more clippy fixes

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -541,15 +541,13 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
             ast::ExprKind::TryBlock(_) => {
                 gate_feature_post!(&self, try_blocks, e.span, "`try` expression is experimental");
             }
-            ast::ExprKind::Block(_, opt_label) => {
-                if let Some(label) = opt_label {
-                    gate_feature_post!(
-                        &self,
-                        label_break_value,
-                        label.ident.span,
-                        "labels on blocks are unstable"
-                    );
-                }
+            ast::ExprKind::Block(_, Some(label)) => {
+                gate_feature_post!(
+                    &self,
+                    label_break_value,
+                    label.ident.span,
+                    "labels on blocks are unstable"
+                );
             }
             _ => {}
         }

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1405,11 +1405,7 @@ impl<'a> State<'a> {
         }
     }
 
-    crate fn print_record_struct_body(
-        &mut self,
-        fields: &Vec<ast::FieldDef>,
-        span: rustc_span::Span,
-    ) {
+    crate fn print_record_struct_body(&mut self, fields: &[ast::FieldDef], span: rustc_span::Span) {
         self.nbsp();
         self.bopen();
         self.hardbreak_if_not_bol();

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -655,7 +655,7 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
             // If the region is live at at least one location in the promoted MIR,
             // then add a liveness constraint to the main MIR for this region
             // at the location provided as an argument to this method
-            if let Some(_) = liveness_constraints.get_elements(region).next() {
+            if liveness_constraints.get_elements(region).next().is_some() {
                 self.cx
                     .borrowck_context
                     .constraints

compiler/rustc_builtin_macros/src/asm.rs

@@ -547,7 +547,7 @@ fn expand_preparsed_asm(ecx: &mut ExtCtxt<'_>, args: AsmArgs) -> Option<ast::Inl
                 if let Some(snippet) = &template_snippet {
                     if let Some(pos) = snippet.find(needle) {
                         let end = pos
-                            + &snippet[pos..]
+                            + snippet[pos..]
                                 .find(|c| matches!(c, '\n' | ';' | '\\' | '"'))
                                 .unwrap_or(snippet[pos..].len() - 1);
                         let inner = InnerSpan::new(pos, end);

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -1095,10 +1095,10 @@ fn add_sanitizer_libraries(sess: &Session, crate_type: CrateType, linker: &mut d
 }
 
 fn link_sanitizer_runtime(sess: &Session, linker: &mut dyn Linker, name: &str) {
-    fn find_sanitizer_runtime(sess: &Session, filename: &String) -> PathBuf {
+    fn find_sanitizer_runtime(sess: &Session, filename: &str) -> PathBuf {
         let session_tlib =
             filesearch::make_target_lib_path(&sess.sysroot, sess.opts.target_triple.triple());
-        let path = session_tlib.join(&filename);
+        let path = session_tlib.join(filename);
         if path.exists() {
             return session_tlib;
         } else {

compiler/rustc_data_structures/src/steal.rs

@@ -34,7 +34,7 @@ impl<T> Steal<T> {
     #[track_caller]
     pub fn borrow(&self) -> MappedReadGuard<'_, T> {
         let borrow = self.value.borrow();
-        if let None = &*borrow {
+        if borrow.is_none() {
             panic!("attempted to read from stolen value: {}", std::any::type_name::<T>());
         }
         ReadGuard::map(borrow, |opt| opt.as_ref().unwrap())

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

@@ -1466,7 +1466,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                     let mut returned_async_output_error = false;
                     for &sp in values {
                         if sp.is_desugaring(DesugaringKind::Async) && !returned_async_output_error {
-                            if &[sp] != err.span.primary_spans() {
+                            if [sp] != err.span.primary_spans() {
                                 let mut span: MultiSpan = sp.into();
                                 span.push_span_label(
                                     sp,

compiler/rustc_interface/src/passes.rs

@@ -47,7 +47,7 @@ use std::ffi::OsString;
 use std::io::{self, BufWriter, Write};
 use std::lazy::SyncLazy;
 use std::marker::PhantomPinned;
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use std::pin::Pin;
 use std::rc::Rc;
 use std::{env, fs, iter};
@@ -536,7 +536,7 @@ where
     None
 }
 
-fn output_contains_path(output_paths: &[PathBuf], input_path: &PathBuf) -> bool {
+fn output_contains_path(output_paths: &[PathBuf], input_path: &Path) -> bool {
     let input_path = input_path.canonicalize().ok();
     if input_path.is_none() {
         return false;
@@ -552,7 +552,7 @@ fn output_conflicts_with_dir(output_paths: &[PathBuf]) -> Option<PathBuf> {
     check_output(output_paths, check)
 }
 
-fn escape_dep_filename(filename: &String) -> String {
+fn escape_dep_filename(filename: &str) -> String {
     // Apparently clang and gcc *only* escape spaces:
     // https://llvm.org/klaus/clang/commit/9d50634cfc268ecc9a7250226dd5ca0e945240d4
     filename.replace(" ", "\\ ")

compiler/rustc_lint/src/builtin.rs

@@ -3130,18 +3130,13 @@ impl<'tcx> LateLintPass<'tcx> for DerefNullPtr {
             false
         }
 
-        if let rustc_hir::ExprKind::Unary(ref un_op, ref expr_deref) = expr.kind {
-            if let rustc_hir::UnOp::Deref = un_op {
-                if is_null_ptr(cx, expr_deref) {
-                    cx.struct_span_lint(DEREF_NULLPTR, expr.span, |lint| {
-                        let mut err = lint.build("dereferencing a null pointer");
-                        err.span_label(
-                            expr.span,
-                            "this code causes undefined behavior when executed",
-                        );
-                        err.emit();
-                    });
-                }
+        if let rustc_hir::ExprKind::Unary(rustc_hir::UnOp::Deref, expr_deref) = expr.kind {
+            if is_null_ptr(cx, expr_deref) {
+                cx.struct_span_lint(DEREF_NULLPTR, expr.span, |lint| {
+                    let mut err = lint.build("dereferencing a null pointer");
+                    err.span_label(expr.span, "this code causes undefined behavior when executed");
+                    err.emit();
+                });
             }
         }
     }
@@ -3196,7 +3191,7 @@ impl<'tcx> LateLintPass<'tcx> for NamedAsmLabels {
                         let snippet = template_snippet.as_str();
                         if let Some(pos) = snippet.find(needle) {
                             let end = pos
-                                + &snippet[pos..]
+                                + snippet[pos..]
                                     .find(|c| c == ':')
                                     .unwrap_or(snippet[pos..].len() - 1);
                             let inner = InnerSpan::new(pos, end);

compiler/rustc_lint/src/internal.rs

@@ -101,33 +101,31 @@ impl<'tcx> LateLintPass<'tcx> for TyTyKind {
 
     fn check_ty(&mut self, cx: &LateContext<'_>, ty: &'tcx Ty<'tcx>) {
         match &ty.kind {
-            TyKind::Path(qpath) => {
-                if let QPath::Resolved(_, path) = qpath {
-                    if let Some(last) = path.segments.iter().last() {
-                        if lint_ty_kind_usage(cx, last) {
-                            cx.struct_span_lint(USAGE_OF_TY_TYKIND, path.span, |lint| {
-                                lint.build("usage of `ty::TyKind`")
-                                    .help("try using `Ty` instead")
-                                    .emit();
-                            })
-                        } else {
-                            if ty.span.from_expansion() {
-                                return;
-                            }
-                            if let Some(t) = is_ty_or_ty_ctxt(cx, ty) {
-                                if path.segments.len() > 1 {
-                                    cx.struct_span_lint(USAGE_OF_QUALIFIED_TY, path.span, |lint| {
-                                        lint.build(&format!("usage of qualified `ty::{}`", t))
-                                            .span_suggestion(
-                                                path.span,
-                                                "try using it unqualified",
-                                                t,
-                                                // The import probably needs to be changed
-                                                Applicability::MaybeIncorrect,
-                                            )
-                                            .emit();
-                                    })
-                                }
+            TyKind::Path(QPath::Resolved(_, path)) => {
+                if let Some(last) = path.segments.iter().last() {
+                    if lint_ty_kind_usage(cx, last) {
+                        cx.struct_span_lint(USAGE_OF_TY_TYKIND, path.span, |lint| {
+                            lint.build("usage of `ty::TyKind`")
+                                .help("try using `Ty` instead")
+                                .emit();
+                        })
+                    } else {
+                        if ty.span.from_expansion() {
+                            return;
+                        }
+                        if let Some(t) = is_ty_or_ty_ctxt(cx, ty) {
+                            if path.segments.len() > 1 {
+                                cx.struct_span_lint(USAGE_OF_QUALIFIED_TY, path.span, |lint| {
+                                    lint.build(&format!("usage of qualified `ty::{}`", t))
+                                        .span_suggestion(
+                                            path.span,
+                                            "try using it unqualified",
+                                            t,
+                                            // The import probably needs to be changed
+                                            Applicability::MaybeIncorrect,
+                                        )
+                                        .emit();
+                                })
                             }
                         }
                     }
@@ -169,37 +167,30 @@ fn lint_ty_kind_usage(cx: &LateContext<'_>, segment: &PathSegment<'_>) -> bool {
 }
 
 fn is_ty_or_ty_ctxt(cx: &LateContext<'_>, ty: &Ty<'_>) -> Option<String> {
-    if let TyKind::Path(qpath) = &ty.kind {
-        if let QPath::Resolved(_, path) = qpath {
-            match path.res {
-                Res::Def(_, def_id) => {
-                    if let Some(name @ (sym::Ty | sym::TyCtxt)) = cx.tcx.get_diagnostic_name(def_id)
-                    {
-                        return Some(format!(
-                            "{}{}",
-                            name,
-                            gen_args(path.segments.last().unwrap())
-                        ));
-                    }
+    if let TyKind::Path(QPath::Resolved(_, path)) = &ty.kind {
+        match path.res {
+            Res::Def(_, def_id) => {
+                if let Some(name @ (sym::Ty | sym::TyCtxt)) = cx.tcx.get_diagnostic_name(def_id) {
+                    return Some(format!("{}{}", name, gen_args(path.segments.last().unwrap())));
                 }
-                // Only lint on `&Ty` and `&TyCtxt` if it is used outside of a trait.
-                Res::SelfTy(None, Some((did, _))) => {
-                    if let ty::Adt(adt, substs) = cx.tcx.type_of(did).kind() {
-                        if let Some(name @ (sym::Ty | sym::TyCtxt)) =
-                            cx.tcx.get_diagnostic_name(adt.did)
-                        {
-                            // NOTE: This path is currently unreachable as `Ty<'tcx>` is
-                            // defined as a type alias meaning that `impl<'tcx> Ty<'tcx>`
-                            // is not actually allowed.
-                            //
-                            // I(@lcnr) still kept this branch in so we don't miss this
-                            // if we ever change it in the future.
-                            return Some(format!("{}<{}>", name, substs[0]));
-                        }
+            }
+            // Only lint on `&Ty` and `&TyCtxt` if it is used outside of a trait.
+            Res::SelfTy(None, Some((did, _))) => {
+                if let ty::Adt(adt, substs) = cx.tcx.type_of(did).kind() {
+                    if let Some(name @ (sym::Ty | sym::TyCtxt)) =
+                        cx.tcx.get_diagnostic_name(adt.did)
+                    {
+                        // NOTE: This path is currently unreachable as `Ty<'tcx>` is
+                        // defined as a type alias meaning that `impl<'tcx> Ty<'tcx>`
+                        // is not actually allowed.
+                        //
+                        // I(@lcnr) still kept this branch in so we don't miss this
+                        // if we ever change it in the future.
+                        return Some(format!("{}<{}>", name, substs[0]));
                     }
                 }
-                _ => (),
             }
+            _ => (),
         }
     }
 

compiler/rustc_macros/src/hash_stable.rs

@@ -24,11 +24,9 @@ fn parse_attributes(field: &syn::Field) -> Attributes {
                         }
                         if meta.path().is_ident("project") {
                             if let Meta::List(list) = meta {
-                                if let Some(nested) = list.nested.iter().next() {
-                                    if let NestedMeta::Meta(meta) = nested {
-                                        attrs.project = meta.path().get_ident().cloned();
-                                        any_attr = true;
-                                    }
+                                if let Some(NestedMeta::Meta(meta)) = list.nested.iter().next() {
+                                    attrs.project = meta.path().get_ident().cloned();
+                                    any_attr = true;
                                 }
                             }
                         }

compiler/rustc_metadata/src/native_libs.rs

@@ -309,7 +309,7 @@ impl Collector<'tcx> {
                     .libs
                     .iter()
                     .filter_map(|lib| lib.name.as_ref())
-                    .any(|n| &n.as_str() == &lib.name);
+                    .any(|n| n.as_str() == lib.name);
                 if new_name.is_empty() {
                     self.tcx.sess.err(&format!(
                         "an empty renaming target was specified for library `{}`",

compiler/rustc_passes/src/check_const.rs

@@ -210,10 +210,10 @@ impl<'tcx> CheckConstVisitor<'tcx> {
             required_gates.iter().copied().filter(|&g| !features.enabled(g)).collect();
 
         match missing_gates.as_slice() {
-            &[] => struct_span_err!(tcx.sess, span, E0744, "{}", msg).emit(),
+            [] => struct_span_err!(tcx.sess, span, E0744, "{}", msg).emit(),
 
-            &[missing_primary, ref missing_secondary @ ..] => {
-                let mut err = feature_err(&tcx.sess.parse_sess, missing_primary, span, &msg);
+            [missing_primary, ref missing_secondary @ ..] => {
+                let mut err = feature_err(&tcx.sess.parse_sess, *missing_primary, span, &msg);
 
                 // If multiple feature gates would be required to enable this expression, include
                 // them as help messages. Don't emit a separate error for each missing feature gate.

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1346,12 +1346,10 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
         } else {
             // Search in module.
             let mod_path = &path[..path.len() - 1];
-            if let PathResult::Module(module) =
+            if let PathResult::Module(ModuleOrUniformRoot::Module(module)) =
                 self.resolve_path(mod_path, Some(TypeNS), false, span, CrateLint::No)
             {
-                if let ModuleOrUniformRoot::Module(module) = module {
-                    self.r.add_module_candidates(module, &mut names, &filter_fn);
-                }
+                self.r.add_module_candidates(module, &mut names, &filter_fn);
             }
         }
 

compiler/rustc_resolve/src/late/lifetimes.rs

@@ -1931,20 +1931,18 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                             break;
                         }
                     }
-                    hir::TyKind::Path(ref qpath) => {
-                        if let QPath::Resolved(_, path) = qpath {
-                            let last_segment = &path.segments[path.segments.len() - 1];
-                            let generics = last_segment.args();
-                            for arg in generics.args.iter() {
-                                if let GenericArg::Lifetime(lt) = arg {
-                                    if lt.name.ident() == name {
-                                        elide_use = Some(lt.span);
-                                        break;
-                                    }
+                    hir::TyKind::Path(QPath::Resolved(_, path)) => {
+                        let last_segment = &path.segments[path.segments.len() - 1];
+                        let generics = last_segment.args();
+                        for arg in generics.args.iter() {
+                            if let GenericArg::Lifetime(lt) = arg {
+                                if lt.name.ident() == name {
+                                    elide_use = Some(lt.span);
+                                    break;
                                 }
                             }
-                            break;
                         }
+                        break;
                     }
                     _ => {}
                 }

compiler/rustc_session/src/config.rs

@@ -914,7 +914,7 @@ pub fn build_configuration(sess: &Session, mut user_cfg: CrateConfig) -> CrateCo
 pub(super) fn build_target_config(
     opts: &Options,
     target_override: Option<Target>,
-    sysroot: &PathBuf,
+    sysroot: &Path,
 ) -> Target {
     let target_result = target_override.map_or_else(
         || Target::search(&opts.target_triple, sysroot),

compiler/rustc_session/src/options.rs

@@ -881,7 +881,7 @@ mod parse {
         match v {
             Some(s) => {
                 if !slot.is_empty() {
-                    slot.push_str(",");
+                    slot.push(',');
                 }
                 slot.push_str(s);
                 true

compiler/rustc_span/src/lib.rs

@@ -194,10 +194,8 @@ impl<S: Encoder> Encodable<S> for RealFileName {
         encoder.emit_enum(|encoder| match *self {
             RealFileName::LocalPath(ref local_path) => {
                 encoder.emit_enum_variant("LocalPath", 0, 1, |encoder| {
-                    Ok({
-                        encoder
-                            .emit_enum_variant_arg(true, |encoder| local_path.encode(encoder))?;
-                    })
+                    encoder.emit_enum_variant_arg(true, |encoder| local_path.encode(encoder))?;
+                    Ok(())
                 })
             }
 
@@ -206,12 +204,9 @@ impl<S: Encoder> Encodable<S> for RealFileName {
                     // For privacy and build reproducibility, we must not embed host-dependant path in artifacts
                     // if they have been remapped by --remap-path-prefix
                     assert!(local_path.is_none());
-                    Ok({
-                        encoder
-                            .emit_enum_variant_arg(true, |encoder| local_path.encode(encoder))?;
-                        encoder
-                            .emit_enum_variant_arg(false, |encoder| virtual_name.encode(encoder))?;
-                    })
+                    encoder.emit_enum_variant_arg(true, |encoder| local_path.encode(encoder))?;
+                    encoder.emit_enum_variant_arg(false, |encoder| virtual_name.encode(encoder))?;
+                    Ok(())
                 }),
         })
     }