Auto merge of #91957 - nnethercote:rm-SymbolStr, r=oli-obk

Remove `SymbolStr`

This was originally proposed in rust-lang/rust#74554 (comment). As well as removing the icky `SymbolStr` type, it allows the removal of a lot of `&` and `*` occurrences.

Best reviewed one commit at a time.

r? `@oli-obk`

Author: bors

clippy_lints/src/attrs.rs

@@ -17,7 +17,7 @@ use rustc_semver::RustcVersion;
 use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::Span;
 use rustc_span::sym;
-use rustc_span::symbol::{Symbol, SymbolStr};
+use rustc_span::symbol::Symbol;
 use semver::Version;
 
 static UNIX_SYSTEMS: &[&str] = &[
@@ -310,8 +310,8 @@ impl<'tcx> LateLintPass<'tcx> for Attributes {
                                             || is_word(lint, sym::deprecated)
                                             || is_word(lint, sym!(unreachable_pub))
                                             || is_word(lint, sym!(unused))
-                                            || extract_clippy_lint(lint).map_or(false, |s| s == "wildcard_imports")
-                                            || extract_clippy_lint(lint).map_or(false, |s| s == "enum_glob_use")
+                                            || extract_clippy_lint(lint).map_or(false, |s| s.as_str() == "wildcard_imports")
+                                            || extract_clippy_lint(lint).map_or(false, |s| s.as_str() == "enum_glob_use")
                                         {
                                             return;
                                         }
@@ -370,15 +370,15 @@ impl<'tcx> LateLintPass<'tcx> for Attributes {
 }
 
 /// Returns the lint name if it is clippy lint.
-fn extract_clippy_lint(lint: &NestedMetaItem) -> Option<SymbolStr> {
+fn extract_clippy_lint(lint: &NestedMetaItem) -> Option<Symbol> {
     if_chain! {
         if let Some(meta_item) = lint.meta_item();
         if meta_item.path.segments.len() > 1;
         if let tool_name = meta_item.path.segments[0].ident;
         if tool_name.name == sym::clippy;
         then {
             let lint_name = meta_item.path.segments.last().unwrap().ident.name;
-            return Some(lint_name.as_str());
+            return Some(lint_name);
         }
     }
     None
@@ -387,7 +387,7 @@ fn extract_clippy_lint(lint: &NestedMetaItem) -> Option<SymbolStr> {
 fn check_clippy_lint_names(cx: &LateContext<'_>, name: Symbol, items: &[NestedMetaItem]) {
     for lint in items {
         if let Some(lint_name) = extract_clippy_lint(lint) {
-            if lint_name == "restriction" && name != sym::allow {
+            if lint_name.as_str() == "restriction" && name != sym::allow {
                 span_lint_and_help(
                     cx,
                     BLANKET_CLIPPY_RESTRICTION_LINTS,
@@ -486,7 +486,7 @@ fn check_attrs(cx: &LateContext<'_>, span: Span, name: Symbol, attrs: &[Attribut
 
 fn check_semver(cx: &LateContext<'_>, span: Span, lit: &Lit) {
     if let LitKind::Str(is, _) = lit.kind {
-        if Version::parse(&is.as_str()).is_ok() {
+        if Version::parse(is.as_str()).is_ok() {
             return;
         }
     }
@@ -619,7 +619,7 @@ fn check_mismatched_target_os(cx: &EarlyContext<'_>, attr: &Attribute) {
                     MetaItemKind::Word => {
                         if_chain! {
                             if let Some(ident) = meta.ident();
-                            if let Some(os) = find_os(&*ident.name.as_str());
+                            if let Some(os) = find_os(ident.name.as_str());
                             then {
                                 mismatched.push((os, ident.span));
                             }

clippy_lints/src/booleans.rs

@@ -272,7 +272,7 @@ fn simplify_not(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
                 .copied()
                 .flat_map(|(a, b)| vec![(a, b), (b, a)])
                 .find(|&(a, _)| {
-                    let path: &str = &path.ident.name.as_str();
+                    let path: &str = path.ident.name.as_str();
                     a == path
                 })
                 .and_then(|(_, neg_method)| Some(format!("{}.{}()", snippet_opt(cx, args[0].span)?, neg_method)))

clippy_lints/src/checked_conversions.rs

@@ -321,8 +321,8 @@ fn get_implementing_type<'a>(path: &QPath<'_>, candidates: &'a [&str], function:
         if let TyKind::Path(QPath::Resolved(None, tp)) = &ty.kind;
         if let [int] = &*tp.segments;
         then {
-            let name = &int.ident.name.as_str();
-            candidates.iter().find(|c| name == *c).copied()
+            let name = int.ident.name.as_str();
+            candidates.iter().find(|c| &name == *c).copied()
         } else {
             None
         }
@@ -335,8 +335,8 @@ fn int_ty_to_sym<'tcx>(path: &QPath<'_>) -> Option<&'tcx str> {
         if let QPath::Resolved(_, path) = *path;
         if let [ty] = &*path.segments;
         then {
-            let name = &ty.ident.name.as_str();
-            INTS.iter().find(|c| name == *c).copied()
+            let name = ty.ident.name.as_str();
+            INTS.iter().find(|c| &name == *c).copied()
         } else {
             None
         }

clippy_lints/src/doc.rs

@@ -437,7 +437,7 @@ fn check_attrs<'a>(cx: &LateContext<'_>, valid_idents: &FxHashSet<String>, attrs
 
     for attr in attrs {
         if let AttrKind::DocComment(comment_kind, comment) = attr.kind {
-            let (comment, current_spans) = strip_doc_comment_decoration(&comment.as_str(), comment_kind, attr.span);
+            let (comment, current_spans) = strip_doc_comment_decoration(comment.as_str(), comment_kind, attr.span);
             spans.extend_from_slice(&current_spans);
             doc.push_str(&comment);
         } else if attr.has_name(sym::doc) {

clippy_lints/src/duration_subsec.rs

@@ -49,7 +49,7 @@ impl<'tcx> LateLintPass<'tcx> for DurationSubsec {
             if match_type(cx, cx.typeck_results().expr_ty(&args[0]).peel_refs(), &paths::DURATION);
             if let Some((Constant::Int(divisor), _)) = constant(cx, cx.typeck_results(), right);
             then {
-                let suggested_fn = match (method_path.ident.as_str().as_ref(), divisor) {
+                let suggested_fn = match (method_path.ident.as_str(), divisor) {
                     ("subsec_micros", 1_000) | ("subsec_nanos", 1_000_000) => "subsec_millis",
                     ("subsec_nanos", 1_000) => "subsec_micros",
                     _ => return,

clippy_lints/src/enum_variants.rs

@@ -153,7 +153,7 @@ fn check_variant(
             );
         }
     }
-    let first = &def.variants[0].ident.name.as_str();
+    let first = def.variants[0].ident.name.as_str();
     let mut pre = &first[..str_utils::camel_case_until(&*first).byte_index];
     let mut post = &first[str_utils::camel_case_start(&*first).byte_index..];
     for var in def.variants {

clippy_lints/src/float_literal.rs

@@ -68,7 +68,7 @@ impl<'tcx> LateLintPass<'tcx> for FloatLiteral {
             if let LitKind::Float(sym, lit_float_ty) = lit.node;
             then {
                 let sym_str = sym.as_str();
-                let formatter = FloatFormat::new(&sym_str);
+                let formatter = FloatFormat::new(sym_str);
                 // Try to bail out if the float is for sure fine.
                 // If its within the 2 decimal digits of being out of precision we
                 // check if the parsed representation is the same as the string

clippy_lints/src/floating_point_arithmetic.rs

@@ -595,7 +595,7 @@ fn are_same_base_logs(cx: &LateContext<'_>, expr_a: &Expr<'_>, expr_b: &Expr<'_>
             return method_name_a.as_str() == method_name_b.as_str() &&
                 args_a.len() == args_b.len() &&
                 (
-                    ["ln", "log2", "log10"].contains(&&*method_name_a.as_str()) ||
+                    ["ln", "log2", "log10"].contains(&method_name_a.as_str()) ||
                     method_name_a.as_str() == "log" && args_a.len() == 2 && eq_expr_value(cx, &args_a[1], &args_b[1])
                 );
         }
@@ -692,7 +692,7 @@ impl<'tcx> LateLintPass<'tcx> for FloatingPointArithmetic {
             let recv_ty = cx.typeck_results().expr_ty(&args[0]);
 
             if recv_ty.is_floating_point() {
-                match &*path.ident.name.as_str() {
+                match path.ident.name.as_str() {
                     "ln" => check_ln1p(cx, expr, args),
                     "log" => check_log_base(cx, expr, args),
                     "powf" => check_powf(cx, expr, args),

clippy_lints/src/iter_not_returning_iterator.rs

@@ -42,7 +42,7 @@ declare_lint_pass!(IterNotReturningIterator => [ITER_NOT_RETURNING_ITERATOR]);
 
 impl LateLintPass<'_> for IterNotReturningIterator {
     fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &'tcx ImplItem<'tcx>) {
-        let name: &str = &impl_item.ident.name.as_str();
+        let name = impl_item.ident.name.as_str();
         if_chain! {
             if let ImplItemKind::Fn(fn_sig, _) = &impl_item.kind;
             let ret_ty = return_ty(cx, impl_item.hir_id());

clippy_lints/src/loops/mod.rs

@@ -659,7 +659,7 @@ fn check_for_loop_arg(cx: &LateContext<'_>, pat: &Pat<'_>, arg: &Expr<'_>) {
     let mut next_loop_linted = false; // whether or not ITER_NEXT_LOOP lint was used
 
     if let ExprKind::MethodCall(method, _, [self_arg], _) = arg.kind {
-        let method_name = &*method.ident.as_str();
+        let method_name = method.ident.as_str();
         // check for looping over x.iter() or x.iter_mut(), could use &x or &mut x
         match method_name {
             "iter" | "iter_mut" => explicit_iter_loop::check(cx, self_arg, arg, method_name),

clippy_lints/src/loops/needless_collect.rs

@@ -31,7 +31,7 @@ fn check_needless_collect_direct_usage<'tcx>(expr: &'tcx Expr<'_>, cx: &LateCont
             let ty = cx.typeck_results().expr_ty(&args[0]);
             let mut applicability = Applicability::MaybeIncorrect;
             let is_empty_sugg = "next().is_none()".to_string();
-            let method_name = &*method.ident.name.as_str();
+            let method_name = method.ident.name.as_str();
             let sugg = if is_type_diagnostic_item(cx, ty, sym::Vec) ||
                         is_type_diagnostic_item(cx, ty, sym::VecDeque) ||
                         is_type_diagnostic_item(cx, ty, sym::LinkedList) ||
@@ -210,7 +210,7 @@ impl<'tcx> Visitor<'tcx> for IterFunctionVisitor<'_, 'tcx> {
                     if let Some(hir_id) = self.current_statement_hir_id {
                         self.hir_id_uses_map.insert(hir_id, self.uses.len());
                     }
-                    match &*method_name.ident.name.as_str() {
+                    match method_name.ident.name.as_str() {
                         "into_iter" => self.uses.push(Some(IterFunction {
                             func: IterFunctionKind::IntoIter,
                             span: expr.span,

clippy_lints/src/match_str_case_mismatch.rs

@@ -9,7 +9,7 @@ use rustc_middle::hir::map::Map;
 use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::symbol::SymbolStr;
+use rustc_span::symbol::Symbol;
 use rustc_span::{sym, Span};
 
 declare_clippy_lint! {
@@ -71,8 +71,8 @@ impl LateLintPass<'_> for MatchStrCaseMismatch {
                 visitor.visit_expr(match_expr);
 
                 if let Some(case_method) = visitor.case_method {
-                    if let Some((bad_case_span, bad_case_str)) = verify_case(&case_method, arms) {
-                        lint(cx, &case_method, bad_case_span, &bad_case_str);
+                    if let Some((bad_case_span, bad_case_sym)) = verify_case(&case_method, arms) {
+                        lint(cx, &case_method, bad_case_span, bad_case_sym.as_str());
                     }
                 }
             }
@@ -95,7 +95,7 @@ impl<'a, 'tcx> Visitor<'tcx> for MatchExprVisitor<'a, 'tcx> {
     fn visit_expr(&mut self, ex: &'tcx Expr<'_>) {
         match ex.kind {
             ExprKind::MethodCall(segment, _, [receiver], _)
-                if self.case_altered(&*segment.ident.as_str(), receiver) => {},
+                if self.case_altered(segment.ident.as_str(), receiver) => {},
             _ => walk_expr(self, ex),
         }
     }
@@ -126,7 +126,7 @@ fn get_case_method(segment_ident_str: &str) -> Option<CaseMethod> {
     }
 }
 
-fn verify_case<'a>(case_method: &'a CaseMethod, arms: &'a [Arm<'_>]) -> Option<(Span, SymbolStr)> {
+fn verify_case<'a>(case_method: &'a CaseMethod, arms: &'a [Arm<'_>]) -> Option<(Span, Symbol)> {
     let case_check = match case_method {
         CaseMethod::LowerCase => |input: &str| -> bool { input.chars().all(|c| c.to_lowercase().next() == Some(c)) },
         CaseMethod::AsciiLowerCase => |input: &str| -> bool { !input.chars().any(|c| c.is_ascii_uppercase()) },
@@ -144,7 +144,7 @@ fn verify_case<'a>(case_method: &'a CaseMethod, arms: &'a [Arm<'_>]) -> Option<(
             let input = symbol.as_str();
             if !case_check(&input);
             then {
-                return Some((lit.span, input));
+                return Some((lit.span, symbol));
             }
         }
     }

clippy_lints/src/matches.rs

@@ -966,7 +966,7 @@ fn check_wild_err_arm<'tcx>(cx: &LateContext<'tcx>, ex: &Expr<'tcx>, arms: &[Arm
                         for pat in inner.iter() {
                             if let PatKind::Binding(_, id, ident, None) = pat.kind {
                                 if ident.as_str().starts_with('_') && !is_local_used(cx, arm.body, id) {
-                                    ident_bind_name = (&ident.name.as_str()).to_string();
+                                    ident_bind_name = ident.name.as_str().to_string();
                                     matching_wild = true;
                                 }
                             }
@@ -1127,7 +1127,7 @@ fn check_wild_enum_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>])
             if let CommonPrefixSearcher::Path(path_prefix) = path_prefix {
                 let mut s = String::new();
                 for seg in path_prefix {
-                    s.push_str(&seg.ident.as_str());
+                    s.push_str(seg.ident.as_str());
                     s.push_str("::");
                 }
                 s

clippy_lints/src/methods/manual_saturating_arithmetic.rs

@@ -81,7 +81,7 @@ fn is_min_or_max<'tcx>(cx: &LateContext<'tcx>, expr: &hir::Expr<'_>) -> Option<M
         if args.is_empty();
         if let hir::ExprKind::Path(hir::QPath::TypeRelative(_, segment)) = &func.kind;
         then {
-            match &*segment.ident.as_str() {
+            match segment.ident.as_str() {
                 "max_value" => return Some(MinMax::Max),
                 "min_value" => return Some(MinMax::Min),
                 _ => {}

clippy_lints/src/methods/mod.rs

@@ -80,7 +80,7 @@ use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::{self, TraitRef, Ty, TyS};
 use rustc_semver::RustcVersion;
 use rustc_session::{declare_tool_lint, impl_lint_pass};
-use rustc_span::symbol::SymbolStr;
+use rustc_span::symbol::Symbol;
 use rustc_span::{sym, Span};
 use rustc_typeck::hir_ty_to_ty;
 
@@ -1997,21 +1997,21 @@ impl_lint_pass!(Methods => [
 ]);
 
 /// Extracts a method call name, args, and `Span` of the method name.
-fn method_call<'tcx>(recv: &'tcx hir::Expr<'tcx>) -> Option<(SymbolStr, &'tcx [hir::Expr<'tcx>], Span)> {
+fn method_call<'tcx>(recv: &'tcx hir::Expr<'tcx>) -> Option<(Symbol, &'tcx [hir::Expr<'tcx>], Span)> {
     if let ExprKind::MethodCall(path, span, args, _) = recv.kind {
         if !args.iter().any(|e| e.span.from_expansion()) {
-            return Some((path.ident.name.as_str(), args, span));
+            return Some((path.ident.name, args, span));
         }
     }
     None
 }
 
-/// Same as `method_call` but the `SymbolStr` is dereferenced into a temporary `&str`
+/// Same as `method_call` but the `Symbol` is dereferenced into a temporary `&str`
 macro_rules! method_call {
     ($expr:expr) => {
         method_call($expr)
             .as_ref()
-            .map(|&(ref name, args, span)| (&**name, args, span))
+            .map(|&(ref name, args, span)| (name.as_str(), args, span))
     };
 }
 
@@ -2028,8 +2028,8 @@ impl<'tcx> LateLintPass<'tcx> for Methods {
                 from_iter_instead_of_collect::check(cx, expr, args, func);
             },
             hir::ExprKind::MethodCall(method_call, ref method_span, args, _) => {
-                or_fun_call::check(cx, expr, *method_span, &method_call.ident.as_str(), args);
-                expect_fun_call::check(cx, expr, *method_span, &method_call.ident.as_str(), args);
+                or_fun_call::check(cx, expr, *method_span, method_call.ident.as_str(), args);
+                expect_fun_call::check(cx, expr, *method_span, method_call.ident.as_str(), args);
                 clone_on_copy::check(cx, expr, method_call.ident.name, args);
                 clone_on_ref_ptr::check(cx, expr, method_call.ident.name, args);
                 inefficient_to_string::check(cx, expr, method_call.ident.name, args);
@@ -2184,7 +2184,7 @@ impl<'tcx> LateLintPass<'tcx> for Methods {
                 let self_ty = TraitRef::identity(cx.tcx, item.def_id.to_def_id()).self_ty().skip_binder();
                 wrong_self_convention::check(
                     cx,
-                    &item.ident.name.as_str(),
+                    item.ident.name.as_str(),
                     self_ty,
                     first_arg_ty,
                     first_arg_span,

clippy_lints/src/methods/str_splitn.rs

@@ -140,7 +140,7 @@ fn parse_iter_usage(
             let did = cx.typeck_results().type_dependent_def_id(e.hir_id)?;
             let iter_id = cx.tcx.get_diagnostic_item(sym::Iterator)?;
 
-            match (&*name.ident.as_str(), args) {
+            match (name.ident.as_str(), args) {
                 ("next", []) if cx.tcx.trait_of_item(did) == Some(iter_id) => {
                     if reverse {
                         (IterUsageKind::Second, e.span)
@@ -298,7 +298,7 @@ fn check_iter(
                 if let Some(did) = cx.typeck_results().type_dependent_def_id(e.hir_id);
                 if let Some(iter_id) = cx.tcx.get_diagnostic_item(sym::Iterator);
                 then {
-                    match (&*name.ident.as_str(), args) {
+                    match (name.ident.as_str(), args) {
                         ("next", []) if cx.tcx.trait_of_item(did) == Some(iter_id) => {
                             return true;
                         },

clippy_lints/src/misc.rs

@@ -407,6 +407,7 @@ impl<'tcx> LateLintPass<'tcx> for MiscLints {
             // Don't lint things expanded by #[derive(...)], etc or `await` desugaring
             return;
         }
+        let sym;
         let binding = match expr.kind {
             ExprKind::Path(ref qpath) if !matches!(qpath, hir::QPath::LangItem(..)) => {
                 let binding = last_path_segment(qpath).ident.as_str();
@@ -423,7 +424,8 @@ impl<'tcx> LateLintPass<'tcx> for MiscLints {
                 }
             },
             ExprKind::Field(_, ident) => {
-                let name = ident.as_str();
+                sym = ident.name;
+                let name = sym.as_str();
                 if name.starts_with('_') && !name.starts_with("__") {
                     Some(name)
                 } else {

clippy_lints/src/missing_enforced_import_rename.rs

@@ -75,7 +75,7 @@ impl LateLintPass<'_> for ImportRename {
             if let Some(import) = match snip.split_once(" as ") {
                 None => Some(snip.as_str()),
                 Some((import, rename)) => {
-                    if rename.trim() == &*name.as_str() {
+                    if rename.trim() == name.as_str() {
                         None
                     } else {
                         Some(import.trim())

clippy_lints/src/multiple_crate_versions.rs

@@ -48,15 +48,15 @@ impl LateLintPass<'_> for MultipleCrateVersions {
         }
 
         let metadata = unwrap_cargo_metadata!(cx, MULTIPLE_CRATE_VERSIONS, true);
-        let local_name = cx.tcx.crate_name(LOCAL_CRATE).as_str();
+        let local_name = cx.tcx.crate_name(LOCAL_CRATE);
         let mut packages = metadata.packages;
         packages.sort_by(|a, b| a.name.cmp(&b.name));
 
         if_chain! {
             if let Some(resolve) = &metadata.resolve;
             if let Some(local_id) = packages
                 .iter()
-                .find_map(|p| if p.name == *local_name { Some(&p.id) } else { None });
+                .find_map(|p| if p.name == local_name.as_str() { Some(&p.id) } else { None });
             then {
                 for (name, group) in &packages.iter().group_by(|p| p.name.clone()) {
                     let group: Vec<&Package> = group.collect();

clippy_lints/src/mut_reference.rs

@@ -49,7 +49,7 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryMutPassed {
                 let def_id = cx.typeck_results().type_dependent_def_id(e.hir_id).unwrap();
                 let substs = cx.typeck_results().node_substs(e.hir_id);
                 let method_type = cx.tcx.type_of(def_id).subst(cx.tcx, substs);
-                check_arguments(cx, arguments, method_type, &path.ident.as_str(), "method");
+                check_arguments(cx, arguments, method_type, path.ident.as_str(), "method");
             },
             _ => (),
         }