Auto merge of #82663 - jyn514:rollup-xh3cb0c, r=jyn514

Rollup of 8 pull requests

Successful merges:

 - #81210 (BTreeMap: correct node size test case for choices of B)
 - #82360 (config.toml parsing error improvements)
 - #82428 (Update mdbook)
 - #82480 (Remove `ENABLE_DOWNLOAD_RUSTC` constant)
 - #82578 (Add some diagnostic items for Clippy)
 - #82620 (Apply lint restrictions from renamed lints)
 - #82635 (Fix typos in rustc_infer::infer::nll_relate)
 - #82645 (Clarify that SyncOnceCell::set blocks.)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Cargo.lock

@@ -1767,7 +1767,7 @@ dependencies = [
  "regex",
  "serde",
  "serde_json",
- "shlex",
+ "shlex 0.1.1",
 ]
 
 [[package]]
@@ -2122,9 +2122,9 @@ dependencies = [
 
 [[package]]
 name = "mdbook"
-version = "0.4.6"
+version = "0.4.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b3d948b64449003363127ed6c6139f03273982c3fe97da4cb3dee933e38ce38f"
+checksum = "28f6a882f3880ec68e96f60d6b543c34941e2f307ad10e2992e4db9acfe96529"
 dependencies = [
  "ammonia",
  "anyhow",
@@ -2142,7 +2142,7 @@ dependencies = [
  "serde",
  "serde_derive",
  "serde_json",
- "shlex",
+ "shlex 1.0.0",
  "tempfile",
  "toml",
 ]
@@ -4858,6 +4858,12 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7fdf1b9db47230893d76faad238fd6097fd6d6a9245cd7a4d90dbd639536bbd2"
 
+[[package]]
+name = "shlex"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42a568c8f2cd051a4d283bd6eb0343ac214c1b0f1ac19f93e1175b2dee38c73d"
+
 [[package]]
 name = "signal-hook-registry"
 version = "1.2.1"

compiler/rustc_infer/src/infer/nll_relate/mod.rs

@@ -44,7 +44,7 @@ where
 {
     infcx: &'me InferCtxt<'me, 'tcx>,
 
-    /// Callback to use when we deduce an outlives relationship
+    /// Callback to use when we deduce an outlives relationship.
     delegate: D,
 
     /// How are we relating `a` and `b`?
@@ -768,7 +768,7 @@ impl<'me, 'tcx> TypeVisitor<'tcx> for ScopeInstantiator<'me, 'tcx> {
     }
 }
 
-/// The "type generalize" is used when handling inference variables.
+/// The "type generalizer" is used when handling inference variables.
 ///
 /// The basic strategy for handling a constraint like `?A <: B` is to
 /// apply a "generalization strategy" to the type `B` -- this replaces

compiler/rustc_lint/src/levels.rs

@@ -321,17 +321,18 @@ impl<'s> LintLevelsBuilder<'s> {
                     None
                 };
                 let name = meta_item.path.segments.last().expect("empty lint name").ident.name;
-                match store.check_lint_name(&name.as_str(), tool_name) {
+                let lint_result = store.check_lint_name(&name.as_str(), tool_name);
+                match &lint_result {
                     CheckLintNameResult::Ok(ids) => {
                         let src = LintLevelSource::Node(name, li.span(), reason);
-                        for &id in ids {
+                        for &id in *ids {
                             self.check_gated_lint(id, attr.span);
                             self.insert_spec(&mut specs, id, (level, src));
                         }
                     }
 
                     CheckLintNameResult::Tool(result) => {
-                        match result {
+                        match *result {
                             Ok(ids) => {
                                 let complete_name = &format!("{}::{}", tool_name.unwrap(), name);
                                 let src = LintLevelSource::Node(
@@ -343,7 +344,7 @@ impl<'s> LintLevelsBuilder<'s> {
                                     self.insert_spec(&mut specs, *id, (level, src));
                                 }
                             }
-                            Err((Some(ids), new_lint_name)) => {
+                            Err((Some(ids), ref new_lint_name)) => {
                                 let lint = builtin::RENAMED_AND_REMOVED_LINTS;
                                 let (lvl, src) =
                                     self.sets.get_lint_level(lint, self.cur, Some(&specs), &sess);
@@ -392,21 +393,21 @@ impl<'s> LintLevelsBuilder<'s> {
 
                     CheckLintNameResult::Warning(msg, renamed) => {
                         let lint = builtin::RENAMED_AND_REMOVED_LINTS;
-                        let (level, src) =
+                        let (renamed_lint_level, src) =
                             self.sets.get_lint_level(lint, self.cur, Some(&specs), &sess);
                         struct_lint_level(
                             self.sess,
                             lint,
-                            level,
+                            renamed_lint_level,
                             src,
                             Some(li.span().into()),
                             |lint| {
                                 let mut err = lint.build(&msg);
-                                if let Some(new_name) = renamed {
+                                if let Some(new_name) = &renamed {
                                     err.span_suggestion(
                                         li.span(),
                                         "use the new name",
-                                        new_name,
+                                        new_name.to_string(),
                                         Applicability::MachineApplicable,
                                     );
                                 }
@@ -444,6 +445,22 @@ impl<'s> LintLevelsBuilder<'s> {
                         );
                     }
                 }
+                // If this lint was renamed, apply the new lint instead of ignoring the attribute.
+                // This happens outside of the match because the new lint should be applied even if
+                // we don't warn about the name change.
+                if let CheckLintNameResult::Warning(_, Some(new_name)) = lint_result {
+                    // Ignore any errors or warnings that happen because the new name is inaccurate
+                    if let CheckLintNameResult::Ok(ids) =
+                        store.check_lint_name(&new_name, tool_name)
+                    {
+                        let src =
+                            LintLevelSource::Node(Symbol::intern(&new_name), li.span(), reason);
+                        for &id in ids {
+                            self.check_gated_lint(id, attr.span);
+                            self.insert_spec(&mut specs, id, (level, src));
+                        }
+                    }
+                }
             }
         }
 

compiler/rustc_span/src/symbol.rs

@@ -126,6 +126,9 @@ symbols! {
         Argument,
         ArgumentV1,
         Arguments,
+        BTreeMap,
+        BTreeSet,
+        BinaryHeap,
         C,
         CString,
         Center,
@@ -163,6 +166,7 @@ symbols! {
         Iterator,
         Layout,
         Left,
+        LinkedList,
         LintPass,
         None,
         Ok,
@@ -191,6 +195,7 @@ symbols! {
         RangeToInclusive,
         Rc,
         Ready,
+        Receiver,
         Result,
         Return,
         Right,
@@ -592,6 +597,8 @@ symbols! {
         gt,
         half_open_range_patterns,
         hash,
+        hashmap_type,
+        hashset_type,
         hexagon_target_feature,
         hidden,
         homogeneous_aggregate,
@@ -1256,6 +1263,7 @@ symbols! {
         variant_count,
         vec,
         vec_type,
+        vecdeque_type,
         version,
         vis,
         visible_private_types,

config.toml.example

@@ -637,7 +637,9 @@ changelog-seen = 2
 # The full path to the musl libdir.
 #musl-libdir = musl-root/lib
 
-# The root location of the `wasm32-wasi` sysroot.
+# The root location of the `wasm32-wasi` sysroot. Only used for the
+# `wasm32-wasi` target. If you are building wasm32-wasi target, make sure to
+# create a `[target.wasm32-wasi]` section and move this field there.
 #wasi-root = "..."
 
 # Used in testing for configuring where the QEMU images are located, you

library/alloc/benches/btree/map.rs

@@ -296,11 +296,6 @@ fn fat_val_map(n: usize) -> BTreeMap<usize, [usize; FAT]> {
     (0..n).map(|i| (i, [i; FAT])).collect::<BTreeMap<_, _>>()
 }
 
-// The returned map has large keys and values.
-fn fat_map(n: usize) -> BTreeMap<[usize; FAT], [usize; FAT]> {
-    (0..n).map(|i| ([i; FAT], [i; FAT])).collect::<BTreeMap<_, _>>()
-}
-
 #[bench]
 pub fn clone_slim_100(b: &mut Bencher) {
     let src = slim_map(100);
@@ -513,74 +508,3 @@ pub fn clone_fat_val_100_and_remove_half(b: &mut Bencher) {
         map
     })
 }
-
-#[bench]
-pub fn clone_fat_100(b: &mut Bencher) {
-    let src = fat_map(100);
-    b.iter(|| src.clone())
-}
-
-#[bench]
-pub fn clone_fat_100_and_clear(b: &mut Bencher) {
-    let src = fat_map(100);
-    b.iter(|| src.clone().clear())
-}
-
-#[bench]
-pub fn clone_fat_100_and_drain_all(b: &mut Bencher) {
-    let src = fat_map(100);
-    b.iter(|| src.clone().drain_filter(|_, _| true).count())
-}
-
-#[bench]
-pub fn clone_fat_100_and_drain_half(b: &mut Bencher) {
-    let src = fat_map(100);
-    b.iter(|| {
-        let mut map = src.clone();
-        assert_eq!(map.drain_filter(|i, _| i[0] % 2 == 0).count(), 100 / 2);
-        assert_eq!(map.len(), 100 / 2);
-    })
-}
-
-#[bench]
-pub fn clone_fat_100_and_into_iter(b: &mut Bencher) {
-    let src = fat_map(100);
-    b.iter(|| src.clone().into_iter().count())
-}
-
-#[bench]
-pub fn clone_fat_100_and_pop_all(b: &mut Bencher) {
-    let src = fat_map(100);
-    b.iter(|| {
-        let mut map = src.clone();
-        while map.pop_first().is_some() {}
-        map
-    });
-}
-
-#[bench]
-pub fn clone_fat_100_and_remove_all(b: &mut Bencher) {
-    let src = fat_map(100);
-    b.iter(|| {
-        let mut map = src.clone();
-        while let Some(elt) = map.iter().map(|(&i, _)| i).next() {
-            let v = map.remove(&elt);
-            debug_assert!(v.is_some());
-        }
-        map
-    });
-}
-
-#[bench]
-pub fn clone_fat_100_and_remove_half(b: &mut Bencher) {
-    let src = fat_map(100);
-    b.iter(|| {
-        let mut map = src.clone();
-        for i in (0..100).step_by(2) {
-            let v = map.remove(&[i; FAT]);
-            debug_assert!(v.is_some());
-        }
-        assert_eq!(map.len(), 100 / 2);
-        map
-    })
-}

library/alloc/src/collections/binary_heap.rs

@@ -247,6 +247,7 @@ use super::SpecExtend;
 /// [peek]: BinaryHeap::peek
 /// [peek\_mut]: BinaryHeap::peek_mut
 #[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(not(test), rustc_diagnostic_item = "BinaryHeap")]
 pub struct BinaryHeap<T> {
     data: Vec<T>,
 }

library/alloc/src/collections/btree/map.rs

@@ -138,6 +138,7 @@ pub(super) const MIN_LEN: usize = node::MIN_LEN_AFTER_SPLIT;
 /// *stat += random_stat_buff();
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(not(test), rustc_diagnostic_item = "BTreeMap")]
 pub struct BTreeMap<K, V> {
     root: Option<Root<K, V>>,
     length: usize,

library/alloc/src/collections/btree/map/tests.rs

@@ -136,8 +136,9 @@ impl<'a, K: 'a, V: 'a> NodeRef<marker::Immut<'a>, K, V, marker::LeafOrInternal>
     }
 }
 
-// Tests our value of MIN_INSERTS_HEIGHT_2. It may change according to the
+// Tests our value of MIN_INSERTS_HEIGHT_2. Failure may mean you just need to
-// implementation of insertion, but it's best to be aware of when it does.
+// adapt that value to match a change in node::CAPACITY or the choices made
+// during insertion, otherwise other test cases may fail or be less useful.
 #[test]
 fn test_levels() {
     let mut map = BTreeMap::new();

library/alloc/src/collections/btree/node/tests.rs

@@ -95,7 +95,7 @@ fn test_partial_eq() {
 #[cfg(target_arch = "x86_64")]
 fn test_sizes() {
     assert_eq!(core::mem::size_of::<LeafNode<(), ()>>(), 16);
-    assert_eq!(core::mem::size_of::<LeafNode<i64, i64>>(), 16 + CAPACITY * 8 * 2);
+    assert_eq!(core::mem::size_of::<LeafNode<i64, i64>>(), 16 + CAPACITY * 2 * 8);
-    assert_eq!(core::mem::size_of::<InternalNode<(), ()>>(), 112);
+    assert_eq!(core::mem::size_of::<InternalNode<(), ()>>(), 16 + (CAPACITY + 1) * 8);
-    assert_eq!(core::mem::size_of::<InternalNode<i64, i64>>(), 112 + CAPACITY * 8 * 2);
+    assert_eq!(core::mem::size_of::<InternalNode<i64, i64>>(), 16 + (CAPACITY * 3 + 1) * 8);
 }

library/alloc/src/collections/btree/set.rs

@@ -61,6 +61,7 @@ use super::Recover;
 /// ```
 #[derive(Hash, PartialEq, Eq, Ord, PartialOrd)]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(not(test), rustc_diagnostic_item = "BTreeSet")]
 pub struct BTreeSet<T> {
     map: BTreeMap<T, ()>,
 }

library/alloc/src/collections/linked_list.rs

@@ -35,6 +35,7 @@ mod tests;
 /// array-based containers are generally faster,
 /// more memory efficient, and make better use of CPU cache.
 #[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(not(test), rustc_diagnostic_item = "LinkedList")]
 pub struct LinkedList<T> {
     head: Option<NonNull<Node<T>>>,
     tail: Option<NonNull<Node<T>>>,

library/std/src/lazy.rs

@@ -177,7 +177,10 @@ impl<T> SyncOnceCell<T> {
 
     /// Sets the contents of this cell to `value`.
     ///
-    /// Returns `Ok(())` if the cell's value was updated.
+    /// May block if another thread is currently attempting to initialize the cell. The cell is
+    /// guaranteed to contain a value when set returns, though not necessarily the one provided.
+    ///
+    /// Returns `Ok(())` if the cell's value was set by this call.
     ///
     /// # Examples
     ///

library/std/src/sync/mpsc/mod.rs

@@ -310,6 +310,7 @@ mod cache_aligned;
 /// println!("{}", recv.recv().unwrap()); // Received after 2 seconds
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(not(test), rustc_diagnostic_item = "Receiver")]
 pub struct Receiver<T> {
     inner: UnsafeCell<Flavor<T>>,
 }

src/bootstrap/builder.rs

@@ -57,14 +57,6 @@ pub trait Step: 'static + Clone + Debug + PartialEq + Eq + Hash {
     /// `true` here can still be overwritten by `should_run` calling `default_condition`.
     const DEFAULT: bool = false;
 
-    /// Whether this step should be run even when `download-rustc` is set.
-    ///
-    /// Most steps are not important when the compiler is downloaded, since they will be included in
-    /// the pre-compiled sysroot. Steps can set this to `true` to be built anyway.
-    ///
-    /// When in doubt, set this to `false`.
-    const ENABLE_DOWNLOAD_RUSTC: bool = false;
-
     /// If true, then this rule should be skipped if --target was specified, but --host was not
     const ONLY_HOSTS: bool = false;
 
@@ -107,7 +99,6 @@ impl RunConfig<'_> {
 
 struct StepDescription {
     default: bool,
-    enable_download_rustc: bool,
     only_hosts: bool,
     should_run: fn(ShouldRun<'_>) -> ShouldRun<'_>,
     make_run: fn(RunConfig<'_>),
@@ -162,7 +153,6 @@ impl StepDescription {
     fn from<S: Step>() -> StepDescription {
         StepDescription {
             default: S::DEFAULT,
-            enable_download_rustc: S::ENABLE_DOWNLOAD_RUSTC,
             only_hosts: S::ONLY_HOSTS,
             should_run: S::should_run,
             make_run: S::make_run,
@@ -179,14 +169,6 @@ impl StepDescription {
                 "{:?} not skipped for {:?} -- not in {:?}",
                 pathset, self.name, builder.config.exclude
             );
-        } else if builder.config.download_rustc && !self.enable_download_rustc {
-            if !builder.config.dry_run {
-                eprintln!(
-                    "Not running {} because its artifacts have been downloaded from CI (`download-rustc` is set)",
-                    self.name
-                );
-            }
-            return;
         }
 
         // Determine the targets participating in this rule.

src/bootstrap/check.rs

@@ -62,7 +62,6 @@ fn cargo_subcommand(kind: Kind) -> &'static str {
 impl Step for Std {
     type Output = ();
     const DEFAULT: bool = true;
-    const ENABLE_DOWNLOAD_RUSTC: bool = true;
 
     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
         run.all_krates("test")
@@ -156,7 +155,6 @@ impl Step for Rustc {
     type Output = ();
     const ONLY_HOSTS: bool = true;
     const DEFAULT: bool = true;
-    const ENABLE_DOWNLOAD_RUSTC: bool = true;
 
     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
         run.all_krates("rustc-main")
@@ -235,7 +233,6 @@ impl Step for CodegenBackend {
     type Output = ();
     const ONLY_HOSTS: bool = true;
     const DEFAULT: bool = true;
-    const ENABLE_DOWNLOAD_RUSTC: bool = true;
 
     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
         run.paths(&["compiler/rustc_codegen_cranelift", "rustc_codegen_cranelift"])
@@ -293,7 +290,6 @@ macro_rules! tool_check_step {
             type Output = ();
             const ONLY_HOSTS: bool = true;
             const DEFAULT: bool = true;
-            const ENABLE_DOWNLOAD_RUSTC: bool = true;
 
             fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
                 run.path($path)

src/bootstrap/compile.rs

@@ -63,6 +63,12 @@ impl Step for Std {
         let target = self.target;
         let compiler = self.compiler;
 
+        // These artifacts were already copied (in `impl Step for Sysroot`).
+        // Don't recompile them.
+        if builder.config.download_rustc {
+            return;
+        }
+
         if builder.config.keep_stage.contains(&compiler.stage)
             || builder.config.keep_stage_std.contains(&compiler.stage)
         {
@@ -178,7 +184,9 @@ fn copy_self_contained_objects(
     // To do that we have to distribute musl startup objects as a part of Rust toolchain
     // and link with them manually in the self-contained mode.
     if target.contains("musl") {
-        let srcdir = builder.musl_libdir(target).unwrap();
+        let srcdir = builder.musl_libdir(target).unwrap_or_else(|| {
+            panic!("Target {:?} does not have a \"musl-libdir\" key", target.triple)
+        });
         for &obj in &["crt1.o", "Scrt1.o", "rcrt1.o", "crti.o", "crtn.o"] {
             copy_and_stamp(
                 builder,
@@ -196,7 +204,12 @@ fn copy_self_contained_objects(
             target_deps.push((target, DependencyType::TargetSelfContained));
         }
     } else if target.ends_with("-wasi") {
-        let srcdir = builder.wasi_root(target).unwrap().join("lib/wasm32-wasi");
+        let srcdir = builder
+            .wasi_root(target)
+            .unwrap_or_else(|| {
+                panic!("Target {:?} does not have a \"wasi-root\" key", target.triple)
+            })
+            .join("lib/wasm32-wasi");
         for &obj in &["crt1.o", "crt1-reactor.o"] {
             copy_and_stamp(
                 builder,
@@ -500,6 +513,13 @@ impl Step for Rustc {
         let compiler = self.compiler;
         let target = self.target;
 
+        if builder.config.download_rustc {
+            // Copy the existing artifacts instead of rebuilding them.
+            // NOTE: this path is only taken for tools linking to rustc-dev.
+            builder.ensure(Sysroot { compiler });
+            return;
+        }
+
         builder.ensure(Std { compiler, target });
 
         if builder.config.keep_stage.contains(&compiler.stage) {

src/bootstrap/tool.rs

@@ -483,7 +483,6 @@ pub struct Rustdoc {
 impl Step for Rustdoc {
     type Output = PathBuf;
     const DEFAULT: bool = true;
-    const ENABLE_DOWNLOAD_RUSTC: bool = true;
     const ONLY_HOSTS: bool = true;
 
     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {

src/test/ui/lint/renamed-lints-still-apply.rs

@@ -0,0 +1,9 @@
+// compile-flags: --crate-type lib
+#![deny(single_use_lifetime)]
+//~^ WARNING renamed
+//~| NOTE `#[warn(renamed_and_removed_lints)]` on by default
+//~| NOTE defined here
+fn _foo<'a>(_x: &'a u32) {}
+//~^ ERROR only used once
+//~| NOTE this lifetime
+//~| NOTE is used only here

src/test/ui/lint/renamed-lints-still-apply.stderr

@@ -0,0 +1,28 @@
+warning: lint `single_use_lifetime` has been renamed to `single_use_lifetimes`
+  --> $DIR/renamed-lints-still-apply.rs:2:9
+   |
+LL | #![deny(single_use_lifetime)]
+   |         ^^^^^^^^^^^^^^^^^^^ help: use the new name: `single_use_lifetimes`
+   |
+   = note: `#[warn(renamed_and_removed_lints)]` on by default
+
+error: lifetime parameter `'a` only used once
+  --> $DIR/renamed-lints-still-apply.rs:6:9
+   |
+LL | fn _foo<'a>(_x: &'a u32) {}
+   |         ^^       -- ...is used only here
+   |         |
+   |         this lifetime...
+   |
+note: the lint level is defined here
+  --> $DIR/renamed-lints-still-apply.rs:2:9
+   |
+LL | #![deny(single_use_lifetime)]
+   |         ^^^^^^^^^^^^^^^^^^^
+help: elide the single-use lifetime
+   |
+LL | fn _foo(_x: &u32) {}
+   |       --    --
+
+error: aborting due to previous error; 1 warning emitted
+

src/tools/clippy/clippy_lints/src/entry.rs

@@ -9,6 +9,7 @@ use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::hir::map::Map;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
+use rustc_span::sym;
 
 declare_clippy_lint! {
     /// **What it does:** Checks for uses of `contains_key` + `insert` on `HashMap`
@@ -111,7 +112,7 @@ fn check_cond<'a>(cx: &LateContext<'_>, check: &'a Expr<'a>) -> Option<(&'static
             return if match_type(cx, obj_ty, &paths::BTREEMAP) {
                 Some(("BTreeMap", map, key))
             }
-            else if is_type_diagnostic_item(cx, obj_ty, sym!(hashmap_type)) {
+            else if is_type_diagnostic_item(cx, obj_ty, sym::hashmap_type) {
                 Some(("HashMap", map, key))
             }
             else {

src/tools/clippy/clippy_lints/src/loops.rs

@@ -1010,7 +1010,7 @@ fn is_slice_like<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'_>) -> bool {
         _ => false,
     };
 
-    is_slice || is_type_diagnostic_item(cx, ty, sym::vec_type) || is_type_diagnostic_item(cx, ty, sym!(vecdeque_type))
+    is_slice || is_type_diagnostic_item(cx, ty, sym::vec_type) || is_type_diagnostic_item(cx, ty, sym::vecdeque_type)
 }
 
 fn fetch_cloned_expr<'tcx>(expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
@@ -1908,7 +1908,7 @@ fn check_for_loop_over_map_kv<'tcx>(
                 _ => arg,
             };
 
-            if is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) || match_type(cx, ty, &paths::BTREEMAP) {
+            if is_type_diagnostic_item(cx, ty, sym::hashmap_type) || match_type(cx, ty, &paths::BTREEMAP) {
                 span_lint_and_then(
                     cx,
                     FOR_KV_MAP,
@@ -2386,9 +2386,9 @@ fn is_ref_iterable_type(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
     is_iterable_array(ty, cx) ||
     is_type_diagnostic_item(cx, ty, sym::vec_type) ||
     match_type(cx, ty, &paths::LINKED_LIST) ||
-    is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) ||
+    is_type_diagnostic_item(cx, ty, sym::hashmap_type) ||
-    is_type_diagnostic_item(cx, ty, sym!(hashset_type)) ||
+    is_type_diagnostic_item(cx, ty, sym::hashset_type) ||
-    is_type_diagnostic_item(cx, ty, sym!(vecdeque_type)) ||
+    is_type_diagnostic_item(cx, ty, sym::vecdeque_type) ||
     match_type(cx, ty, &paths::BINARY_HEAP) ||
     match_type(cx, ty, &paths::BTREEMAP) ||
     match_type(cx, ty, &paths::BTREESET)
@@ -2922,9 +2922,9 @@ fn check_needless_collect_direct_usage<'tcx>(expr: &'tcx Expr<'_>, cx: &LateCont
         then {
             let ty = cx.typeck_results().node_type(ty.hir_id);
             if is_type_diagnostic_item(cx, ty, sym::vec_type) ||
-                is_type_diagnostic_item(cx, ty, sym!(vecdeque_type)) ||
+                is_type_diagnostic_item(cx, ty, sym::vecdeque_type) ||
                 match_type(cx, ty, &paths::BTREEMAP) ||
-                is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) {
+                is_type_diagnostic_item(cx, ty, sym::hashmap_type) {
                 if method.ident.name == sym!(len) {
                     let span = shorten_needless_collect_span(expr);
                     span_lint_and_sugg(
@@ -2992,7 +2992,7 @@ fn check_needless_collect_indirect_usage<'tcx>(expr: &'tcx Expr<'_>, cx: &LateCo
                 if let Some(GenericArg::Type(ref ty)) = generic_args.args.get(0);
                 if let ty = cx.typeck_results().node_type(ty.hir_id);
                 if is_type_diagnostic_item(cx, ty, sym::vec_type) ||
-                    is_type_diagnostic_item(cx, ty, sym!(vecdeque_type)) ||
+                    is_type_diagnostic_item(cx, ty, sym::vecdeque_type) ||
                     match_type(cx, ty, &paths::LINKED_LIST);
                 if let Some(iter_calls) = detect_iter_and_into_iters(block, *ident);
                 if iter_calls.len() == 1;

src/tools/clippy/clippy_lints/src/methods/mod.rs

@@ -24,7 +24,7 @@ use rustc_middle::ty::{self, TraitRef, Ty, TyS};
 use rustc_semver::RustcVersion;
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::Span;
-use rustc_span::symbol::{sym, SymbolStr};
+use rustc_span::symbol::{sym, Symbol, SymbolStr};
 use rustc_typeck::hir_ty_to_ty;
 
 use crate::consts::{constant, Constant};
@@ -2598,7 +2598,7 @@ fn lint_iter_nth<'tcx>(
         "slice"
     } else if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&iter_args[0]), sym::vec_type) {
         "Vec"
-    } else if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&iter_args[0]), sym!(vecdeque_type)) {
+    } else if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&iter_args[0]), sym::vecdeque_type) {
         "VecDeque"
     } else {
         let nth_args = nth_and_iter_args[0];
@@ -2652,10 +2652,10 @@ fn lint_get_unwrap<'tcx>(cx: &LateContext<'tcx>, expr: &hir::Expr<'_>, get_args:
     } else if is_type_diagnostic_item(cx, expr_ty, sym::vec_type) {
         needs_ref = get_args_str.parse::<usize>().is_ok();
         "Vec"
-    } else if is_type_diagnostic_item(cx, expr_ty, sym!(vecdeque_type)) {
+    } else if is_type_diagnostic_item(cx, expr_ty, sym::vecdeque_type) {
         needs_ref = get_args_str.parse::<usize>().is_ok();
         "VecDeque"
-    } else if !is_mut && is_type_diagnostic_item(cx, expr_ty, sym!(hashmap_type)) {
+    } else if !is_mut && is_type_diagnostic_item(cx, expr_ty, sym::hashmap_type) {
         needs_ref = true;
         "HashMap"
     } else if !is_mut && match_type(cx, expr_ty, &paths::BTREEMAP) {
@@ -3619,7 +3619,7 @@ fn lint_asref(cx: &LateContext<'_>, expr: &hir::Expr<'_>, call_name: &str, as_re
     }
 }
 
-fn ty_has_iter_method(cx: &LateContext<'_>, self_ref_ty: Ty<'_>) -> Option<(&'static str, &'static str)> {
+fn ty_has_iter_method(cx: &LateContext<'_>, self_ref_ty: Ty<'_>) -> Option<(Symbol, &'static str)> {
     has_iter_method(cx, self_ref_ty).map(|ty_name| {
         let mutbl = match self_ref_ty.kind() {
             ty::Ref(_, _, mutbl) => mutbl,

src/tools/clippy/clippy_lints/src/swap.rs

@@ -199,7 +199,7 @@ fn check_for_slice<'a>(cx: &LateContext<'_>, lhs1: &'a Expr<'_>, lhs2: &'a Expr<
                 if matches!(ty.kind(), ty::Slice(_))
                     || matches!(ty.kind(), ty::Array(_, _))
                     || is_type_diagnostic_item(cx, ty, sym::vec_type)
-                    || is_type_diagnostic_item(cx, ty, sym!(vecdeque_type))
+                    || is_type_diagnostic_item(cx, ty, sym::vecdeque_type)
                 {
                     return Slice::Swappable(lhs1, idx1, idx2);
                 }

src/tools/clippy/clippy_lints/src/types.rs

@@ -2680,14 +2680,14 @@ impl<'tcx> ImplicitHasherType<'tcx> {
 
             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
 
-            if is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) && params_len == 2 {
+            if is_type_diagnostic_item(cx, ty, sym::hashmap_type) && params_len == 2 {
                 Some(ImplicitHasherType::HashMap(
                     hir_ty.span,
                     ty,
                     snippet(cx, params[0].span, "K"),
                     snippet(cx, params[1].span, "V"),
                 ))
-            } else if is_type_diagnostic_item(cx, ty, sym!(hashset_type)) && params_len == 1 {
+            } else if is_type_diagnostic_item(cx, ty, sym::hashset_type) && params_len == 1 {
                 Some(ImplicitHasherType::HashSet(
                     hir_ty.span,
                     ty,

src/tools/clippy/clippy_lints/src/zero_sized_map_values.rs

@@ -5,6 +5,7 @@ use rustc_middle::ty::{Adt, Ty};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_target::abi::LayoutOf as _;
 use rustc_typeck::hir_ty_to_ty;
+use rustc_span::sym;
 
 use crate::utils::{is_normalizable, is_type_diagnostic_item, match_type, paths, span_lint_and_help};
 
@@ -47,7 +48,7 @@ impl LateLintPass<'_> for ZeroSizedMapValues {
             if !hir_ty.span.from_expansion();
             if !in_trait_impl(cx, hir_ty.hir_id);
             let ty = ty_from_hir_ty(cx, hir_ty);
-            if is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) || match_type(cx, ty, &paths::BTREEMAP);
+            if is_type_diagnostic_item(cx, ty, sym::hashmap_type) || match_type(cx, ty, &paths::BTREEMAP);
             if let Adt(_, ref substs) = ty.kind();
             let ty = substs.type_at(1);
             // Do this to prevent `layout_of` crashing, being unable to fully normalize `ty`.

src/tools/clippy/clippy_utils/src/eager_or_lazy.rs

@@ -18,6 +18,7 @@ use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
 use rustc_hir::{Block, Expr, ExprKind, Path, QPath};
 use rustc_lint::LateContext;
 use rustc_middle::hir::map::Map;
+use rustc_span::sym;
 
 /// Is the expr pure (is it free from side-effects)?
 /// This function is named so to stress that it isn't exhaustive and returns FNs.
@@ -99,7 +100,7 @@ fn identify_some_potentially_expensive_patterns<'tcx>(cx: &LateContext<'tcx>, ex
                 ExprKind::Call(..) => !is_ctor_or_promotable_const_function(self.cx, expr),
                 ExprKind::Index(obj, _) => {
                     let ty = self.cx.typeck_results().expr_ty(obj);
-                    is_type_diagnostic_item(self.cx, ty, sym!(hashmap_type))
+                    is_type_diagnostic_item(self.cx, ty, sym::hashmap_type)
                         || match_type(self.cx, ty, &paths::BTREEMAP)
                 },
                 ExprKind::MethodCall(..) => true,

src/tools/clippy/clippy_utils/src/lib.rs

@@ -1295,24 +1295,24 @@ pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool
 }
 
 /// Returns true if ty has `iter` or `iter_mut` methods
-pub fn has_iter_method(cx: &LateContext<'_>, probably_ref_ty: Ty<'_>) -> Option<&'static str> {
+pub fn has_iter_method(cx: &LateContext<'_>, probably_ref_ty: Ty<'_>) -> Option<Symbol> {
     // FIXME: instead of this hard-coded list, we should check if `<adt>::iter`
     // exists and has the desired signature. Unfortunately FnCtxt is not exported
     // so we can't use its `lookup_method` method.
-    let into_iter_collections: [&[&str]; 13] = [
+    let into_iter_collections: &[Symbol] = &[
-        &paths::VEC,
+        sym::vec_type,
-        &paths::OPTION,
+        sym::option_type,
-        &paths::RESULT,
+        sym::result_type,
-        &paths::BTREESET,
+        sym::BTreeMap,
-        &paths::BTREEMAP,
+        sym::BTreeSet,
-        &paths::VEC_DEQUE,
+        sym::vecdeque_type,
-        &paths::LINKED_LIST,
+        sym::LinkedList,
-        &paths::BINARY_HEAP,
+        sym::BinaryHeap,
-        &paths::HASHSET,
+        sym::hashset_type,
-        &paths::HASHMAP,
+        sym::hashmap_type,
-        &paths::PATH_BUF,
+        sym::PathBuf,
-        &paths::PATH,
+        sym::Path,
-        &paths::RECEIVER,
+        sym::Receiver,
     ];
 
     let ty_to_check = match probably_ref_ty.kind() {
@@ -1321,15 +1321,15 @@ pub fn has_iter_method(cx: &LateContext<'_>, probably_ref_ty: Ty<'_>) -> Option<
     };
 
     let def_id = match ty_to_check.kind() {
-        ty::Array(..) => return Some("array"),
+        ty::Array(..) => return Some(sym::array),
-        ty::Slice(..) => return Some("slice"),
+        ty::Slice(..) => return Some(sym::slice),
         ty::Adt(adt, _) => adt.did,
         _ => return None,
     };
 
-    for path in &into_iter_collections {
+    for &name in into_iter_collections {
-        if match_def_path(cx, def_id, path) {
+        if cx.tcx.is_diagnostic_item(name, def_id) {
-            return Some(*path.last().unwrap());
+            return Some(cx.tcx.item_name(def_id));
         }
     }
     None

src/tools/clippy/clippy_utils/src/paths.rs

@@ -99,7 +99,6 @@ pub(super) const PANIC_ANY: [&str; 3] = ["std", "panic", "panic_any"];
 pub const PARKING_LOT_MUTEX_GUARD: [&str; 2] = ["parking_lot", "MutexGuard"];
 pub const PARKING_LOT_RWLOCK_READ_GUARD: [&str; 2] = ["parking_lot", "RwLockReadGuard"];
 pub const PARKING_LOT_RWLOCK_WRITE_GUARD: [&str; 2] = ["parking_lot", "RwLockWriteGuard"];
-pub const PATH: [&str; 3] = ["std", "path", "Path"];
 pub const PATH_BUF: [&str; 3] = ["std", "path", "PathBuf"];
 pub const PATH_BUF_AS_PATH: [&str; 4] = ["std", "path", "PathBuf", "as_path"];
 pub const PATH_TO_PATH_BUF: [&str; 4] = ["std", "path", "Path", "to_path_buf"];
@@ -116,7 +115,6 @@ pub const PUSH_STR: [&str; 4] = ["alloc", "string", "String", "push_str"];
 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"];