Fix some clippy warnings in libsyntax

src/libsyntax/ast.rs

@@ -715,7 +715,7 @@ impl Stmt {
             StmtKind::Mac(mac) => StmtKind::Mac(mac.map(|(mac, _style, attrs)| {
                 (mac, MacStmtStyle::Semicolon, attrs)
             })),
-            node @ _ => node,
+            node => node,
         };
         self
     }
@@ -1076,16 +1076,16 @@ impl LitKind {
     pub fn is_unsuffixed(&self) -> bool {
         match *self {
             // unsuffixed variants
-            LitKind::Str(..) => true,
-            LitKind::ByteStr(..) => true,
-            LitKind::Byte(..) => true,
-            LitKind::Char(..) => true,
-            LitKind::Int(_, LitIntType::Unsuffixed) => true,
-            LitKind::FloatUnsuffixed(..) => true,
+            LitKind::Str(..) |
+            LitKind::ByteStr(..) |
+            LitKind::Byte(..) |
+            LitKind::Char(..) |
+            LitKind::Int(_, LitIntType::Unsuffixed) |
+            LitKind::FloatUnsuffixed(..) |
             LitKind::Bool(..) => true,
             // suffixed variants
-            LitKind::Int(_, LitIntType::Signed(..)) => false,
-            LitKind::Int(_, LitIntType::Unsigned(..)) => false,
+            LitKind::Int(_, LitIntType::Signed(..)) |
+            LitKind::Int(_, LitIntType::Unsigned(..)) |
             LitKind::Float(..) => false,
         }
     }

src/libsyntax/attr.rs

@@ -112,15 +112,15 @@ impl NestedMetaItem {
     /// Returns the MetaItem if self is a NestedMetaItemKind::MetaItem.
     pub fn meta_item(&self) -> Option<&MetaItem> {
         match self.node {
-            NestedMetaItemKind::MetaItem(ref item) => Some(&item),
+            NestedMetaItemKind::MetaItem(ref item) => Some(item),
             _ => None
         }
     }
 
     /// Returns the Lit if self is a NestedMetaItemKind::Literal.
     pub fn literal(&self) -> Option<&Lit> {
         match self.node {
-            NestedMetaItemKind::Literal(ref lit) => Some(&lit),
+            NestedMetaItemKind::Literal(ref lit) => Some(lit),
             _ => None
         }
     }
@@ -259,7 +259,7 @@ impl MetaItem {
         match self.node {
             MetaItemKind::NameValue(ref v) => {
                 match v.node {
-                    LitKind::Str(ref s, _) => Some((*s).clone()),
+                    LitKind::Str(ref s, _) => Some(*s),
                     _ => None,
                 }
             },
@@ -1217,9 +1217,10 @@ impl LitKind {
                 Token::Literal(token::Lit::Float(symbol), Some(Symbol::intern(ty.ty_to_string())))
             }
             LitKind::FloatUnsuffixed(symbol) => Token::Literal(token::Lit::Float(symbol), None),
-            LitKind::Bool(value) => Token::Ident(Ident::with_empty_ctxt(Symbol::intern(match value {
-                true => "true",
-                false => "false",
+            LitKind::Bool(value) => Token::Ident(Ident::with_empty_ctxt(Symbol::intern(if value {
+                "true"
+            } else {
+                "false"
             }))),
         }
     }
@@ -1261,7 +1262,7 @@ impl<T: HasAttrs> HasAttrs for Spanned<T> {
 
 impl HasAttrs for Vec<Attribute> {
     fn attrs(&self) -> &[Attribute] {
-        &self
+        self
     }
     fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
         f(self)
@@ -1270,7 +1271,7 @@ impl HasAttrs for Vec<Attribute> {
 
 impl HasAttrs for ThinVec<Attribute> {
     fn attrs(&self) -> &[Attribute] {
-        &self
+        self
     }
     fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
         f(self.into()).into()

src/libsyntax/codemap.rs

@@ -485,7 +485,7 @@ impl CodeMap {
         match self.span_to_snippet(sp) {
             Ok(snippet) => {
                 let snippet = snippet.split(c).nth(0).unwrap_or("").trim_right();
-                if snippet.len() > 0 && !snippet.contains('\n') {
+                if !snippet.is_empty() && !snippet.contains('\n') {
                     Span { hi: BytePos(sp.lo.0 + snippet.len() as u32), ..sp }
                 } else {
                     sp
@@ -502,7 +502,7 @@ impl CodeMap {
     pub fn get_filemap(&self, filename: &str) -> Option<Rc<FileMap>> {
         for fm in self.files.borrow().iter() {
             if filename == fm.name {
-               (self.dep_tracking_callback.borrow())(&fm);
+               (self.dep_tracking_callback.borrow())(fm);
                 return Some(fm.clone());
             }
         }

src/libsyntax/config.rs

@@ -123,7 +123,7 @@ impl<'a> StripUnconfigured<'a> {
                 return false;
             }
 
-            let mis = if !is_cfg(&attr) {
+            let mis = if !is_cfg(attr) {
                 return true;
             } else if let Some(mis) = attr.meta_item_list() {
                 mis
@@ -150,7 +150,7 @@ impl<'a> StripUnconfigured<'a> {
         // flag the offending attributes
         for attr in attrs.iter() {
             if !self.features.map(|features| features.stmt_expr_attributes).unwrap_or(true) {
-                let mut err = feature_err(&self.sess,
+                let mut err = feature_err(self.sess,
                                           "stmt_expr_attributes",
                                           attr.span,
                                           GateIssue::Language,
@@ -258,7 +258,7 @@ impl<'a> StripUnconfigured<'a> {
     pub fn configure_struct_expr_field(&mut self, field: ast::Field) -> Option<ast::Field> {
         if !self.features.map(|features| features.struct_field_attributes).unwrap_or(true) {
             if !field.attrs.is_empty() {
-                let mut err = feature_err(&self.sess,
+                let mut err = feature_err(self.sess,
                                           "struct_field_attributes",
                                           field.span,
                                           GateIssue::Language,
@@ -290,7 +290,7 @@ impl<'a> StripUnconfigured<'a> {
         for attr in attrs.iter() {
             if !self.features.map(|features| features.struct_field_attributes).unwrap_or(true) {
                 let mut err = feature_err(
-                    &self.sess,
+                    self.sess,
                     "struct_field_attributes",
                     attr.span,
                     GateIssue::Language,

src/libsyntax/diagnostics/plugin.rs

@@ -120,7 +120,7 @@ pub fn expand_register_diagnostic<'cx>(ecx: &'cx mut ExtCtxt,
 
         // URLs can be unavoidably longer than the line limit, so we allow them.
         // Allowed format is: `[name]: https://www.rust-lang.org/`
-        let is_url = |l: &str| l.starts_with('[') && l.contains("]:") && l.contains("http");
+        let is_url = |l: &str| l.starts_with("[") && l.contains("]:") && l.contains("http");
 
         if msg.lines().any(|line| line.len() > MAX_DESCRIPTION_WIDTH && !is_url(line)) {
             ecx.span_err(span, &format!(
@@ -177,7 +177,7 @@ pub fn expand_build_diagnostic_array<'cx>(ecx: &'cx mut ExtCtxt,
             if let Err(e) = output_metadata(ecx,
                                             &target_triple,
                                             &crate_name.name.as_str(),
-                                            &diagnostics) {
+                                            diagnostics) {
                 ecx.span_bug(span, &format!(
                     "error writing metadata for triple `{}` and crate `{}`, error: {}, \
                      cause: {:?}",
@@ -227,7 +227,7 @@ pub fn expand_build_diagnostic_array<'cx>(ecx: &'cx mut ExtCtxt,
 
     MacEager::items(SmallVector::many(vec![
         P(ast::Item {
-            ident: name.clone(),
+            ident: *name,
             attrs: Vec::new(),
             id: ast::DUMMY_NODE_ID,
             node: ast::ItemKind::Const(

src/libsyntax/ext/base.rs

@@ -635,8 +635,8 @@ pub struct ExpansionData {
 }
 
 /// One of these is made during expansion and incrementally updated as we go;
-/// when a macro expansion occurs, the resulting nodes have the backtrace()
-/// -> expn_info of their expansion context stored into their span.
+/// when a macro expansion occurs, the resulting nodes have the `backtrace()
+/// -> expn_info` of their expansion context stored into their span.
 pub struct ExtCtxt<'a> {
     pub parse_sess: &'a parse::ParseSess,
     pub ecfg: expand::ExpansionConfig<'a>,
@@ -709,7 +709,7 @@ impl<'a> ExtCtxt<'a> {
                 }
                 ctxt = info.call_site.ctxt;
                 last_macro = Some(info.call_site);
-                return Some(());
+                Some(())
             }).is_none() {
                 break
             }
@@ -770,9 +770,9 @@ impl<'a> ExtCtxt<'a> {
     }
     pub fn trace_macros_diag(&self) {
         for (sp, notes) in self.expansions.iter() {
-            let mut db = self.parse_sess.span_diagnostic.span_note_diag(*sp, &"trace_macro");
+            let mut db = self.parse_sess.span_diagnostic.span_note_diag(*sp, "trace_macro");
             for note in notes {
-                db.note(&note);
+                db.note(note);
             }
             db.emit();
         }
@@ -795,7 +795,7 @@ impl<'a> ExtCtxt<'a> {
             v.push(self.ident_of(s));
         }
         v.extend(components.iter().map(|s| self.ident_of(s)));
-        return v
+        v
     }
     pub fn name_of(&self, st: &str) -> ast::Name {
         Symbol::intern(st)

src/libsyntax/ext/expand.rs

@@ -415,19 +415,19 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
 
         match *ext {
             MultiModifier(ref mac) => {
-                let meta = panictry!(attr.parse_meta(&self.cx.parse_sess));
+                let meta = panictry!(attr.parse_meta(self.cx.parse_sess));
                 let item = mac.expand(self.cx, attr.span, &meta, item);
                 kind.expect_from_annotatables(item)
             }
             MultiDecorator(ref mac) => {
                 let mut items = Vec::new();
-                let meta = panictry!(attr.parse_meta(&self.cx.parse_sess));
+                let meta = panictry!(attr.parse_meta(self.cx.parse_sess));
                 mac.expand(self.cx, attr.span, &meta, &item, &mut |item| items.push(item));
                 items.push(item);
                 kind.expect_from_annotatables(items)
             }
             SyntaxExtension::AttrProcMacro(ref mac) => {
-                let item_toks = stream_for_item(&item, &self.cx.parse_sess);
+                let item_toks = stream_for_item(&item, self.cx.parse_sess);
 
                 let span = Span { ctxt: self.cx.backtrace(), ..attr.span };
                 let tok_result = mac.expand(self.cx, attr.span, attr.tokens, item_toks);
@@ -439,7 +439,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             }
             _ => {
                 let msg = &format!("macro `{}` may not be used in attributes", attr.path);
-                self.cx.span_err(attr.span, &msg);
+                self.cx.span_err(attr.span, msg);
                 kind.dummy(attr.span)
             }
         }
@@ -454,7 +454,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         };
         let path = &mac.node.path;
 
-        let ident = ident.unwrap_or(keywords::Invalid.ident());
+        let ident = ident.unwrap_or_else(|| keywords::Invalid.ident());
         let marked_tts = noop_fold_tts(mac.node.stream(), &mut Marker(mark));
         let opt_expanded = match *ext {
             NormalTT(ref expandfun, exp_span, allow_internal_unstable) => {
@@ -591,7 +591,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             }
             _ => {
                 let msg = &format!("macro `{}` may not be used for derive attributes", attr.path);
-                self.cx.span_err(span, &msg);
+                self.cx.span_err(span, msg);
                 kind.dummy(span)
             }
         }
@@ -749,19 +749,15 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
     fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
         let features = self.cx.ecfg.features.unwrap();
         for attr in attrs.iter() {
-            feature_gate::check_attribute(&attr, &self.cx.parse_sess, features);
+            feature_gate::check_attribute(attr, self.cx.parse_sess, features);
         }
     }
 }
 
 pub fn find_attr_invoc(attrs: &mut Vec<ast::Attribute>) -> Option<ast::Attribute> {
-    for i in 0 .. attrs.len() {
-        if !attr::is_known(&attrs[i]) && !is_builtin_attr(&attrs[i]) {
-             return Some(attrs.remove(i));
-        }
-    }
-
-    None
+    attrs.iter()
+         .position(|a| !attr::is_known(a) && !is_builtin_attr(a))
+         .map(|i| attrs.remove(i))
 }
 
 // These are pretty nasty. Ideally, we would keep the tokens around, linked from
@@ -923,7 +919,7 @@ impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
                 let result = noop_fold_item(item, self);
                 self.cx.current_expansion.module = orig_module;
                 self.cx.current_expansion.directory_ownership = orig_directory_ownership;
-                return result;
+                result
             }
             // Ensure that test functions are accessible from the test harness.
             ast::ItemKind::Fn(..) if self.cx.ecfg.should_test => {

src/libsyntax/ext/quote.rs

@@ -23,7 +23,7 @@ use tokenstream::{TokenStream, TokenTree};
 ///
 /// This is registered as a set of expression syntax extension called quote!
 /// that lifts its argument token-tree to an AST representing the
-/// construction of the same token tree, with token::SubstNt interpreted
+/// construction of the same token tree, with `token::SubstNt` interpreted
 /// as antiquotes (splices).
 
 pub mod rt {
@@ -389,7 +389,7 @@ pub fn unflatten(tts: Vec<TokenTree>) -> Vec<TokenTree> {
                 result = results.pop().unwrap();
                 result.push(tree);
             }
-            tree @ _ => result.push(tree),
+            tree => result.push(tree),
         }
     }
     result

src/libsyntax/ext/source_util.rs

@@ -150,7 +150,7 @@ pub fn expand_include_str(cx: &mut ExtCtxt, sp: Span, tts: &[tokenstream::TokenT
             cx.span_err(sp,
                         &format!("{} wasn't a utf-8 file",
                                 file.display()));
-            return DummyResult::expr(sp);
+            DummyResult::expr(sp)
         }
     }
 }
@@ -167,7 +167,7 @@ pub fn expand_include_bytes(cx: &mut ExtCtxt, sp: Span, tts: &[tokenstream::Toke
         Err(e) => {
             cx.span_err(sp,
                         &format!("couldn't read {}: {}", file.display(), e));
-            return DummyResult::expr(sp);
+            DummyResult::expr(sp)
         }
         Ok(..) => {
             // Add this input file to the code map to make it available as