baz().await;
+
+    first + second + third
+}
+
+async fn not_good(x: &RefCell<u32>) -> u32 {
+    let first = baz().await;
+
+    let second = {
+        let b = x.borrow_mut();
+        baz().await
+    };
+
+    let third = baz().await;
+
+    first + second + third
+}
+
+#[allow(clippy::manual_async_fn)]
+fn block_bad(x: &RefCell<u32>) -> impl std::future::Future<Output = u32> + '_ {
+    async move {
+        let b = x.borrow_mut();
+        baz().await
+    }
+}
+
+fn main() {
+    let rc = RefCell::new(100);
+    good(&rc);
+    bad(&rc);
+    bad_mut(&rc);
+    also_bad(&rc);
+    less_bad(&rc);
+    not_good(&rc);
+    block_bad(&rc);
+}
diff --git a/tests/ui/await_holding_refcell_ref.stderr b/tests/ui/await_holding_refcell_ref.stderr
new file mode 100644
index 000000000000..b504f0454913
--- /dev/null
+++ b/tests/ui/await_holding_refcell_ref.stderr
@@ -0,0 +1,95 @@
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_refcell_ref.rs:7:9
+   |
+LL |     let b = x.borrow();
+   |         ^
+   |
+   = note: `-D clippy::await-holding-refcell-ref` implied by `-D warnings`
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_refcell_ref.rs:7:5
+   |
+LL | /     let b = x.borrow();
+LL | |     baz().await
+LL | | }
+   | |_^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_refcell_ref.rs:12:9
+   |
+LL |     let b = x.borrow_mut();
+   |         ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_refcell_ref.rs:12:5
+   |
+LL | /     let b = x.borrow_mut();
+LL | |     baz().await
+LL | | }
+   | |_^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_refcell_ref.rs:33:9
+   |
+LL |     let b = x.borrow_mut();
+   |         ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_refcell_ref.rs:33:5
+   |
+LL | /     let b = x.borrow_mut();
+LL | |
+LL | |     let second = baz().await;
+LL | |
+...  |
+LL | |     first + second + third
+LL | | }
+   | |_^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_refcell_ref.rs:45:9
+   |
+LL |     let b = x.borrow_mut();
+   |         ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_refcell_ref.rs:45:5
+   |
+LL | /     let b = x.borrow_mut();
+LL | |
+LL | |     let second = baz().await;
+LL | |
+...  |
+LL | |     first + second + third
+LL | | }
+   | |_^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_refcell_ref.rs:60:13
+   |
+LL |         let b = x.borrow_mut();
+   |             ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_refcell_ref.rs:60:9
+   |
+LL | /         let b = x.borrow_mut();
+LL | |         baz().await
+LL | |     };
+   | |_____^
+
+error: this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.
+  --> $DIR/await_holding_refcell_ref.rs:72:13
+   |
+LL |         let b = x.borrow_mut();
+   |             ^
+   |
+note: these are all the await points this ref is held through
+  --> $DIR/await_holding_refcell_ref.rs:72:9
+   |
+LL | /         let b = x.borrow_mut();
+LL | |         baz().await
+LL | |     }
+   | |_____^
+
+error: aborting due to 6 previous errors
+