[Clippy] Swap manual_retain to use diagnostic items instead of paths

compiler/rustc_span/src/symbol.rs

@@ -488,6 +488,7 @@ symbols! {
         begin_panic,
         bench,
         bin,
+        binaryheap_iter,
         bind_by_move_pattern_guards,
         bindings_after_at,
         bitand,
@@ -511,6 +512,7 @@ symbols! {
         breakpoint,
         bridge,
         bswap,
+        btreeset_iter,
         builtin_syntax,
         c,
         c_str,
@@ -971,6 +973,7 @@ symbols! {
         half_open_range_patterns,
         half_open_range_patterns_in_slices,
         hash,
+        hashset_iter,
         hexagon_target_feature,
         hidden,
         homogeneous_aggregate,
@@ -1077,6 +1080,9 @@ symbols! {
         item,
         item_like_imports,
         iter,
+        iter_cloned,
+        iter_copied,
+        iter_filter,
         iter_mut,
         iter_repeat,
         iterator,
@@ -1817,6 +1823,7 @@ symbols! {
         slice,
         slice_from_raw_parts,
         slice_from_raw_parts_mut,
+        slice_iter,
         slice_len_fn,
         slice_patterns,
         slicing_syntax,
@@ -1849,6 +1856,7 @@ symbols! {
         stop_after_dataflow,
         store,
         str,
+        str_chars,
         str_from_utf8,
         str_from_utf8_mut,
         str_from_utf8_unchecked,
@@ -2064,6 +2072,7 @@ symbols! {
         variant_count,
         vec,
         vec_macro,
+        vecdeque_iter,
         version,
         vfp2,
         vis,

library/alloc/src/collections/binary_heap/mod.rs

@@ -959,6 +959,7 @@ impl<T, A: Allocator> BinaryHeap<T, A> {
     /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[cfg_attr(not(test), rustc_diagnostic_item = "binaryheap_iter")]
     pub fn iter(&self) -> Iter<'_, T> {
         Iter { iter: self.data.iter() }
     }

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

@@ -1132,6 +1132,7 @@ impl<T, A: Allocator + Clone> BTreeSet<T, A> {
     /// assert_eq!(set_iter.next(), None);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[cfg_attr(not(test), rustc_diagnostic_item = "btreeset_iter")]
     pub fn iter(&self) -> Iter<'_, T> {
         Iter { iter: self.map.keys() }
     }

library/alloc/src/collections/vec_deque/mod.rs

@@ -1201,6 +1201,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// assert_eq!(&c[..], b);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[cfg_attr(not(test), rustc_diagnostic_item = "vecdeque_iter")]
     pub fn iter(&self) -> Iter<'_, T> {
         let (a, b) = self.as_slices();
         Iter::new(a.iter(), b.iter())

library/core/src/iter/traits/iterator.rs

@@ -876,6 +876,7 @@ pub trait Iterator {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_do_not_const_check]
+    #[cfg_attr(not(test), rustc_diagnostic_item = "iter_filter")]
     fn filter<P>(self, predicate: P) -> Filter<Self, P>
     where
         Self: Sized,
@@ -3412,6 +3413,7 @@ pub trait Iterator {
     /// ```
     #[stable(feature = "iter_copied", since = "1.36.0")]
     #[rustc_do_not_const_check]
+    #[cfg_attr(not(test), rustc_diagnostic_item = "iter_copied")]
     fn copied<'a, T: 'a>(self) -> Copied<Self>
     where
         Self: Sized + Iterator<Item = &'a T>,
@@ -3460,6 +3462,7 @@ pub trait Iterator {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_do_not_const_check]
+    #[cfg_attr(not(test), rustc_diagnostic_item = "iter_cloned")]
     fn cloned<'a, T: 'a>(self) -> Cloned<Self>
     where
         Self: Sized + Iterator<Item = &'a T>,

library/core/src/slice/mod.rs

@@ -1010,6 +1010,7 @@ impl<T> [T] {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
+    #[cfg_attr(not(test), rustc_diagnostic_item = "slice_iter")]
     pub fn iter(&self) -> Iter<'_, T> {
         Iter::new(self)
     }

library/core/src/str/mod.rs

@@ -832,6 +832,7 @@ impl str {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
+    #[cfg_attr(not(test), rustc_diagnostic_item = "str_chars")]
     pub fn chars(&self) -> Chars<'_> {
         Chars { iter: self.as_bytes().iter() }
     }

library/std/src/collections/hash/set.rs

@@ -187,6 +187,7 @@ impl<T, S> HashSet<T, S> {
     #[inline]
     #[rustc_lint_query_instability]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[cfg_attr(not(test), rustc_diagnostic_item = "hashset_iter")]
     pub fn iter(&self) -> Iter<'_, T> {
         Iter { base: self.base.iter() }
     }

src/tools/clippy/clippy_lints/src/manual_retain.rs

@@ -3,22 +3,22 @@ use clippy_config::Conf;
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet;
 use clippy_utils::ty::{get_type_diagnostic_name, is_type_lang_item};
-use clippy_utils::{match_def_path, paths, SpanlessEq};
+use clippy_utils::SpanlessEq;
 use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_hir::ExprKind::Assign;
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::impl_lint_pass;
-use rustc_span::symbol::sym;
+use rustc_span::symbol::{sym, Symbol};
 use rustc_span::Span;
 
-const ACCEPTABLE_METHODS: [&[&str]; 5] = [
-    &paths::BINARYHEAP_ITER,
-    &paths::HASHSET_ITER,
-    &paths::BTREESET_ITER,
-    &paths::SLICE_INTO,
-    &paths::VEC_DEQUE_ITER,
+const ACCEPTABLE_METHODS: [Symbol; 5] = [
+    sym::binaryheap_iter,
+    sym::hashset_iter,
+    sym::btreeset_iter,
+    sym::slice_iter,
+    sym::vecdeque_iter,
 ];
 
 declare_clippy_lint! {
@@ -84,7 +84,7 @@ fn check_into_iter(
 ) {
     if let hir::ExprKind::MethodCall(_, into_iter_expr, [_], _) = &target_expr.kind
         && let Some(filter_def_id) = cx.typeck_results().type_dependent_def_id(target_expr.hir_id)
-        && match_def_path(cx, filter_def_id, &paths::CORE_ITER_FILTER)
+        && cx.tcx.is_diagnostic_item(sym::iter_filter, filter_def_id)
         && let hir::ExprKind::MethodCall(_, struct_expr, [], _) = &into_iter_expr.kind
         && let Some(into_iter_def_id) = cx.typeck_results().type_dependent_def_id(into_iter_expr.hir_id)
         && Some(into_iter_def_id) == cx.tcx.lang_items().into_iter_fn()
@@ -127,14 +127,14 @@ fn check_iter(
 ) {
     if let hir::ExprKind::MethodCall(_, filter_expr, [], _) = &target_expr.kind
         && let Some(copied_def_id) = cx.typeck_results().type_dependent_def_id(target_expr.hir_id)
-        && (match_def_path(cx, copied_def_id, &paths::CORE_ITER_COPIED)
-            || match_def_path(cx, copied_def_id, &paths::CORE_ITER_CLONED))
+        && (cx.tcx.is_diagnostic_item(sym::iter_copied, copied_def_id)
+            || cx.tcx.is_diagnostic_item(sym::iter_cloned, copied_def_id))
         && let hir::ExprKind::MethodCall(_, iter_expr, [_], _) = &filter_expr.kind
         && let Some(filter_def_id) = cx.typeck_results().type_dependent_def_id(filter_expr.hir_id)
-        && match_def_path(cx, filter_def_id, &paths::CORE_ITER_FILTER)
+        && cx.tcx.is_diagnostic_item(sym::iter_filter, filter_def_id)
         && let hir::ExprKind::MethodCall(_, struct_expr, [], _) = &iter_expr.kind
         && let Some(iter_expr_def_id) = cx.typeck_results().type_dependent_def_id(iter_expr.hir_id)
-        && match_acceptable_def_path(cx, iter_expr_def_id)
+        && match_acceptable_sym(cx, iter_expr_def_id)
         && match_acceptable_type(cx, left_expr, msrv)
         && SpanlessEq::new(cx).eq_expr(left_expr, struct_expr)
         && let hir::ExprKind::MethodCall(_, _, [closure_expr], _) = filter_expr.kind
@@ -189,10 +189,10 @@ fn check_to_owned(
         && cx.tcx.is_diagnostic_item(sym::to_owned_method, to_owned_def_id)
         && let hir::ExprKind::MethodCall(_, chars_expr, [_], _) = &filter_expr.kind
         && let Some(filter_def_id) = cx.typeck_results().type_dependent_def_id(filter_expr.hir_id)
-        && match_def_path(cx, filter_def_id, &paths::CORE_ITER_FILTER)
+        && cx.tcx.is_diagnostic_item(sym::iter_filter, filter_def_id)
         && let hir::ExprKind::MethodCall(_, str_expr, [], _) = &chars_expr.kind
         && let Some(chars_expr_def_id) = cx.typeck_results().type_dependent_def_id(chars_expr.hir_id)
-        && match_def_path(cx, chars_expr_def_id, &paths::STR_CHARS)
+        && cx.tcx.is_diagnostic_item(sym::str_chars, chars_expr_def_id)
         && let ty = cx.typeck_results().expr_ty(str_expr).peel_refs()
         && is_type_lang_item(cx, ty, hir::LangItem::String)
         && SpanlessEq::new(cx).eq_expr(left_expr, str_expr)
@@ -247,10 +247,10 @@ fn make_sugg(
     }
 }
 
-fn match_acceptable_def_path(cx: &LateContext<'_>, collect_def_id: DefId) -> bool {
+fn match_acceptable_sym(cx: &LateContext<'_>, collect_def_id: DefId) -> bool {
     ACCEPTABLE_METHODS
         .iter()
-        .any(|&method| match_def_path(cx, collect_def_id, method))
+        .any(|&method| cx.tcx.is_diagnostic_item(method, collect_def_id))
 }
 
 fn match_acceptable_type(cx: &LateContext<'_>, expr: &hir::Expr<'_>, msrv: &Msrv) -> bool {

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

@@ -12,13 +12,8 @@ pub const APPLICABILITY_VALUES: [[&str; 3]; 4] = [
     ["rustc_lint_defs", "Applicability", "MachineApplicable"],
 ];
 pub const DIAG: [&str; 2] = ["rustc_errors", "Diag"];
-pub const BINARYHEAP_ITER: [&str; 5] = ["alloc", "collections", "binary_heap", "BinaryHeap", "iter"];
 pub const BTREEMAP_CONTAINS_KEY: [&str; 6] = ["alloc", "collections", "btree", "map", "BTreeMap", "contains_key"];
 pub const BTREEMAP_INSERT: [&str; 6] = ["alloc", "collections", "btree", "map", "BTreeMap", "insert"];
-pub const BTREESET_ITER: [&str; 6] = ["alloc", "collections", "btree", "set", "BTreeSet", "iter"];
-pub const CORE_ITER_CLONED: [&str; 6] = ["core", "iter", "traits", "iterator", "Iterator", "cloned"];
-pub const CORE_ITER_COPIED: [&str; 6] = ["core", "iter", "traits", "iterator", "Iterator", "copied"];
-pub const CORE_ITER_FILTER: [&str; 6] = ["core", "iter", "traits", "iterator", "Iterator", "filter"];
 pub const CORE_RESULT_OK_METHOD: [&str; 4] = ["core", "result", "Result", "ok"];
 pub const CSTRING_AS_C_STR: [&str; 5] = ["alloc", "ffi", "c_str", "CString", "as_c_str"];
 pub const EARLY_CONTEXT: [&str; 2] = ["rustc_lint", "EarlyContext"];
@@ -39,7 +34,6 @@ pub const HASHMAP_VALUES: [&str; 5] = ["std", "collections", "hash", "map", "Val
 pub const HASHMAP_DRAIN: [&str; 5] = ["std", "collections", "hash", "map", "Drain"];
 pub const HASHMAP_VALUES_MUT: [&str; 5] = ["std", "collections", "hash", "map", "ValuesMut"];
 pub const HASHSET_ITER_TY: [&str; 5] = ["std", "collections", "hash", "set", "Iter"];
-pub const HASHSET_ITER: [&str; 6] = ["std", "collections", "hash", "set", "HashSet", "iter"];
 pub const HASHSET_DRAIN: [&str; 5] = ["std", "collections", "hash", "set", "Drain"];
 pub const IDENT: [&str; 3] = ["rustc_span", "symbol", "Ident"];
 pub const IDENT_AS_STR: [&str; 4] = ["rustc_span", "symbol", "Ident", "as_str"];
@@ -71,13 +65,11 @@ pub const REGEX_SET_NEW: [&str; 3] = ["regex", "RegexSet", "new"];
 pub const SERDE_DESERIALIZE: [&str; 3] = ["serde", "de", "Deserialize"];
 pub const SERDE_DE_VISITOR: [&str; 3] = ["serde", "de", "Visitor"];
 pub const SLICE_INTO_VEC: [&str; 4] = ["alloc", "slice", "<impl [T]>", "into_vec"];
-pub const SLICE_INTO: [&str; 4] = ["core", "slice", "<impl [T]>", "iter"];
 pub const STD_IO_SEEK_FROM_CURRENT: [&str; 4] = ["std", "io", "SeekFrom", "Current"];
 pub const STD_IO_SEEKFROM_START: [&str; 4] = ["std", "io", "SeekFrom", "Start"];
 pub const STRING_AS_MUT_STR: [&str; 4] = ["alloc", "string", "String", "as_mut_str"];
 pub const STRING_AS_STR: [&str; 4] = ["alloc", "string", "String", "as_str"];
 pub const STRING_NEW: [&str; 4] = ["alloc", "string", "String", "new"];
-pub const STR_CHARS: [&str; 4] = ["core", "str", "<impl str>", "chars"];
 pub const STR_ENDS_WITH: [&str; 4] = ["core", "str", "<impl str>", "ends_with"];
 pub const STR_LEN: [&str; 4] = ["core", "str", "<impl str>", "len"];
 pub const STR_STARTS_WITH: [&str; 4] = ["core", "str", "<impl str>", "starts_with"];
@@ -100,7 +92,6 @@ pub const TOKIO_IO_OPEN_OPTIONS: [&str; 4] = ["tokio", "fs", "open_options", "Op
 pub const TOKIO_IO_OPEN_OPTIONS_NEW: [&str; 5] = ["tokio", "fs", "open_options", "OpenOptions", "new"];
 pub const VEC_AS_MUT_SLICE: [&str; 4] = ["alloc", "vec", "Vec", "as_mut_slice"];
 pub const VEC_AS_SLICE: [&str; 4] = ["alloc", "vec", "Vec", "as_slice"];
-pub const VEC_DEQUE_ITER: [&str; 5] = ["alloc", "collections", "vec_deque", "VecDeque", "iter"];
 pub const VEC_FROM_ELEM: [&str; 3] = ["alloc", "vec", "from_elem"];
 pub const VEC_NEW: [&str; 4] = ["alloc", "vec", "Vec", "new"];
 pub const VEC_WITH_CAPACITY: [&str; 4] = ["alloc", "vec", "Vec", "with_capacity"];