Use a slice where a vector is not necessary

src/librustc/hir/lowering.rs

@@ -746,7 +746,7 @@ impl<'a> LoweringContext<'a> {
     // This is used to track which lifetimes have already been defined, and
     // which are new in-band lifetimes that need to have a definition created
     // for them.
-    fn with_in_scope_lifetime_defs<T, F>(&mut self, params: &Vec<GenericParam>, f: F) -> T
+    fn with_in_scope_lifetime_defs<T, F>(&mut self, params: &[GenericParam], f: F) -> T
     where
         F: FnOnce(&mut LoweringContext) -> T,
     {
@@ -2237,7 +2237,7 @@ impl<'a> LoweringContext<'a> {
 
     fn lower_generic_params(
         &mut self,
-        params: &Vec<GenericParam>,
+        params: &[GenericParam],
         add_bounds: &NodeMap<Vec<GenericBound>>,
         mut itctx: ImplTraitContext,
     ) -> hir::HirVec<hir::GenericParam> {

src/librustc/ich/hcx.rs

@@ -396,7 +396,7 @@ impl<'a> HashStable<StableHashingContext<'a>> for Span {
 pub fn hash_stable_trait_impls<'a, 'gcx, W, R>(
     hcx: &mut StableHashingContext<'a>,
     hasher: &mut StableHasher<W>,
-    blanket_impls: &Vec<DefId>,
+    blanket_impls: &[DefId],
     non_blanket_impls: &HashMap<fast_reject::SimplifiedType, Vec<DefId>, R>)
     where W: StableHasherResult,
           R: std_hash::BuildHasher,

src/librustc/traits/error_reporting.rs

@@ -48,7 +48,7 @@ use syntax_pos::{DUMMY_SP, Span};
 
 impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
     pub fn report_fulfillment_errors(&self,
-                                     errors: &Vec<FulfillmentError<'tcx>>,
+                                     errors: &[FulfillmentError<'tcx>],
                                      body_id: Option<hir::BodyId>,
                                      fallback_has_occurred: bool) {
         #[derive(Debug)]
@@ -1015,7 +1015,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
     ) -> DiagnosticBuilder<'tcx> {
         let kind = if is_closure { "closure" } else { "function" };
 
-        let args_str = |arguments: &Vec<ArgKind>, other: &Vec<ArgKind>| {
+        let args_str = |arguments: &[ArgKind], other: &[ArgKind]| {
             let arg_length = arguments.len();
             let distinct = match &other[..] {
                 &[ArgKind::Tuple(..)] => true,

src/librustc_borrowck/borrowck/gather_loans/move_error.rs

@@ -68,7 +68,7 @@ pub struct GroupedMoveErrors<'tcx> {
     move_to_places: Vec<MovePlace<'tcx>>
 }
 
-fn report_move_errors<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>, errors: &Vec<MoveError<'tcx>>) {
+fn report_move_errors<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>, errors: &[MoveError<'tcx>]) {
     let grouped_errors = group_errors_with_same_origin(errors);
     for error in &grouped_errors {
         let mut err = report_cannot_move_out_of(bccx, error.move_from.clone());
@@ -103,7 +103,7 @@ fn report_move_errors<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>, errors: &Vec<Move
     }
 }
 
-fn group_errors_with_same_origin<'tcx>(errors: &Vec<MoveError<'tcx>>)
+fn group_errors_with_same_origin<'tcx>(errors: &[MoveError<'tcx>])
                                        -> Vec<GroupedMoveErrors<'tcx>> {
     let mut grouped_errors = Vec::new();
     for error in errors {

src/librustc_driver/driver.rs

@@ -1395,7 +1395,7 @@ fn generated_output_paths(
 
 // Runs `f` on every output file path and returns the first non-None result, or None if `f`
 // returns None for every file path.
-fn check_output<F, T>(output_paths: &Vec<PathBuf>, f: F) -> Option<T>
+fn check_output<F, T>(output_paths: &[PathBuf], f: F) -> Option<T>
 where
     F: Fn(&PathBuf) -> Option<T>,
 {
@@ -1407,7 +1407,7 @@ where
     None
 }
 
-pub fn output_contains_path(output_paths: &Vec<PathBuf>, input_path: &PathBuf) -> bool {
+pub fn output_contains_path(output_paths: &[PathBuf], input_path: &PathBuf) -> bool {
     let input_path = input_path.canonicalize().ok();
     if input_path.is_none() {
         return false;
@@ -1422,7 +1422,7 @@ pub fn output_contains_path(output_paths: &Vec<PathBuf>, input_path: &PathBuf) -
     check_output(output_paths, check).is_some()
 }
 
-pub fn output_conflicts_with_dir(output_paths: &Vec<PathBuf>) -> Option<PathBuf> {
+pub fn output_conflicts_with_dir(output_paths: &[PathBuf]) -> Option<PathBuf> {
     let check = |output_path: &PathBuf| {
         if output_path.is_dir() {
             Some(output_path.clone())
@@ -1433,7 +1433,7 @@ pub fn output_conflicts_with_dir(output_paths: &Vec<PathBuf>) -> Option<PathBuf>
     check_output(output_paths, check)
 }
 
-fn write_out_deps(sess: &Session, outputs: &OutputFilenames, out_filenames: &Vec<PathBuf>) {
+fn write_out_deps(sess: &Session, outputs: &OutputFilenames, out_filenames: &[PathBuf]) {
     // Write out dependency rules to the dep-info file if requested
     if !sess.opts.output_types.contains_key(&OutputType::DepInfo) {
         return;

src/librustc_driver/profile/mod.rs

@@ -62,7 +62,7 @@ struct StackFrame {
     pub traces:   Vec<trace::Rec>,
 }
 
-fn total_duration(traces: &Vec<trace::Rec>) -> Duration {
+fn total_duration(traces: &[trace::Rec]) -> Duration {
     let mut sum : Duration = Duration::new(0,0);
     for t in traces.iter() { sum += t.dur_total; }
     return sum

src/librustc_driver/profile/trace.rs

@@ -107,7 +107,7 @@ fn html_of_fraction(frac: f64) -> (String, String) {
     else { (format!("< 0.1%", ), css) }
 }
 
-fn total_duration(traces: &Vec<Rec>) -> Duration {
+fn total_duration(traces: &[Rec]) -> Duration {
     let mut sum : Duration = Duration::new(0,0);
     for t in traces.iter() {
         sum += t.dur_total;
@@ -123,7 +123,7 @@ fn duration_div(nom: Duration, den: Duration) -> f64 {
     to_nanos(nom) as f64 / to_nanos(den) as f64
 }
 
-fn write_traces_rec(file: &mut File, traces: &Vec<Rec>, total: Duration, depth: usize) {
+fn write_traces_rec(file: &mut File, traces: &[Rec], total: Duration, depth: usize) {
     for t in traces {
         let (eff_text, eff_css_classes) = html_of_effect(&t.effect);
         let (dur_text, dur_css_classes) = html_of_duration(&t.start, &t.dur_total);
@@ -149,7 +149,7 @@ fn write_traces_rec(file: &mut File, traces: &Vec<Rec>, total: Duration, depth:
     }
 }
 
-fn compute_counts_rec(counts: &mut HashMap<String,QueryMetric>, traces: &Vec<Rec>) {
+fn compute_counts_rec(counts: &mut HashMap<String,QueryMetric>, traces: &[Rec]) {
     for t in traces.iter() {
         match t.effect {
             Effect::TimeBegin(ref msg) => {
@@ -218,7 +218,7 @@ pub fn write_counts(count_file: &mut File, counts: &mut HashMap<String,QueryMetr
     }
 }
 
-pub fn write_traces(html_file: &mut File, counts_file: &mut File, traces: &Vec<Rec>) {
+pub fn write_traces(html_file: &mut File, counts_file: &mut File, traces: &[Rec]) {
     let capacity = traces.iter().fold(0, |acc, t| acc + 1 + t.extent.len());
     let mut counts : HashMap<String, QueryMetric> = HashMap::with_capacity(capacity);
     compute_counts_rec(&mut counts, traces);

src/librustc_errors/emitter.rs

@@ -749,7 +749,7 @@ impl EmitterWriter {
         max
     }
 
-    fn get_max_line_num(&mut self, span: &MultiSpan, children: &Vec<SubDiagnostic>) -> usize {
+    fn get_max_line_num(&mut self, span: &MultiSpan, children: &[SubDiagnostic]) -> usize {
         let mut max = 0;
 
         let primary = self.get_multispan_max_line_num(span);
@@ -954,7 +954,7 @@ impl EmitterWriter {
 
     fn emit_message_default(&mut self,
                             msp: &MultiSpan,
-                            msg: &Vec<(String, Style)>,
+                            msg: &[(String, Style)],
                             code: &Option<DiagnosticId>,
                             level: &Level,
                             max_line_num_len: usize,
@@ -1317,10 +1317,10 @@ impl EmitterWriter {
 
     fn emit_messages_default(&mut self,
                              level: &Level,
-                             message: &Vec<(String, Style)>,
+                             message: &[(String, Style)],
                              code: &Option<DiagnosticId>,
                              span: &MultiSpan,
-                             children: &Vec<SubDiagnostic>,
+                             children: &[SubDiagnostic],
                              suggestions: &[CodeSuggestion]) {
         let max_line_num_len = if self.ui_testing {
             ANONYMIZED_LINE_NUM.len()
@@ -1433,7 +1433,7 @@ fn overlaps(a1: &Annotation, a2: &Annotation, padding: usize) -> bool {
     num_overlap(a1.start_col, a1.end_col + padding, a2.start_col, a2.end_col, false)
 }
 
-fn emit_to_destination(rendered_buffer: &Vec<Vec<StyledString>>,
+fn emit_to_destination(rendered_buffer: &[Vec<StyledString>],
                        lvl: &Level,
                        dst: &mut Destination,
                        short_message: bool)

src/librustc_mir/borrow_check/nll/facts.rs

@@ -120,7 +120,7 @@ struct FactWriter<'w> {
 impl<'w> FactWriter<'w> {
     fn write_facts_to_path<T>(
         &self,
-        rows: &Vec<T>,
+        rows: &[T],
         file_name: &str,
     ) -> Result<(), Box<dyn Error>>
     where

src/librustc_mir/interpret/terminator/drop.rs

@@ -78,7 +78,7 @@ impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M> {
         self.eval_fn_call(
             instance,
             Some((Place::undef(), target)),
-            &vec![valty],
+            &[valty],
             span,
             fn_sig,
         )

src/librustc_mir/transform/uniform_array_move_out.rs

@@ -222,7 +222,7 @@ impl RestoreSubsliceArrayMoveOut {
     // indices is an integer interval. If all checks pass do the replacent.
     // items are Vec<Option<LocalUse, index in source array, source place for init local>>
     fn check_and_patch<'tcx>(candidate: Location,
-                             items: &Vec<Option<(&LocalUse, u32, &Place<'tcx>)>>,
+                             items: &[Option<(&LocalUse, u32, &Place<'tcx>)>],
                              opt_size: Option<u64>,
                              patch: &mut MirPatch<'tcx>,
                              dst_place: &Place<'tcx>) {

src/librustc_passes/ast_validation.rs

@@ -147,7 +147,7 @@ impl<'a> AstValidator<'a> {
         }
     }
 
-    fn check_late_bound_lifetime_defs(&self, params: &Vec<GenericParam>) {
+    fn check_late_bound_lifetime_defs(&self, params: &[GenericParam]) {
         // Check only lifetime parameters are present and that the lifetime
         // parameters that are present have no bounds.
         let non_lt_param_spans: Vec<_> = params.iter().filter_map(|param| match param.kind {

src/librustc_resolve/macros.rs

@@ -783,7 +783,7 @@ impl<'a> Resolver<'a> {
                 }
             };
             let ident = Ident::new(Symbol::intern(name), span);
-            self.lookup_typo_candidate(&vec![ident], MacroNS, is_macro, span)
+            self.lookup_typo_candidate(&[ident], MacroNS, is_macro, span)
         });
 
         if let Some(suggestion) = suggestion {

src/librustdoc/html/render.rs

@@ -2690,7 +2690,7 @@ fn render_implementor(cx: &Context, implementor: &Impl, w: &mut fmt::Formatter,
     for it in &implementor.inner_impl().items {
         if let clean::TypedefItem(ref tydef, _) = it.inner {
             write!(w, "<span class=\"where fmt-newline\">  ")?;
-            assoc_type(w, it, &vec![], Some(&tydef.type_), AssocItemLink::Anchor(None))?;
+            assoc_type(w, it, &[], Some(&tydef.type_), AssocItemLink::Anchor(None))?;
             write!(w, ";</span>")?;
         }
     }
@@ -3040,7 +3040,7 @@ fn assoc_const(w: &mut fmt::Formatter,
 }
 
 fn assoc_type<W: fmt::Write>(w: &mut W, it: &clean::Item,
-                             bounds: &Vec<clean::GenericBound>,
+                             bounds: &[clean::GenericBound],
                              default: Option<&clean::Type>,
                              link: AssocItemLink) -> fmt::Result {
     write!(w, "type <a href='{}' class=\"type\">{}</a>",
@@ -3749,7 +3749,7 @@ fn spotlight_decl(decl: &clean::FnDecl) -> Result<String, fmt::Error> {
                     for it in &impl_.items {
                         if let clean::TypedefItem(ref tydef, _) = it.inner {
                             out.push_str("<span class=\"where fmt-newline\">    ");
-                            assoc_type(&mut out, it, &vec![],
+                            assoc_type(&mut out, it, &[],
                                        Some(&tydef.type_),
                                        AssocItemLink::GotoSource(t_did, &FxHashSet()))?;
                             out.push_str(";</span>");

src/libsyntax/print/pprust.rs

@@ -3065,7 +3065,7 @@ impl<'a> State<'a> {
                        unsafety: ast::Unsafety,
                        decl: &ast::FnDecl,
                        name: Option<ast::Ident>,
-                       generic_params: &Vec<ast::GenericParam>)
+                       generic_params: &[ast::GenericParam])
                        -> io::Result<()> {
         self.ibox(INDENT_UNIT)?;
         if !generic_params.is_empty() {