Auto merge of #4930 - flip1995:unused_label, r=phansch

Deprecate unused_label lint

This lint was uplifted/turned into warn-by-default in rustc

Fixes #4925

changelog: Deprecate [`unused_label`] lint

README.md

@@ -6,7 +6,7 @@
 
 A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
 
-[There are 340 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
+[There are 339 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
 
 We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:
 

clippy_lints/src/deprecated_lints.rs

@@ -138,3 +138,12 @@ declare_deprecated_lint! {
     pub INTO_ITER_ON_ARRAY,
     "this lint has been uplifted to rustc and is now called `array_into_iter`"
 }
+
+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
+    /// `unused_labels`.
+    pub UNUSED_LABEL,
+    "this lint has been uplifted to rustc and is now called `unused_labels`"
+}

clippy_lints/src/lib.rs

@@ -292,7 +292,6 @@ pub mod types;
 pub mod unicode;
 pub mod unsafe_removed_from_name;
 pub mod unused_io_amount;
-pub mod unused_label;
 pub mod unused_self;
 pub mod unwrap;
 pub mod use_self;
@@ -446,6 +445,10 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
         "clippy::into_iter_on_array",
         "this lint has been uplifted to rustc and is now called `array_into_iter`",
     );
+    store.register_removed(
+        "clippy::unused_label",
+        "this lint has been uplifted to rustc and is now called `unused_labels`",
+    );
     // 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`
@@ -774,7 +777,6 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
         &unicode::ZERO_WIDTH_SPACE,
         &unsafe_removed_from_name::UNSAFE_REMOVED_FROM_NAME,
         &unused_io_amount::UNUSED_IO_AMOUNT,
-        &unused_label::UNUSED_LABEL,
         &unused_self::UNUSED_SELF,
         &unwrap::PANICKING_UNWRAP,
         &unwrap::UNNECESSARY_UNWRAP,
@@ -868,7 +870,6 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
     store.register_late_pass(|| box format::UselessFormat);
     store.register_late_pass(|| box swap::Swap);
     store.register_late_pass(|| box overflow_check_conditional::OverflowCheckConditional);
-    store.register_late_pass(|| box unused_label::UnusedLabel);
     store.register_late_pass(|| box new_without_default::NewWithoutDefault::default());
     let blacklisted_names = conf.blacklisted_names.iter().cloned().collect::<FxHashSet<_>>();
     store.register_late_pass(move || box blacklisted_name::BlacklistedName::new(blacklisted_names.clone()));
@@ -1302,7 +1303,6 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
         LintId::of(&unicode::ZERO_WIDTH_SPACE),
         LintId::of(&unsafe_removed_from_name::UNSAFE_REMOVED_FROM_NAME),
         LintId::of(&unused_io_amount::UNUSED_IO_AMOUNT),
-        LintId::of(&unused_label::UNUSED_LABEL),
         LintId::of(&unwrap::PANICKING_UNWRAP),
         LintId::of(&unwrap::UNNECESSARY_UNWRAP),
         LintId::of(&vec::USELESS_VEC),
@@ -1482,7 +1482,6 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
         LintId::of(&types::UNIT_ARG),
         LintId::of(&types::UNNECESSARY_CAST),
         LintId::of(&types::VEC_BOX),
-        LintId::of(&unused_label::UNUSED_LABEL),
         LintId::of(&unwrap::UNNECESSARY_UNWRAP),
         LintId::of(&zero_div_zero::ZERO_DIVIDED_BY_ZERO),
     ]);

clippy_lints/src/unused_label.rs

@@ -1,83 +0,0 @@
-use crate::utils::span_lint;
-use rustc::declare_lint_pass;
-use rustc::hir;
-use rustc::hir::intravisit::{walk_expr, walk_fn, FnKind, NestedVisitorMap, Visitor};
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc_data_structures::fx::FxHashMap;
-use rustc_session::declare_tool_lint;
-use syntax::source_map::Span;
-use syntax::symbol::Symbol;
-
-declare_clippy_lint! {
-    /// **What it does:** Checks for unused labels.
-    ///
-    /// **Why is this bad?** Maybe the label should be used in which case there is
-    /// an error in the code or it should be removed.
-    ///
-    /// **Known problems:** Hopefully none.
-    ///
-    /// **Example:**
-    /// ```rust,ignore
-    /// fn unused_label() {
-    ///     'label: for i in 1..2 {
-    ///         if i > 4 { continue }
-    ///     }
-    /// ```
-    pub UNUSED_LABEL,
-    complexity,
-    "unused labels"
-}
-
-struct UnusedLabelVisitor<'a, 'tcx> {
-    labels: FxHashMap<Symbol, Span>,
-    cx: &'a LateContext<'a, 'tcx>,
-}
-
-declare_lint_pass!(UnusedLabel => [UNUSED_LABEL]);
-
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedLabel {
-    fn check_fn(
-        &mut self,
-        cx: &LateContext<'a, 'tcx>,
-        kind: FnKind<'tcx>,
-        decl: &'tcx hir::FnDecl,
-        body: &'tcx hir::Body,
-        span: Span,
-        fn_id: hir::HirId,
-    ) {
-        if span.from_expansion() {
-            return;
-        }
-
-        let mut v = UnusedLabelVisitor {
-            cx,
-            labels: FxHashMap::default(),
-        };
-        walk_fn(&mut v, kind, decl, body.id(), span, fn_id);
-
-        for (label, span) in v.labels {
-            span_lint(cx, UNUSED_LABEL, span, &format!("unused label `{}`", label));
-        }
-    }
-}
-
-impl<'a, 'tcx> Visitor<'tcx> for UnusedLabelVisitor<'a, 'tcx> {
-    fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
-        match expr.kind {
-            hir::ExprKind::Break(destination, _) | hir::ExprKind::Continue(destination) => {
-                if let Some(label) = destination.label {
-                    self.labels.remove(&label.ident.name);
-                }
-            },
-            hir::ExprKind::Loop(_, Some(label), _) => {
-                self.labels.insert(label.ident.name, expr.span);
-            },
-            _ => (),
-        }
-
-        walk_expr(self, expr);
-    }
-    fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
-        NestedVisitorMap::All(&self.cx.tcx.hir())
-    }
-}

src/lintlist/mod.rs

@@ -6,7 +6,7 @@ pub use lint::Lint;
 pub use lint::LINT_LEVELS;
 
 // begin lint list, do not remove this comment, it’s used in `update_lints`
-pub const ALL_LINTS: [Lint; 340] = [
+pub const ALL_LINTS: [Lint; 339] = [
     Lint {
         name: "absurd_extreme_comparisons",
         group: "correctness",
@@ -2177,13 +2177,6 @@ pub const ALL_LINTS: [Lint; 340] = [
         deprecation: None,
         module: "unused_io_amount",
     },
-    Lint {
-        name: "unused_label",
-        group: "complexity",
-        desc: "unused labels",
-        deprecation: None,
-        module: "unused_label",
-    },
     Lint {
         name: "unused_self",
         group: "pedantic",

tests/ui/deprecated.rs

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

tests/ui/deprecated.stderr

@@ -48,11 +48,17 @@ error: lint `clippy::into_iter_on_array` has been removed: `this lint has been u
 LL | #[warn(clippy::into_iter_on_array)]
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+error: lint `clippy::unused_label` has been removed: `this lint has been uplifted to rustc and is now called `unused_labels``
+  --> $DIR/deprecated.rs:9:8
+   |
+LL | #[warn(clippy::unused_label)]
+   |        ^^^^^^^^^^^^^^^^^^^^
+
 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 9 previous errors
+error: aborting due to 10 previous errors
 

tests/ui/empty_loop.rs

@@ -1,7 +1,6 @@
 // aux-build:macro_rules.rs
 
 #![warn(clippy::empty_loop)]
-#![allow(clippy::unused_label)]
 
 #[macro_use]
 extern crate macro_rules;

tests/ui/empty_loop.stderr

@@ -1,5 +1,5 @@
 error: empty `loop {}` detected. You may want to either use `panic!()` or add `std::thread::sleep(..);` to the loop body.
-  --> $DIR/empty_loop.rs:10:5
+  --> $DIR/empty_loop.rs:9:5
    |
 LL |     loop {}
    |     ^^^^^^^
@@ -7,13 +7,13 @@ LL |     loop {}
    = note: `-D clippy::empty-loop` implied by `-D warnings`
 
 error: empty `loop {}` detected. You may want to either use `panic!()` or add `std::thread::sleep(..);` to the loop body.
-  --> $DIR/empty_loop.rs:12:9
+  --> $DIR/empty_loop.rs:11:9
    |
 LL |         loop {}
    |         ^^^^^^^
 
 error: empty `loop {}` detected. You may want to either use `panic!()` or add `std::thread::sleep(..);` to the loop body.
-  --> $DIR/empty_loop.rs:16:9
+  --> $DIR/empty_loop.rs:15:9
    |
 LL |         'inner: loop {}
    |         ^^^^^^^^^^^^^^^

tests/ui/unused_labels.rs

@@ -1,35 +0,0 @@
-#![allow(dead_code, clippy::items_after_statements, clippy::never_loop)]
-#![warn(clippy::unused_label)]
-
-fn unused_label() {
-    'label: for i in 1..2 {
-        if i > 4 {
-            continue;
-        }
-    }
-}
-
-fn foo() {
-    'same_label_in_two_fns: loop {
-        break 'same_label_in_two_fns;
-    }
-}
-
-fn bla() {
-    'a: loop {
-        break;
-    }
-    fn blub() {}
-}
-
-fn main() {
-    'a: for _ in 0..10 {
-        while let Some(42) = None {
-            continue 'a;
-        }
-    }
-
-    'same_label_in_two_fns: loop {
-        let _ = 1;
-    }
-}

tests/ui/unused_labels.stderr

@@ -1,30 +0,0 @@
-error: unused label `'label`
-  --> $DIR/unused_labels.rs:5:5
-   |
-LL | /     'label: for i in 1..2 {
-LL | |         if i > 4 {
-LL | |             continue;
-LL | |         }
-LL | |     }
-   | |_____^
-   |
-   = note: `-D clippy::unused-label` implied by `-D warnings`
-
-error: unused label `'a`
-  --> $DIR/unused_labels.rs:19:5
-   |
-LL | /     'a: loop {
-LL | |         break;
-LL | |     }
-   | |_____^
-
-error: unused label `'same_label_in_two_fns`
-  --> $DIR/unused_labels.rs:32:5
-   |
-LL | /     'same_label_in_two_fns: loop {
-LL | |         let _ = 1;
-LL | |     }
-   | |_____^
-
-error: aborting due to 3 previous errors
-