Auto merge of #95562 - lcnr:attr-no-encode, r=davidtwco

don't encode only locally used attrs

Part of https://github.com/rust-lang/compiler-team/issues/505.

We now filter builtin attributes before encoding them in the crate metadata in case they should only be used in the local crate. To prevent accidental misuse `get_attrs` now requires the caller to state which attribute they are interested in. For places where that isn't trivially possible, I've added a method `fn get_attrs_unchecked` which I intend to remove in a followup PR.

After this pull request landed, we can then slowly move all attributes to only be used in the local crate while being certain that we don't accidentally try to access them from extern crates.

cc https://github.com/rust-lang/rust/pull/94963#issuecomment-1082924289

16 files changed, 54 insertions, 68 deletions

diff --git a/src/librustdoc/clean/inline.rs b/src/librustdoc/clean/inline.rs
index 261eb39bf72..9a579cb5311 100644
--- a/src/librustdoc/clean/inline.rs
+++ b/src/librustdoc/clean/inline.rs
@@ -22,7 +22,7 @@ use crate::clean::{
 use crate::core::DocContext;
 use crate::formats::item_type::ItemType;
 
-type Attrs<'hir> = rustc_middle::ty::Attributes<'hir>;
+type Attrs<'hir> = &'hir [ast::Attribute];
 
 /// Attempt to inline a definition into this AST.
 ///
@@ -155,7 +155,7 @@ crate fn try_inline_glob(
 }
 
 crate fn load_attrs<'hir>(cx: &DocContext<'hir>, did: DefId) -> Attrs<'hir> {
-    cx.tcx.get_attrs(did)
+    cx.tcx.get_attrs_unchecked(did)
 }
 
 /// Record an external fully qualified name in the external_paths cache.
@@ -691,7 +691,7 @@ crate fn record_extern_trait(cx: &mut DocContext<'_>, did: DefId) {
 
     let trait_ = clean::TraitWithExtraInfo {
         trait_,
-        is_notable: clean::utils::has_doc_flag(cx.tcx.get_attrs(did), sym::notable_trait),
+        is_notable: clean::utils::has_doc_flag(cx.tcx, did, sym::notable_trait),
     };
     cx.external_traits.borrow_mut().insert(did, trait_);
     cx.active_extern_traits.remove(&did);
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 2b65b8f910c..456d860f125 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -211,8 +211,8 @@ impl ExternalCrate {
         // Failing that, see if there's an attribute specifying where to find this
         // external crate
         let did = self.crate_num.as_def_id();
-        tcx.get_attrs(did)
-            .lists(sym::doc)
+        tcx.get_attrs(did, sym::doc)
+            .flat_map(|attr| attr.meta_item_list().unwrap_or_default())
             .filter(|a| a.has_name(sym::html_root_url))
             .filter_map(|a| a.value_str())
             .map(to_remote)
@@ -226,11 +226,13 @@ impl ExternalCrate {
 
         let as_keyword = |res: Res<!>| {
             if let Res::Def(DefKind::Mod, def_id) = res {
-                let attrs = tcx.get_attrs(def_id);
                 let mut keyword = None;
-                for attr in attrs.lists(sym::doc) {
-                    if attr.has_name(sym::keyword) {
-                        if let Some(v) = attr.value_str() {
+                let meta_items = tcx
+                    .get_attrs(def_id, sym::doc)
+                    .flat_map(|attr| attr.meta_item_list().unwrap_or_default());
+                for meta in meta_items {
+                    if meta.has_name(sym::keyword) {
+                        if let Some(v) = meta.value_str() {
                             keyword = Some(v);
                             break;
                         }
@@ -288,11 +290,13 @@ impl ExternalCrate {
         // rendering by delegating everything to a hash map.
         let as_primitive = |res: Res<!>| {
             if let Res::Def(DefKind::Mod, def_id) = res {
-                let attrs = tcx.get_attrs(def_id);
                 let mut prim = None;
-                for attr in attrs.lists(sym::doc) {
-                    if let Some(v) = attr.value_str() {
-                        if attr.has_name(sym::primitive) {
+                let meta_items = tcx
+                    .get_attrs(def_id, sym::doc)
+                    .flat_map(|attr| attr.meta_item_list().unwrap_or_default());
+                for meta in meta_items {
+                    if let Some(v) = meta.value_str() {
+                        if meta.has_name(sym::primitive) {
                             prim = PrimitiveType::from_symbol(v);
                             if prim.is_some() {
                                 break;
@@ -413,7 +417,10 @@ impl Item {
     }
 
     crate fn inner_docs(&self, tcx: TyCtxt<'_>) -> bool {
-        self.item_id.as_def_id().map(|did| tcx.get_attrs(did).inner_docs()).unwrap_or(false)
+        self.item_id
+            .as_def_id()
+            .map(|did| tcx.get_attrs_unchecked(did).inner_docs())
+            .unwrap_or(false)
     }
 
     crate fn span(&self, tcx: TyCtxt<'_>) -> Span {
@@ -464,7 +471,7 @@ impl Item {
         kind: ItemKind,
         cx: &mut DocContext<'_>,
     ) -> Item {
-        let ast_attrs = cx.tcx.get_attrs(def_id);
+        let ast_attrs = cx.tcx.get_attrs_unchecked(def_id);
 
         Self::from_def_id_and_attrs_and_parts(
             def_id,
diff --git a/src/librustdoc/clean/utils.rs b/src/librustdoc/clean/utils.rs
index 3a2f24d719c..c67b92df643 100644
--- a/src/librustdoc/clean/utils.rs
+++ b/src/librustdoc/clean/utils.rs
@@ -474,10 +474,9 @@ crate fn find_nearest_parent_module(tcx: TyCtxt<'_>, def_id: DefId) -> Option<De
 ///
 /// This function exists because it runs on `hir::Attributes` whereas the other is a
 /// `clean::Attributes` method.
-crate fn has_doc_flag(attrs: ty::Attributes<'_>, flag: Symbol) -> bool {
-    attrs.iter().any(|attr| {
-        attr.has_name(sym::doc)
-            && attr.meta_item_list().map_or(false, |l| rustc_attr::list_contains_name(&l, flag))
+crate fn has_doc_flag(tcx: TyCtxt<'_>, did: DefId, flag: Symbol) -> bool {
+    tcx.get_attrs(did, sym::doc).any(|attr| {
+        attr.meta_item_list().map_or(false, |l| rustc_attr::list_contains_name(&l, flag))
     })
 }
 
diff --git a/src/librustdoc/html/render/print_item.rs b/src/librustdoc/html/render/print_item.rs
index fbb3d3e4584..4951cd83af2 100644
--- a/src/librustdoc/html/render/print_item.rs
+++ b/src/librustdoc/html/render/print_item.rs
@@ -323,7 +323,7 @@ fn item_module(w: &mut Buffer, cx: &Context<'_>, item: &clean::Item, items: &[cl
 
             clean::ImportItem(ref import) => {
                 let (stab, stab_tags) = if let Some(import_def_id) = import.source.did {
-                    let ast_attrs = cx.tcx().get_attrs(import_def_id);
+                    let ast_attrs = cx.tcx().get_attrs_unchecked(import_def_id);
                     let import_attrs = Box::new(clean::Attributes::from_ast(ast_attrs, None));
 
                     // Just need an item with the correct def_id and attrs
diff --git a/src/librustdoc/passes/collect_trait_impls.rs b/src/librustdoc/passes/collect_trait_impls.rs
index d245c3750ec..3b7ca7dc3c5 100644
--- a/src/librustdoc/passes/collect_trait_impls.rs
+++ b/src/librustdoc/passes/collect_trait_impls.rs
@@ -53,9 +53,7 @@ crate fn collect_trait_impls(mut krate: Crate, cx: &mut DocContext<'_>) -> Crate
             while let Some(did) = parent {
                 attr_buf.extend(
                     cx.tcx
-                        .get_attrs(did)
-                        .iter()
-                        .filter(|attr| attr.has_name(sym::doc))
+                        .get_attrs(did, sym::doc)
                         .filter(|attr| {
                             if let Some([attr]) = attr.meta_item_list().as_deref() {
                                 attr.has_name(sym::cfg)
diff --git a/src/tools/clippy/clippy_lints/src/derivable_impls.rs b/src/tools/clippy/clippy_lints/src/derivable_impls.rs
index 14098340745..34a5f8444de 100644
--- a/src/tools/clippy/clippy_lints/src/derivable_impls.rs
+++ b/src/tools/clippy/clippy_lints/src/derivable_impls.rs
@@ -1,5 +1,5 @@
 use clippy_utils::diagnostics::span_lint_and_help;
-use clippy_utils::{is_automatically_derived, is_default_equivalent, peel_blocks};
+use clippy_utils::{is_default_equivalent, peel_blocks};
 use rustc_hir::{
     def::{DefKind, Res},
     Body, Expr, ExprKind, GenericArg, Impl, ImplItemKind, Item, ItemKind, Node, PathSegment, QPath, TyKind,
@@ -71,8 +71,7 @@ impl<'tcx> LateLintPass<'tcx> for DerivableImpls {
                 self_ty,
                 ..
             }) = item.kind;
-            if let attrs = cx.tcx.hir().attrs(item.hir_id());
-            if !is_automatically_derived(attrs);
+            if !cx.tcx.has_attr(item.def_id.to_def_id(), sym::automatically_derived);
             if !item.span.from_expansion();
             if let Some(def_id) = trait_ref.trait_def_id();
             if cx.tcx.is_diagnostic_item(sym::Default, def_id);
@@ -81,6 +80,7 @@ impl<'tcx> LateLintPass<'tcx> for DerivableImpls {
             if let ImplItemKind::Fn(_, b) = &impl_item.kind;
             if let Body { value: func_expr, .. } = cx.tcx.hir().body(*b);
             if let Some(adt_def) = cx.tcx.type_of(item.def_id).ty_adt_def();
+            if let attrs = cx.tcx.hir().attrs(item.hir_id());
             if !attrs.iter().any(|attr| attr.doc_str().is_some());
             if let child_attrs = cx.tcx.hir().attrs(impl_item_hir);
             if !child_attrs.iter().any(|attr| attr.doc_str().is_some());
diff --git a/src/tools/clippy/clippy_lints/src/derive.rs b/src/tools/clippy/clippy_lints/src/derive.rs
index 557e101494e..545bc7d2103 100644
--- a/src/tools/clippy/clippy_lints/src/derive.rs
+++ b/src/tools/clippy/clippy_lints/src/derive.rs
@@ -1,7 +1,7 @@
 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note, span_lint_and_then};
 use clippy_utils::paths;
 use clippy_utils::ty::{implements_trait, is_copy};
-use clippy_utils::{is_automatically_derived, is_lint_allowed, match_def_path};
+use clippy_utils::{is_lint_allowed, match_def_path};
 use if_chain::if_chain;
 use rustc_hir::intravisit::{walk_expr, walk_fn, walk_item, FnKind, Visitor};
 use rustc_hir::{
@@ -171,8 +171,8 @@ impl<'tcx> LateLintPass<'tcx> for Derive {
         }) = item.kind
         {
             let ty = cx.tcx.type_of(item.def_id);
-            let attrs = cx.tcx.hir().attrs(item.hir_id());
-            let is_automatically_derived = is_automatically_derived(attrs);
+            let is_automatically_derived =
+                cx.tcx.has_attr(item.def_id.to_def_id(), sym::automatically_derived);
 
             check_hash_peq(cx, item.span, trait_ref, ty, is_automatically_derived);
             check_ord_partial_ord(cx, item.span, trait_ref, ty, is_automatically_derived);
@@ -201,7 +201,7 @@ fn check_hash_peq<'tcx>(
         then {
             // Look for the PartialEq implementations for `ty`
             cx.tcx.for_each_relevant_impl(peq_trait_def_id, ty, |impl_id| {
-                let peq_is_automatically_derived = is_automatically_derived(cx.tcx.get_attrs(impl_id));
+                let peq_is_automatically_derived = cx.tcx.has_attr(impl_id, sym::automatically_derived);
 
                 if peq_is_automatically_derived == hash_is_automatically_derived {
                     return;
@@ -255,7 +255,7 @@ fn check_ord_partial_ord<'tcx>(
         then {
             // Look for the PartialOrd implementations for `ty`
             cx.tcx.for_each_relevant_impl(partial_ord_trait_def_id, ty, |impl_id| {
-                let partial_ord_is_automatically_derived = is_automatically_derived(cx.tcx.get_attrs(impl_id));
+                let partial_ord_is_automatically_derived = cx.tcx.has_attr(impl_id, sym::automatically_derived);
 
                 if partial_ord_is_automatically_derived == ord_is_automatically_derived {
                     return;
diff --git a/src/tools/clippy/clippy_lints/src/functions/must_use.rs b/src/tools/clippy/clippy_lints/src/functions/must_use.rs
index 38e943d2eb8..6672a6cb0b5 100644
--- a/src/tools/clippy/clippy_lints/src/functions/must_use.rs
+++ b/src/tools/clippy/clippy_lints/src/functions/must_use.rs
@@ -13,13 +13,13 @@ use clippy_utils::attrs::is_proc_macro;
 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_then};
 use clippy_utils::source::snippet_opt;
 use clippy_utils::ty::is_must_use_ty;
-use clippy_utils::{match_def_path, must_use_attr, return_ty, trait_ref_of_method};
+use clippy_utils::{match_def_path, return_ty, trait_ref_of_method};
 
 use super::{DOUBLE_MUST_USE, MUST_USE_CANDIDATE, MUST_USE_UNIT};
 
 pub(super) fn check_item<'tcx>(cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
     let attrs = cx.tcx.hir().attrs(item.hir_id());
-    let attr = must_use_attr(attrs);
+    let attr = cx.tcx.get_attr(item.def_id.to_def_id(), sym::must_use);
     if let hir::ItemKind::Fn(ref sig, _generics, ref body_id) = item.kind {
         let is_public = cx.access_levels.is_exported(item.def_id);
         let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
@@ -44,7 +44,7 @@ pub(super) fn check_impl_item<'tcx>(cx: &LateContext<'tcx>, item: &'tcx hir::Imp
         let is_public = cx.access_levels.is_exported(item.def_id);
         let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
         let attrs = cx.tcx.hir().attrs(item.hir_id());
-        let attr = must_use_attr(attrs);
+        let attr = cx.tcx.get_attr(item.def_id.to_def_id(), sym::must_use);
         if let Some(attr) = attr {
             check_needless_must_use(cx, sig.decl, item.hir_id(), item.span, fn_header_span, attr);
         } else if is_public && !is_proc_macro(cx.sess(), attrs) && trait_ref_of_method(cx, item.def_id).is_none() {
@@ -67,7 +67,7 @@ pub(super) fn check_trait_item<'tcx>(cx: &LateContext<'tcx>, item: &'tcx hir::Tr
         let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
 
         let attrs = cx.tcx.hir().attrs(item.hir_id());
-        let attr = must_use_attr(attrs);
+        let attr = cx.tcx.get_attr(item.def_id.to_def_id(), sym::must_use);
         if let Some(attr) = attr {
             check_needless_must_use(cx, sig.decl, item.hir_id(), item.span, fn_header_span, attr);
         } else if let hir::TraitFn::Provided(eid) = *eid {
diff --git a/src/tools/clippy/clippy_lints/src/manual_non_exhaustive.rs b/src/tools/clippy/clippy_lints/src/manual_non_exhaustive.rs
index b8d620d8171..09164690700 100644
--- a/src/tools/clippy/clippy_lints/src/manual_non_exhaustive.rs
+++ b/src/tools/clippy/clippy_lints/src/manual_non_exhaustive.rs
@@ -1,4 +1,3 @@
-use clippy_utils::attrs::is_doc_hidden;
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::source::snippet_opt;
 use clippy_utils::{is_lint_allowed, meets_msrv, msrvs};
@@ -161,7 +160,7 @@ impl<'tcx> LateLintPass<'tcx> for ManualNonExhaustiveEnum {
                 let id = cx.tcx.hir().local_def_id(v.id);
                 (matches!(v.data, hir::VariantData::Unit(_))
                     && v.ident.as_str().starts_with('_')
-                    && is_doc_hidden(cx.tcx.get_attrs(id.to_def_id())))
+                    && cx.tcx.is_doc_hidden(id.to_def_id()))
                 .then(|| (id, v.span))
             });
             if let Some((id, span)) = iter.next()
diff --git a/src/tools/clippy/clippy_lints/src/matches/match_wild_enum.rs b/src/tools/clippy/clippy_lints/src/matches/match_wild_enum.rs
index 93bf0dc62e0..fc45ccee185 100644
--- a/src/tools/clippy/clippy_lints/src/matches/match_wild_enum.rs
+++ b/src/tools/clippy/clippy_lints/src/matches/match_wild_enum.rs
@@ -193,6 +193,5 @@ impl<'a> CommonPrefixSearcher<'a> {
 }
 
 fn is_hidden(cx: &LateContext<'_>, variant_def: &VariantDef) -> bool {
-    let attrs = cx.tcx.get_attrs(variant_def.def_id);
-    clippy_utils::attrs::is_doc_hidden(attrs) || clippy_utils::attrs::is_unstable(attrs)
+    cx.tcx.is_doc_hidden(variant_def.def_id) || cx.tcx.has_attr(variant_def.def_id, sym::unstable)
 }
diff --git a/src/tools/clippy/clippy_lints/src/new_without_default.rs b/src/tools/clippy/clippy_lints/src/new_without_default.rs
index 2f733f221d5..2bdccb42507 100644
--- a/src/tools/clippy/clippy_lints/src/new_without_default.rs
+++ b/src/tools/clippy/clippy_lints/src/new_without_default.rs
@@ -85,7 +85,7 @@ impl<'tcx> LateLintPass<'tcx> for NewWithoutDefault {
                             // can't be implemented for unsafe new
                             return;
                         }
-                        if clippy_utils::is_doc_hidden(cx.tcx.hir().attrs(id)) {
+                        if cx.tcx.is_doc_hidden(impl_item.def_id) {
                             // shouldn't be implemented when it is hidden in docs
                             return;
                         }
diff --git a/src/tools/clippy/clippy_lints/src/partialeq_ne_impl.rs b/src/tools/clippy/clippy_lints/src/partialeq_ne_impl.rs
index 1469cb434c0..09ac514d014 100644
--- a/src/tools/clippy/clippy_lints/src/partialeq_ne_impl.rs
+++ b/src/tools/clippy/clippy_lints/src/partialeq_ne_impl.rs
@@ -1,5 +1,4 @@
 use clippy_utils::diagnostics::span_lint_hir;
-use clippy_utils::is_automatically_derived;
 use if_chain::if_chain;
 use rustc_hir::{Impl, Item, ItemKind};
 use rustc_lint::{LateContext, LateLintPass};
@@ -37,8 +36,7 @@ impl<'tcx> LateLintPass<'tcx> for PartialEqNeImpl {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
         if_chain! {
             if let ItemKind::Impl(Impl { of_trait: Some(ref trait_ref), items: impl_items, .. }) = item.kind;
-            let attrs = cx.tcx.hir().attrs(item.hir_id());
-            if !is_automatically_derived(attrs);
+            if !cx.tcx.has_attr(item.def_id.to_def_id(), sym::automatically_derived);
             if let Some(eq_trait) = cx.tcx.lang_items().eq_trait();
             if trait_ref.path.res.def_id() == eq_trait;
             then {
diff --git a/src/tools/clippy/clippy_lints/src/significant_drop_in_scrutinee.rs b/src/tools/clippy/clippy_lints/src/significant_drop_in_scrutinee.rs
index 94ae0c8f5a6..f300acf0fb2 100644
--- a/src/tools/clippy/clippy_lints/src/significant_drop_in_scrutinee.rs
+++ b/src/tools/clippy/clippy_lints/src/significant_drop_in_scrutinee.rs
@@ -290,7 +290,7 @@ impl<'a, 'tcx> SigDropHelper<'a, 'tcx> {
 
     fn has_sig_drop_attr(&mut self, cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
         if let Some(adt) = ty.ty_adt_def() {
-            if get_attr(cx.sess(), cx.tcx.get_attrs(adt.did()), "has_significant_drop").count() > 0 {
+            if get_attr(cx.sess(), cx.tcx.get_attrs_unchecked(adt.did()), "has_significant_drop").count() > 0 {
                 return true;
             }
         }
diff --git a/src/tools/clippy/clippy_utils/src/attrs.rs b/src/tools/clippy/clippy_utils/src/attrs.rs
index 7f448175e32..904b1a05ccc 100644
--- a/src/tools/clippy/clippy_utils/src/attrs.rs
+++ b/src/tools/clippy/clippy_utils/src/attrs.rs
@@ -1,6 +1,7 @@
-use rustc_ast::{ast, attr};
+use rustc_ast::ast;
 use rustc_errors::Applicability;
 use rustc_session::Session;
+use rustc_ast::attr;
 use rustc_span::sym;
 use std::str::FromStr;
 
@@ -158,7 +159,3 @@ pub fn is_doc_hidden(attrs: &[ast::Attribute]) -> bool {
         .any(|l| attr::list_contains_name(&l, sym::hidden))
 }
 
-/// Return true if the attributes contain `#[unstable]`
-pub fn is_unstable(attrs: &[ast::Attribute]) -> bool {
-    attrs.iter().any(|attr| attr.has_name(sym::unstable))
-}
diff --git a/src/tools/clippy/clippy_utils/src/lib.rs b/src/tools/clippy/clippy_utils/src/lib.rs
index 7d46952d971..98a073d122e 100644
--- a/src/tools/clippy/clippy_utils/src/lib.rs
+++ b/src/tools/clippy/clippy_utils/src/lib.rs
@@ -66,7 +66,7 @@ use std::lazy::SyncOnceCell;
 use std::sync::{Mutex, MutexGuard};
 
 use if_chain::if_chain;
-use rustc_ast::ast::{self, Attribute, LitKind};
+use rustc_ast::ast::{self, LitKind};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::unhash::UnhashMap;
 use rustc_hir as hir;
@@ -1472,12 +1472,6 @@ pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>
     }
 }
 
-/// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
-/// implementations have.
-pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
-    has_attr(attrs, sym::automatically_derived)
-}
-
 pub fn is_self(slf: &Param<'_>) -> bool {
     if let PatKind::Binding(.., name, _) = slf.pat.kind {
         name.name == kw::SelfLower
@@ -1724,11 +1718,6 @@ pub fn get_async_fn_body<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'t
     None
 }
 
-// Finds the `#[must_use]` attribute, if any
-pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
-    attrs.iter().find(|a| a.has_name(sym::must_use))
-}
-
 // check if expr is calling method or function with #[must_use] attribute
 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
     let did = match expr.kind {
@@ -1745,7 +1734,7 @@ pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
         _ => None,
     };
 
-    did.map_or(false, |did| must_use_attr(cx.tcx.get_attrs(did)).is_some())
+    did.map_or(false, |did| cx.tcx.has_attr(did, sym::must_use))
 }
 
 /// Checks if an expression represents the identity function
diff --git a/src/tools/clippy/clippy_utils/src/ty.rs b/src/tools/clippy/clippy_utils/src/ty.rs
index 901e3e5390c..7f14a306d0e 100644
--- a/src/tools/clippy/clippy_utils/src/ty.rs
+++ b/src/tools/clippy/clippy_utils/src/ty.rs
@@ -22,7 +22,7 @@ use rustc_trait_selection::infer::InferCtxtExt;
 use rustc_trait_selection::traits::query::normalize::AtExt;
 use std::iter;
 
-use crate::{match_def_path, must_use_attr, path_res, paths};
+use crate::{match_def_path, path_res, paths};
 
 // Checks if the given type implements copy.
 pub fn is_copy<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
@@ -178,18 +178,18 @@ pub fn has_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
 // Returns whether the type has #[must_use] attribute
 pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
     match ty.kind() {
-        ty::Adt(adt, _) => must_use_attr(cx.tcx.get_attrs(adt.did())).is_some(),
-        ty::Foreign(ref did) => must_use_attr(cx.tcx.get_attrs(*did)).is_some(),
+        ty::Adt(adt, _) => cx.tcx.has_attr(adt.did(), sym::must_use),
+        ty::Foreign(did) => cx.tcx.has_attr(*did, sym::must_use),
         ty::Slice(ty) | ty::Array(ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _) => {
             // for the Array case we don't need to care for the len == 0 case
             // because we don't want to lint functions returning empty arrays
             is_must_use_ty(cx, *ty)
         },
         ty::Tuple(substs) => substs.iter().any(|ty| is_must_use_ty(cx, ty)),
-        ty::Opaque(ref def_id, _) => {
+        ty::Opaque(def_id, _) => {
             for (predicate, _) in cx.tcx.explicit_item_bounds(*def_id) {
                 if let ty::PredicateKind::Trait(trait_predicate) = predicate.kind().skip_binder() {
-                    if must_use_attr(cx.tcx.get_attrs(trait_predicate.trait_ref.def_id)).is_some() {
+                    if cx.tcx.has_attr(trait_predicate.trait_ref.def_id, sym::must_use) {
                         return true;
                     }
                 }
@@ -199,7 +199,7 @@ pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
         ty::Dynamic(binder, _) => {
             for predicate in binder.iter() {
                 if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() {
-                    if must_use_attr(cx.tcx.get_attrs(trait_ref.def_id)).is_some() {
+                    if cx.tcx.has_attr(trait_ref.def_id, sym::must_use) {
                         return true;
                     }
                 }