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Deprecate clippy lint

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This commit is contained in:
Michael Howell 2020-10-02 11:34:14 -07:00
parent cd159fd7f9
commit dceb81af1e
9 changed files with 21 additions and 111 deletions
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9
src/tools/clippy/clippy_lints/src/deprecated_lints.rs
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@ -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`"
}

73
src/tools/clippy/clippy_lints/src/drop_bounds.rs
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@ -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
);
}
}
}

9
src/tools/clippy/clippy_lints/src/lib.rs
View File

@ -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),

1
src/tools/clippy/clippy_lints/src/utils/paths.rs
View File

@ -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"];

7
src/tools/clippy/src/lintlist/mod.rs
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@ -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",

1
src/tools/clippy/tests/ui/deprecated.rs
View File

@ -8,5 +8,6 @@
#[warn(clippy::into_iter_on_array)]
#[warn(clippy::unused_label)]
#[warn(clippy::regex_macro)]
#[warn(clippy::drop_bounds)]
fn main() {}

8
src/tools/clippy/tests/ui/deprecated.stderr
View File

@ -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

8
src/tools/clippy/tests/ui/drop_bounds.rs
View File

@ -1,8 +0,0 @@
#![allow(unused)]
fn foo<T: Drop>() {}
fn bar<T>()
where
T: Drop,
{
}
fn main() {}

16
src/tools/clippy/tests/ui/drop_bounds.stderr
View File

@ -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