From ac5e9c8d2691da5a3872a8eec97ce694193c1e5c Mon Sep 17 00:00:00 2001
From: Cameron Steffen <cam.steffen94@gmail.com>
Date: Fri, 5 Feb 2021 14:45:24 -0600
Subject: [PATCH 1/2] Fix let_underscore_drop implements Drop logic
This fixes false positives and false negatives.
---
clippy_lints/src/let_underscore.rs | 13 ++-----------
tests/ui/let_underscore_drop.rs | 8 ++++++++
2 files changed, 10 insertions(+), 11 deletions(-)
diff --git a/clippy_lints/src/let_underscore.rs b/clippy_lints/src/let_underscore.rs
index 6a5a77f8690..7e96dfcc7da 100644
--- a/clippy_lints/src/let_underscore.rs
+++ b/clippy_lints/src/let_underscore.rs
@@ -5,7 +5,7 @@ use rustc_middle::lint::in_external_macro;
use rustc_middle::ty::subst::GenericArgKind;
use rustc_session::{declare_lint_pass, declare_tool_lint};
-use crate::utils::{implements_trait, is_must_use_func_call, is_must_use_ty, match_type, paths, span_lint_and_help};
+use crate::utils::{is_must_use_func_call, is_must_use_ty, match_type, paths, span_lint_and_help};
declare_clippy_lint! {
/// **What it does:** Checks for `let _ = <expr>`
@@ -125,15 +125,6 @@ impl<'tcx> LateLintPass<'tcx> for LetUnderscore {
GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => false,
});
- let implements_drop = cx.tcx.lang_items().drop_trait().map_or(false, |drop_trait|
- init_ty.walk().any(|inner| match inner.unpack() {
- GenericArgKind::Type(inner_ty) => {
- implements_trait(cx, inner_ty, drop_trait, &[])
- },
-
- GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => false,
- })
- );
if contains_sync_guard {
span_lint_and_help(
cx,
@@ -144,7 +135,7 @@ impl<'tcx> LateLintPass<'tcx> for LetUnderscore {
"consider using an underscore-prefixed named \
binding or dropping explicitly with `std::mem::drop`"
)
- } else if implements_drop {
+ } else if init_ty.needs_drop(cx.tcx, cx.param_env) {
span_lint_and_help(
cx,
LET_UNDERSCORE_DROP,
diff --git a/tests/ui/let_underscore_drop.rs b/tests/ui/let_underscore_drop.rs
index 98593edb9c5..50744f81c3c 100644
--- a/tests/ui/let_underscore_drop.rs
+++ b/tests/ui/let_underscore_drop.rs
@@ -16,4 +16,12 @@ fn main() {
let _ = Box::new(());
let _ = Droppable;
let _ = Some(Droppable);
+
+ // no lint for reference
+ let _ = droppable_ref();
+}
+
+#[must_use]
+fn droppable_ref() -> &'static mut Droppable {
+ unimplemented!()
}
From 40ce05654be9f4f6fb80e295f3eb05bee211cfc7 Mon Sep 17 00:00:00 2001
From: Cameron Steffen <cam.steffen94@gmail.com>
Date: Fri, 5 Feb 2021 14:55:09 -0600
Subject: [PATCH 2/2] Eat dogfood
---
clippy_dev/src/serve.rs | 2 +-
clippy_lints/src/macro_use.rs | 2 +-
src/main.rs | 2 +-
3 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/clippy_dev/src/serve.rs b/clippy_dev/src/serve.rs
index faa94859601..d13c27a1957 100644
--- a/clippy_dev/src/serve.rs
+++ b/clippy_dev/src/serve.rs
@@ -34,7 +34,7 @@ pub fn run(port: u16, lint: Option<&str>) -> ! {
// Give some time for python to start
thread::sleep(Duration::from_millis(500));
// Launch browser after first export.py has completed and http.server is up
- let _ = opener::open(url);
+ let _result = opener::open(url);
});
}
thread::sleep(Duration::from_millis(1000));
diff --git a/clippy_lints/src/macro_use.rs b/clippy_lints/src/macro_use.rs
index bb52888883a..40f04bd677d 100644
--- a/clippy_lints/src/macro_use.rs
+++ b/clippy_lints/src/macro_use.rs
@@ -160,7 +160,7 @@ impl<'tcx> LateLintPass<'tcx> for MacroUseImports {
let found_idx = self.mac_refs.iter().position(|mac| import.ends_with(&mac.name));
if let Some(idx) = found_idx {
- let _ = self.mac_refs.remove(idx);
+ self.mac_refs.remove(idx);
let seg = import.split("::").collect::<Vec<_>>();
match seg.as_slice() {
diff --git a/src/main.rs b/src/main.rs
index ea06743394d..b4423ce9ec7 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -195,7 +195,7 @@ mod tests {
#[should_panic]
fn fix_without_unstable() {
let args = "cargo clippy --fix".split_whitespace().map(ToString::to_string);
- let _ = ClippyCmd::new(args);
+ ClippyCmd::new(args);
}
#[test]