Use interned strings when possible, for efficiency purposes (#14963)

Also, a number of unnecessary `.as_str()` calls have been removed for
clarity.

changelog: none

Author: llogiq

clippy_lints/src/attrs/deprecated_cfg_attr.rs

@@ -61,7 +61,7 @@ pub(super) fn check_clippy(cx: &EarlyContext<'_>, attr: &Attribute) {
 
 fn check_deprecated_cfg_recursively(cx: &EarlyContext<'_>, attr: &rustc_ast::MetaItem) {
     if let Some(ident) = attr.ident() {
-        if ["any", "all", "not"].contains(&ident.name.as_str()) {
+        if matches!(ident.name, sym::any | sym::all | sym::not) {
             let Some(list) = attr.meta_item_list() else { return };
             for item in list.iter().filter_map(|item| item.meta_item()) {
                 check_deprecated_cfg_recursively(cx, item);

clippy_lints/src/casts/cast_ptr_alignment.rs

@@ -61,7 +61,7 @@ fn is_used_as_unaligned(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
     };
     match parent.kind {
         ExprKind::MethodCall(name, self_arg, ..) if self_arg.hir_id == e.hir_id => {
-            if matches!(name.ident.as_str(), "read_unaligned" | "write_unaligned")
+            if matches!(name.ident.name, sym::read_unaligned | sym::write_unaligned)
                 && let Some(def_id) = cx.typeck_results().type_dependent_def_id(parent.hir_id)
                 && let Some(def_id) = cx.tcx.impl_of_method(def_id)
                 && cx.tcx.type_of(def_id).instantiate_identity().is_raw_ptr()

clippy_lints/src/if_let_mutex.rs

@@ -1,14 +1,13 @@
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::ty::is_type_diagnostic_item;
 use clippy_utils::visitors::for_each_expr_without_closures;
-use clippy_utils::{eq_expr_value, higher};
+use clippy_utils::{eq_expr_value, higher, sym};
 use core::ops::ControlFlow;
 use rustc_errors::Diag;
 use rustc_hir::{Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
 use rustc_span::edition::Edition::Edition2024;
-use rustc_span::sym;
 
 declare_clippy_lint! {
     /// ### What it does
@@ -94,7 +93,7 @@ fn mutex_lock_call<'tcx>(
     op_mutex: Option<&'tcx Expr<'_>>,
 ) -> ControlFlow<&'tcx Expr<'tcx>> {
     if let ExprKind::MethodCall(path, self_arg, [], _) = &expr.kind
-        && path.ident.as_str() == "lock"
+        && path.ident.name == sym::lock
         && let ty = cx.typeck_results().expr_ty(self_arg).peel_refs()
         && is_type_diagnostic_item(cx, ty, sym::Mutex)
         && op_mutex.is_none_or(|op| eq_expr_value(cx, self_arg, op))

clippy_lints/src/implicit_saturating_sub.rs

@@ -3,15 +3,15 @@ use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
 use clippy_utils::msrvs::{self, Msrv};
 use clippy_utils::sugg::{Sugg, make_binop};
 use clippy_utils::{
-    SpanlessEq, eq_expr_value, higher, is_in_const_context, is_integer_literal, peel_blocks, peel_blocks_with_stmt,
+    SpanlessEq, eq_expr_value, higher, is_in_const_context, is_integer_literal, peel_blocks, peel_blocks_with_stmt, sym,
 };
 use rustc_ast::ast::LitKind;
 use rustc_data_structures::packed::Pu128;
 use rustc_errors::Applicability;
 use rustc_hir::{AssignOpKind, BinOp, BinOpKind, Expr, ExprKind, QPath};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::impl_lint_pass;
-use rustc_span::Span;
+use rustc_span::{Span, Symbol};
 
 declare_clippy_lint! {
     /// ### What it does
@@ -325,7 +325,7 @@ fn check_with_condition<'tcx>(
         }
 
         // Get the variable name
-        let var_name = ares_path.segments[0].ident.name.as_str();
+        let var_name = ares_path.segments[0].ident.name;
         match cond_num_val.kind {
             ExprKind::Lit(cond_lit) => {
                 // Check if the constant is zero
@@ -337,7 +337,7 @@ fn check_with_condition<'tcx>(
                 }
             },
             ExprKind::Path(QPath::TypeRelative(_, name)) => {
-                if name.ident.as_str() == "MIN"
+                if name.ident.name == sym::MIN
                     && let Some(const_id) = cx.typeck_results().type_dependent_def_id(cond_num_val.hir_id)
                     && let Some(impl_id) = cx.tcx.impl_of_method(const_id)
                     && let None = cx.tcx.impl_trait_ref(impl_id) // An inherent impl
@@ -348,7 +348,7 @@ fn check_with_condition<'tcx>(
             },
             ExprKind::Call(func, []) => {
                 if let ExprKind::Path(QPath::TypeRelative(_, name)) = func.kind
-                    && name.ident.as_str() == "min_value"
+                    && name.ident.name == sym::min_value
                     && let Some(func_id) = cx.typeck_results().type_dependent_def_id(func.hir_id)
                     && let Some(impl_id) = cx.tcx.impl_of_method(func_id)
                     && let None = cx.tcx.impl_trait_ref(impl_id) // An inherent impl
@@ -383,7 +383,7 @@ fn subtracts_one<'a>(cx: &LateContext<'_>, expr: &'a Expr<'a>) -> Option<&'a Exp
     }
 }
 
-fn print_lint_and_sugg(cx: &LateContext<'_>, var_name: &str, expr: &Expr<'_>) {
+fn print_lint_and_sugg(cx: &LateContext<'_>, var_name: Symbol, expr: &Expr<'_>) {
     span_lint_and_sugg(
         cx,
         IMPLICIT_SATURATING_SUB,

clippy_lints/src/manual_clamp.rs

@@ -8,7 +8,7 @@ use clippy_utils::ty::implements_trait;
 use clippy_utils::visitors::is_const_evaluatable;
 use clippy_utils::{
     MaybePath, eq_expr_value, is_diag_trait_item, is_in_const_context, is_trait_method, path_res, path_to_local_id,
-    peel_blocks, peel_blocks_with_stmt,
+    peel_blocks, peel_blocks_with_stmt, sym,
 };
 use itertools::Itertools;
 use rustc_errors::{Applicability, Diag};
@@ -18,7 +18,6 @@ use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::Ty;
 use rustc_session::impl_lint_pass;
 use rustc_span::Span;
-use rustc_span::symbol::sym;
 use std::cmp::Ordering;
 use std::ops::Deref;
 
@@ -299,9 +298,9 @@ fn is_max_min_pattern<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> O
         && (cx.typeck_results().expr_ty_adjusted(input).is_floating_point() || is_trait_method(cx, receiver, sym::Ord))
     {
         let is_float = cx.typeck_results().expr_ty_adjusted(input).is_floating_point();
-        let (min, max) = match (seg_first.ident.as_str(), seg_second.ident.as_str()) {
-            ("min", "max") => (arg_second, arg_first),
-            ("max", "min") => (arg_first, arg_second),
+        let (min, max) = match (seg_first.ident.name, seg_second.ident.name) {
+            (sym::min, sym::max) => (arg_second, arg_first),
+            (sym::max, sym::min) => (arg_first, arg_second),
             _ => return None,
         };
         Some(ClampSuggestion {

clippy_lints/src/manual_string_new.rs

@@ -1,11 +1,12 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::sym;
 use rustc_ast::LitKind;
 use rustc_errors::Applicability::MachineApplicable;
 use rustc_hir::{Expr, ExprKind, PathSegment, QPath, TyKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
 use rustc_session::declare_lint_pass;
-use rustc_span::{Span, sym};
+use rustc_span::Span;
 
 declare_clippy_lint! {
     /// ### What it does
@@ -89,9 +90,10 @@ fn warn_then_suggest(cx: &LateContext<'_>, span: Span) {
 
 /// Tries to parse an expression as a method call, emitting the warning if necessary.
 fn parse_method_call(cx: &LateContext<'_>, span: Span, path_segment: &PathSegment<'_>, receiver: &Expr<'_>) {
-    let ident = path_segment.ident.as_str();
     let method_arg_kind = &receiver.kind;
-    if ["to_string", "to_owned", "into"].contains(&ident) && is_expr_kind_empty_str(method_arg_kind) {
+    if matches!(path_segment.ident.name, sym::to_string | sym::to_owned | sym::into)
+        && is_expr_kind_empty_str(method_arg_kind)
+    {
         warn_then_suggest(cx, span);
     } else if let ExprKind::Call(func, [arg]) = method_arg_kind {
         // If our first argument is a function call itself, it could be an `unwrap`-like function.

clippy_lints/src/match_result_ok.rs

@@ -1,12 +1,11 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet_with_context;
 use clippy_utils::ty::is_type_diagnostic_item;
-use clippy_utils::{higher, is_res_lang_ctor};
+use clippy_utils::{higher, is_res_lang_ctor, sym};
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind, LangItem, PatKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
-use rustc_span::sym;
 
 declare_clippy_lint! {
     /// ### What it does
@@ -57,7 +56,7 @@ impl<'tcx> LateLintPass<'tcx> for MatchResultOk {
 
         if let ExprKind::MethodCall(ok_path, recv, [], ..) = let_expr.kind //check is expr.ok() has type Result<T,E>.ok(, _)
             && let PatKind::TupleStruct(ref pat_path, [ok_pat], _)  = let_pat.kind //get operation
-            && ok_path.ident.as_str() == "ok"
+            && ok_path.ident.name == sym::ok
             && is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(recv), sym::Result)
             && is_res_lang_ctor(cx, cx.qpath_res(pat_path, let_pat.hir_id), LangItem::OptionSome)
             && let ctxt = expr.span.ctxt()

clippy_lints/src/matches/match_str_case_mismatch.rs

@@ -1,6 +1,7 @@
 use std::ops::ControlFlow;
 
 use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::sym;
 use clippy_utils::ty::is_type_lang_item;
 use rustc_ast::ast::LitKind;
 use rustc_errors::Applicability;
@@ -42,7 +43,7 @@ impl<'tcx> Visitor<'tcx> for MatchExprVisitor<'_, 'tcx> {
     type Result = ControlFlow<CaseMethod>;
     fn visit_expr(&mut self, ex: &'tcx Expr<'_>) -> Self::Result {
         if let ExprKind::MethodCall(segment, receiver, [], _) = ex.kind {
-            let result = self.case_altered(segment.ident.as_str(), receiver);
+            let result = self.case_altered(segment.ident.name, receiver);
             if result.is_break() {
                 return result;
             }
@@ -53,7 +54,7 @@ impl<'tcx> Visitor<'tcx> for MatchExprVisitor<'_, 'tcx> {
 }
 
 impl MatchExprVisitor<'_, '_> {
-    fn case_altered(&mut self, segment_ident: &str, receiver: &Expr<'_>) -> ControlFlow<CaseMethod> {
+    fn case_altered(&mut self, segment_ident: Symbol, receiver: &Expr<'_>) -> ControlFlow<CaseMethod> {
         if let Some(case_method) = get_case_method(segment_ident) {
             let ty = self.cx.typeck_results().expr_ty(receiver).peel_refs();
 
@@ -66,12 +67,12 @@ impl MatchExprVisitor<'_, '_> {
     }
 }
 
-fn get_case_method(segment_ident_str: &str) -> Option<CaseMethod> {
-    match segment_ident_str {
-        "to_lowercase" => Some(CaseMethod::LowerCase),
-        "to_ascii_lowercase" => Some(CaseMethod::AsciiLowerCase),
-        "to_uppercase" => Some(CaseMethod::UpperCase),
-        "to_ascii_uppercase" => Some(CaseMethod::AsciiUppercase),
+fn get_case_method(segment_ident: Symbol) -> Option<CaseMethod> {
+    match segment_ident {
+        sym::to_lowercase => Some(CaseMethod::LowerCase),
+        sym::to_ascii_lowercase => Some(CaseMethod::AsciiLowerCase),
+        sym::to_uppercase => Some(CaseMethod::UpperCase),
+        sym::to_ascii_uppercase => Some(CaseMethod::AsciiUppercase),
         _ => None,
     }
 }

clippy_lints/src/methods/iter_kv_map.rs

@@ -46,7 +46,7 @@ pub(super) fn check<'tcx>(
 
         if let ExprKind::Path(rustc_hir::QPath::Resolved(_, path)) = body_expr.kind
             && let [local_ident] = path.segments
-            && local_ident.ident.as_str() == bound_ident.as_str()
+            && local_ident.ident.name == bound_ident.name
         {
             span_lint_and_sugg(
                 cx,

clippy_lints/src/methods/manual_saturating_arithmetic.rs

@@ -72,9 +72,9 @@ fn is_min_or_max(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<MinMax> {
     if let hir::ExprKind::Call(func, []) = &expr.kind
         && let hir::ExprKind::Path(hir::QPath::TypeRelative(_, segment)) = &func.kind
     {
-        match segment.ident.as_str() {
-            "max_value" => return Some(MinMax::Max),
-            "min_value" => return Some(MinMax::Min),
+        match segment.ident.name {
+            sym::max_value => return Some(MinMax::Max),
+            sym::min_value => return Some(MinMax::Min),
             _ => {},
         }
     }