Deprecate Clippy drop_bounds lint

deprecate_clippy_drop_bounds.patch

diff --git a/src/tools/clippy/clippy_lints/src/deprecated_lints.rs b/src/tools/clippy/clippy_lints/src/deprecated_lints.rs
index c17a0e83330..c5884361dff 100644
--- a/src/tools/clippy/clippy_lints/src/deprecated_lints.rs
+++ b/src/tools/clippy/clippy_lints/src/deprecated_lints.rs
@@ -163,3 +163,12 @@ declare_deprecated_lint! {
     pub REGEX_MACRO,
     "the regex! macro has been removed from the regex crate in 2018"
 }
+
+declare_deprecated_lint! {
+    /// **What it does:** Nothing. This lint has been deprecated.
+    ///
+    /// **Deprecation reason:** This lint has been uplifted to rustc and is now called
+    /// `drop_bounds`.
+    pub DROP_BOUNDS,
+    "this lint has been uplifted to rustc and is now called `drop_bounds`"
+}
diff --git a/src/tools/clippy/clippy_lints/src/drop_bounds.rs b/src/tools/clippy/clippy_lints/src/drop_bounds.rs
deleted file mode 100644
index ec3b6afa630..00000000000
--- a/src/tools/clippy/clippy_lints/src/drop_bounds.rs
+++ /dev/null
@@ -1,73 +0,0 @@
-use crate::utils::{match_def_path, paths, span_lint};
-use if_chain::if_chain;
-use rustc_hir::{GenericBound, GenericParam, WhereBoundPredicate, WherePredicate};
-use rustc_lint::{LateContext, LateLintPass};
-use rustc_session::{declare_lint_pass, declare_tool_lint};
-
-declare_clippy_lint! {
-    /// **What it does:** Checks for generics with `std::ops::Drop` as bounds.
-    ///
-    /// **Why is this bad?** `Drop` bounds do not really accomplish anything.
-    /// A type may have compiler-generated drop glue without implementing the
-    /// `Drop` trait itself. The `Drop` trait also only has one method,
-    /// `Drop::drop`, and that function is by fiat not callable in user code.
-    /// So there is really no use case for using `Drop` in trait bounds.
-    ///
-    /// The most likely use case of a drop bound is to distinguish between types
-    /// that have destructors and types that don't. Combined with specialization,
-    /// a naive coder would write an implementation that assumed a type could be
-    /// trivially dropped, then write a specialization for `T: Drop` that actually
-    /// calls the destructor. Except that doing so is not correct; String, for
-    /// example, doesn't actually implement Drop, but because String contains a
-    /// Vec, assuming it can be trivially dropped will leak memory.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    /// ```rust
-    /// fn foo<T: Drop>() {}
-    /// ```
-    /// Could be written as:
-    /// ```rust
-    /// fn foo<T>() {}
-    /// ```
-    pub DROP_BOUNDS,
-    correctness,
-    "bounds of the form `T: Drop` are useless"
-}
-
-const DROP_BOUNDS_SUMMARY: &str = "bounds of the form `T: Drop` are useless, \
-                                   use `std::mem::needs_drop` to detect if a type has drop glue";
-
-declare_lint_pass!(DropBounds => [DROP_BOUNDS]);
-
-impl<'tcx> LateLintPass<'tcx> for DropBounds {
-    fn check_generic_param(&mut self, cx: &LateContext<'tcx>, p: &'tcx GenericParam<'_>) {
-        for bound in p.bounds.iter() {
-            lint_bound(cx, bound);
-        }
-    }
-    fn check_where_predicate(&mut self, cx: &LateContext<'tcx>, p: &'tcx WherePredicate<'_>) {
-        if let WherePredicate::BoundPredicate(WhereBoundPredicate { bounds, .. }) = p {
-            for bound in *bounds {
-                lint_bound(cx, bound);
-            }
-        }
-    }
-}
-
-fn lint_bound<'tcx>(cx: &LateContext<'tcx>, bound: &'tcx GenericBound<'_>) {
-    if_chain! {
-        if let GenericBound::Trait(t, _) = bound;
-        if let Some(def_id) = t.trait_ref.path.res.opt_def_id();
-        if match_def_path(cx, def_id, &paths::DROP_TRAIT);
-        then {
-            span_lint(
-                cx,
-                DROP_BOUNDS,
-                t.span,
-                DROP_BOUNDS_SUMMARY
-            );
-        }
-    }
-}
diff --git a/src/tools/clippy/clippy_lints/src/lib.rs b/src/tools/clippy/clippy_lints/src/lib.rs
index c3ff34e6e1e..70efdaeb9c6 100644
--- a/src/tools/clippy/clippy_lints/src/lib.rs
+++ b/src/tools/clippy/clippy_lints/src/lib.rs
@@ -179,7 +179,6 @@ mod derive;
 mod doc;
 mod double_comparison;
 mod double_parens;
-mod drop_bounds;
 mod drop_forget_ref;
 mod duration_subsec;
 mod else_if_without_else;
@@ -478,6 +477,10 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         "clippy::regex_macro",
         "the regex! macro has been removed from the regex crate in 2018",
     );
+    store.register_removed(
+        "clippy::drop_bounds",
+        "this lint has been uplifted to rustc and is now called `drop_bounds`",
+    );
     // end deprecated lints, do not remove this comment, it’s used in `update_lints`
 
     // begin register lints, do not remove this comment, it’s used in `update_lints`
@@ -532,7 +535,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &doc::NEEDLESS_DOCTEST_MAIN,
         &double_comparison::DOUBLE_COMPARISONS,
         &double_parens::DOUBLE_PARENS,
-        &drop_bounds::DROP_BOUNDS,
         &drop_forget_ref::DROP_COPY,
         &drop_forget_ref::DROP_REF,
         &drop_forget_ref::FORGET_COPY,
@@ -959,7 +961,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| box strings::StringLitAsBytes);
     store.register_late_pass(|| box derive::Derive);
     store.register_late_pass(|| box types::CharLitAsU8);
-    store.register_late_pass(|| box drop_bounds::DropBounds);
     store.register_late_pass(|| box get_last_with_len::GetLastWithLen);
     store.register_late_pass(|| box drop_forget_ref::DropForgetRef);
     store.register_late_pass(|| box empty_enum::EmptyEnum);
@@ -1282,7 +1283,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&doc::NEEDLESS_DOCTEST_MAIN),
         LintId::of(&double_comparison::DOUBLE_COMPARISONS),
         LintId::of(&double_parens::DOUBLE_PARENS),
-        LintId::of(&drop_bounds::DROP_BOUNDS),
         LintId::of(&drop_forget_ref::DROP_COPY),
         LintId::of(&drop_forget_ref::DROP_REF),
         LintId::of(&drop_forget_ref::FORGET_COPY),
@@ -1714,7 +1714,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&copies::IF_SAME_THEN_ELSE),
         LintId::of(&derive::DERIVE_HASH_XOR_EQ),
         LintId::of(&derive::DERIVE_ORD_XOR_PARTIAL_ORD),
-        LintId::of(&drop_bounds::DROP_BOUNDS),
         LintId::of(&drop_forget_ref::DROP_COPY),
         LintId::of(&drop_forget_ref::DROP_REF),
         LintId::of(&drop_forget_ref::FORGET_COPY),
diff --git a/src/tools/clippy/clippy_lints/src/utils/paths.rs b/src/tools/clippy/clippy_lints/src/utils/paths.rs
index 1583afad208..be837a61dc0 100644
--- a/src/tools/clippy/clippy_lints/src/utils/paths.rs
+++ b/src/tools/clippy/clippy_lints/src/utils/paths.rs
@@ -31,7 +31,6 @@ pub const DISPLAY_FMT_METHOD: [&str; 4] = ["core", "fmt", "Display", "fmt"];
 pub const DISPLAY_TRAIT: [&str; 3] = ["core", "fmt", "Display"];
 pub const DOUBLE_ENDED_ITERATOR: [&str; 4] = ["core", "iter", "traits", "DoubleEndedIterator"];
 pub const DROP: [&str; 3] = ["core", "mem", "drop"];
-pub const DROP_TRAIT: [&str; 4] = ["core", "ops", "drop", "Drop"];
 pub const DURATION: [&str; 3] = ["core", "time", "Duration"];
 pub const EARLY_CONTEXT: [&str; 4] = ["rustc", "lint", "context", "EarlyContext"];
 pub const EXIT: [&str; 3] = ["std", "process", "exit"];
diff --git a/src/tools/clippy/src/lintlist/mod.rs b/src/tools/clippy/src/lintlist/mod.rs
index 9603023ed06..f6d529de9a3 100644
--- a/src/tools/clippy/src/lintlist/mod.rs
+++ b/src/tools/clippy/src/lintlist/mod.rs
@@ -423,13 +423,6 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
         deprecation: None,
         module: "double_parens",
     },
-    Lint {
-        name: "drop_bounds",
-        group: "correctness",
-        desc: "bounds of the form `T: Drop` are useless",
-        deprecation: None,
-        module: "drop_bounds",
-    },
     Lint {
         name: "drop_copy",
         group: "correctness",
diff --git a/src/tools/clippy/tests/ui/deprecated.rs b/src/tools/clippy/tests/ui/deprecated.rs
index 3eefb232780..9e32fe36ece 100644
--- a/src/tools/clippy/tests/ui/deprecated.rs
+++ b/src/tools/clippy/tests/ui/deprecated.rs
@@ -8,5 +8,6 @@
 #[warn(clippy::into_iter_on_array)]
 #[warn(clippy::unused_label)]
 #[warn(clippy::regex_macro)]
+#[warn(clippy::drop_bounds)]
 
 fn main() {}
diff --git a/src/tools/clippy/tests/ui/deprecated.stderr b/src/tools/clippy/tests/ui/deprecated.stderr
index a80e2bf31fe..d3400a7be09 100644
--- a/src/tools/clippy/tests/ui/deprecated.stderr
+++ b/src/tools/clippy/tests/ui/deprecated.stderr
@@ -60,11 +60,17 @@ error: lint `clippy::regex_macro` has been removed: `the regex! macro has been r
 LL | #[warn(clippy::regex_macro)]
    |        ^^^^^^^^^^^^^^^^^^^
 
+error: lint `clippy::drop_bounds` has been removed: `this lint has been uplifted to rustc and is now called `drop_bounds``
+  --> $DIR/deprecated.rs:11:8
+   |
+LL | #[warn(clippy::drop_bounds)]
+   |        ^^^^^^^^^^^^^^^^^^^
+
 error: lint `clippy::str_to_string` has been removed: `using `str::to_string` is common even today and specialization will likely happen soon`
   --> $DIR/deprecated.rs:1:8
    |
 LL | #[warn(clippy::str_to_string)]
    |        ^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 11 previous errors
+error: aborting due to 12 previous errors
 
diff --git a/src/tools/clippy/tests/ui/drop_bounds.rs b/src/tools/clippy/tests/ui/drop_bounds.rs
deleted file mode 100644
index 6d6a9dc0783..00000000000
--- a/src/tools/clippy/tests/ui/drop_bounds.rs
+++ /dev/null
@@ -1,8 +0,0 @@
-#![allow(unused)]
-fn foo<T: Drop>() {}
-fn bar<T>()
-where
-    T: Drop,
-{
-}
-fn main() {}
diff --git a/src/tools/clippy/tests/ui/drop_bounds.stderr b/src/tools/clippy/tests/ui/drop_bounds.stderr
deleted file mode 100644
index 8208c0ed7e3..00000000000
--- a/src/tools/clippy/tests/ui/drop_bounds.stderr
+++ /dev/null
@@ -1,16 +0,0 @@
-error: bounds of the form `T: Drop` are useless, use `std::mem::needs_drop` to detect if a type has drop glue
-  --> $DIR/drop_bounds.rs:2:11
-   |
-LL | fn foo<T: Drop>() {}
-   |           ^^^^
-   |
-   = note: `#[deny(clippy::drop_bounds)]` on by default
-
-error: bounds of the form `T: Drop` are useless, use `std::mem::needs_drop` to detect if a type has drop glue
-  --> $DIR/drop_bounds.rs:5:8
-   |
-LL |     T: Drop,
-   |        ^^^^
-
-error: aborting due to 2 previous errors
-