Rollup merge of #62131 - Xanewok:clip-some-nits, r=petrochenkov

libsyntax: Fix some Clippy warnings

When I was working on it before a lot of these popped up in the RLS so I figured I'll send a small patch fixing only the (hopefully) uncontroversial ones.

Others that could be also fixed included also [`clippy::print_with_newline`](https://rust-lang.github.io/rust-clippy/master/index.html#print_with_newline) and [`clippy::cast_lossless`](https://rust-lang.github.io/rust-clippy/master/index.html#cast_lossless). Should I add them as well?

since most of it touches libsyntax...
r? @petrochenkov

src/librustc_data_structures/fingerprint.rs

@@ -39,8 +39,8 @@ impl Fingerprint {
     // you want.
     #[inline]
     pub fn combine_commutative(self, other: Fingerprint) -> Fingerprint {
-        let a = (self.1 as u128) << 64 | self.0 as u128;
-        let b = (other.1 as u128) << 64 | other.0 as u128;
+        let a = u128::from(self.1) << 64 | u128::from(self.0);
+        let b = u128::from(other.1) << 64 | u128::from(other.0);
 
         let c = a.wrapping_add(b);
 

src/librustc_data_structures/obligation_forest/mod.rs

@@ -263,7 +263,7 @@ impl<O: ForestObligation> ObligationForest<O> {
             done_cache: Default::default(),
             waiting_cache: Default::default(),
             scratch: Some(vec![]),
-            obligation_tree_id_generator: (0..).map(|i| ObligationTreeId(i)),
+            obligation_tree_id_generator: (0..).map(ObligationTreeId),
             error_cache: Default::default(),
         }
     }

src/librustc_data_structures/sip128.rs

@@ -70,15 +70,15 @@ unsafe fn u8to64_le(buf: &[u8], start: usize, len: usize) -> u64 {
     let mut i = 0; // current byte index (from LSB) in the output u64
     let mut out = 0;
     if i + 3 < len {
-        out = load_int_le!(buf, start + i, u32) as u64;
+        out = u64::from(load_int_le!(buf, start + i, u32));
         i += 4;
     }
     if i + 1 < len {
-        out |= (load_int_le!(buf, start + i, u16) as u64) << (i * 8);
+        out |= u64::from(load_int_le!(buf, start + i, u16)) << (i * 8);
         i += 2
     }
     if i < len {
-        out |= (*buf.get_unchecked(start + i) as u64) << (i * 8);
+        out |= u64::from(*buf.get_unchecked(start + i)) << (i * 8);
         i += 1;
     }
     debug_assert_eq!(i, len);
@@ -237,7 +237,7 @@ impl Hasher for SipHasher128 {
 
         if self.ntail != 0 {
             needed = 8 - self.ntail;
-            self.tail |= unsafe { u8to64_le(msg, 0, cmp::min(length, needed)) } << 8 * self.ntail;
+            self.tail |= unsafe { u8to64_le(msg, 0, cmp::min(length, needed)) } << (8 * self.ntail);
             if length < needed {
                 self.ntail += length;
                 return

src/librustc_data_structures/stable_hasher.rs

@@ -44,7 +44,7 @@ impl<W: StableHasherResult> StableHasher<W> {
 impl StableHasherResult for u128 {
     fn finish(hasher: StableHasher<Self>) -> Self {
         let (_0, _1) = hasher.finalize();
-        (_0 as u128) | ((_1 as u128) << 64)
+        u128::from(_0) | (u128::from(_1) << 64)
     }
 }
 

src/librustc_data_structures/vec_linked_list.rs

@@ -8,7 +8,7 @@ where
     Ls: Links,
 {
     VecLinkedListIterator {
-        links: links,
+        links,
         current: first,
     }
 }

src/librustc_errors/annotate_snippet_emitter_writer.rs

@@ -94,7 +94,7 @@ impl<'a>  DiagnosticConverter<'a> {
                     annotation_type: Self::annotation_type_for_level(self.level),
                 }),
                 footer: vec![],
-                slices: slices,
+                slices,
             })
         } else {
             // FIXME(#59346): Is it ok to return None if there's no source_map?

src/librustc_errors/diagnostic.rs

@@ -388,7 +388,7 @@ impl Diagnostic {
             }],
             msg: msg.to_owned(),
             style: SuggestionStyle::CompletelyHidden,
-            applicability: applicability,
+            applicability,
         });
         self
     }

src/librustc_errors/emitter.rs

@@ -1339,7 +1339,7 @@ impl EmitterWriter {
         }
 
         let mut dst = self.dst.writable();
-        match write!(dst, "\n") {
+        match writeln!(dst) {
             Err(e) => panic!("failed to emit error: {}", e),
             _ => {
                 match dst.flush() {
@@ -1598,7 +1598,7 @@ fn emit_to_destination(rendered_buffer: &[Vec<StyledString>],
             dst.reset()?;
         }
         if !short_message && (!lvl.is_failure_note() || pos != rendered_buffer.len() - 1) {
-            write!(dst, "\n")?;
+            writeln!(dst)?;
         }
     }
     dst.flush()?;

src/librustc_target/spec/fuchsia_base.rs

@@ -19,7 +19,7 @@ pub fn opts() -> TargetOptions {
         is_like_fuchsia: true,
         linker_is_gnu: true,
         has_rpath: false,
-        pre_link_args: pre_link_args,
+        pre_link_args,
         pre_link_objects_exe: vec![
             "Scrt1.o".to_string()
         ],

src/libserialize/json.rs

@@ -461,7 +461,7 @@ impl<'a> Encoder<'a> {
     /// Creates a new JSON encoder whose output will be written to the writer
     /// specified.
     pub fn new(writer: &'a mut dyn fmt::Write) -> Encoder<'a> {
-        Encoder { writer: writer, is_emitting_map_key: false, }
+        Encoder { writer, is_emitting_map_key: false, }
     }
 }
 
@@ -513,7 +513,7 @@ impl<'a> crate::Encoder for Encoder<'a> {
         emit_enquoted_if_mapkey!(self, fmt_number_or_null(v))
     }
     fn emit_f32(&mut self, v: f32) -> EncodeResult {
-        self.emit_f64(v as f64)
+        self.emit_f64(f64::from(v))
     }
 
     fn emit_char(&mut self, v: char) -> EncodeResult {
@@ -763,7 +763,7 @@ impl<'a> crate::Encoder for PrettyEncoder<'a> {
         emit_enquoted_if_mapkey!(self, fmt_number_or_null(v))
     }
     fn emit_f32(&mut self, v: f32) -> EncodeResult {
-        self.emit_f64(v as f64)
+        self.emit_f64(f64::from(v))
     }
 
     fn emit_char(&mut self, v: char) -> EncodeResult {
@@ -1698,12 +1698,12 @@ impl<T: Iterator<Item=char>> Parser<T> {
                             if n2 < 0xDC00 || n2 > 0xDFFF {
                                 return self.error(LoneLeadingSurrogateInHexEscape)
                             }
-                            let c = (((n1 - 0xD800) as u32) << 10 |
-                                     (n2 - 0xDC00) as u32) + 0x1_0000;
+                            let c = (u32::from(n1 - 0xD800) << 10 |
+                                     u32::from(n2 - 0xDC00)) + 0x1_0000;
                             res.push(char::from_u32(c).unwrap());
                         }
 
-                        n => match char::from_u32(n as u32) {
+                        n => match char::from_u32(u32::from(n)) {
                             Some(c) => res.push(c),
                             None => return self.error(InvalidUnicodeCodePoint),
                         },
@@ -2405,7 +2405,7 @@ impl ToJson for Json {
 }
 
 impl ToJson for f32 {
-    fn to_json(&self) -> Json { (*self as f64).to_json() }
+    fn to_json(&self) -> Json { f64::from(*self).to_json() }
 }
 
 impl ToJson for f64 {

src/libserialize/leb128.rs

@@ -123,7 +123,7 @@ pub fn read_signed_leb128(data: &[u8], start_position: usize) -> (i128, usize) {
     loop {
         byte = data[position];
         position += 1;
-        result |= ((byte & 0x7F) as i128) << shift;
+        result |= i128::from(byte & 0x7F) << shift;
         shift += 7;
 
         if (byte & 0x80) == 0 {

src/libserialize/opaque.rs

@@ -296,13 +296,13 @@ impl<'a> serialize::Decoder for Decoder<'a> {
     #[inline]
     fn read_f64(&mut self) -> Result<f64, Self::Error> {
         let bits = self.read_u64()?;
-        Ok(unsafe { ::std::mem::transmute(bits) })
+        Ok(f64::from_bits(bits))
     }
 
     #[inline]
     fn read_f32(&mut self) -> Result<f32, Self::Error> {
         let bits = self.read_u32()?;
-        Ok(unsafe { ::std::mem::transmute(bits) })
+        Ok(f32::from_bits(bits))
     }
 
     #[inline]

src/libsyntax/ast.rs

@@ -1832,7 +1832,7 @@ impl Arg {
                         lt,
                         MutTy {
                             ty: infer_ty,
-                            mutbl: mutbl,
+                            mutbl,
                         },
                     ),
                     span,
@@ -2120,7 +2120,7 @@ impl PolyTraitRef {
         PolyTraitRef {
             bound_generic_params: generic_params,
             trait_ref: TraitRef {
-                path: path,
+                path,
                 ref_id: DUMMY_NODE_ID,
             },
             span,

src/libsyntax/ext/build.rs

@@ -815,7 +815,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
 
 
     fn pat(&self, span: Span, pat: PatKind) -> P<ast::Pat> {
-        P(ast::Pat { id: ast::DUMMY_NODE_ID, node: pat, span: span })
+        P(ast::Pat { id: ast::DUMMY_NODE_ID, node: pat, span })
     }
     fn pat_wild(&self, span: Span) -> P<ast::Pat> {
         self.pat(span, PatKind::Wild)

src/libsyntax/ext/expand.rs

@@ -231,7 +231,7 @@ pub struct MacroExpander<'a, 'b> {
 
 impl<'a, 'b> MacroExpander<'a, 'b> {
     pub fn new(cx: &'a mut ExtCtxt<'b>, monotonic: bool) -> Self {
-        MacroExpander { cx: cx, monotonic: monotonic }
+        MacroExpander { cx, monotonic }
     }
 
     pub fn expand_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
@@ -377,7 +377,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                             _ => item.clone(),
                         };
                         invocations.push(Invocation {
-                            kind: InvocationKind::Derive { path: path.clone(), item: item },
+                            kind: InvocationKind::Derive { path: path.clone(), item },
                             fragment_kind: invoc.fragment_kind,
                             expansion_data: ExpansionData {
                                 mark,
@@ -944,7 +944,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
     }
 
     fn collect_bang(&mut self, mac: ast::Mac, span: Span, kind: AstFragmentKind) -> AstFragment {
-        self.collect(kind, InvocationKind::Bang { mac: mac, ident: None, span: span })
+        self.collect(kind, InvocationKind::Bang { mac, ident: None, span })
     }
 
     fn collect_attr(&mut self,

src/libsyntax/ext/tt/quoted.rs

@@ -319,7 +319,7 @@ fn parse_tree(
         tokenstream::TokenTree::Delimited(span, delim, tts) => TokenTree::Delimited(
             span,
             Lrc::new(Delimited {
-                delim: delim,
+                delim,
                 tts: parse(
                     tts.into(),
                     expect_matchers,

src/libsyntax/ext/tt/transcribe.rs

@@ -23,8 +23,8 @@ enum Frame {
 impl Frame {
     /// Construct a new frame around the delimited set of tokens.
     fn new(tts: Vec<quoted::TokenTree>) -> Frame {
-        let forest = Lrc::new(quoted::Delimited { delim: token::NoDelim, tts: tts });
-        Frame::Delimited { forest: forest, idx: 0, span: DelimSpan::dummy() }
+        let forest = Lrc::new(quoted::Delimited { delim: token::NoDelim, tts });
+        Frame::Delimited { forest, idx: 0, span: DelimSpan::dummy() }
     }
 }
 
@@ -248,7 +248,7 @@ pub fn transcribe(
             // the previous results (from outside the Delimited).
             quoted::TokenTree::Delimited(mut span, delimited) => {
                 span = span.apply_mark(cx.current_expansion.mark);
-                stack.push(Frame::Delimited { forest: delimited, idx: 0, span: span });
+                stack.push(Frame::Delimited { forest: delimited, idx: 0, span });
                 result_stack.push(mem::replace(&mut result, Vec::new()));
             }
 

src/libsyntax/feature_gate.rs

@@ -1665,7 +1665,7 @@ impl<'a> Context<'a> {
 }
 
 pub fn check_attribute(attr: &ast::Attribute, parse_sess: &ParseSess, features: &Features) {
-    let cx = Context { features: features, parse_sess: parse_sess, plugin_attributes: &[] };
+    let cx = Context { features, parse_sess, plugin_attributes: &[] };
     cx.check_attribute(
         attr,
         attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name).map(|a| *a)),

src/libsyntax/parse/parser.rs

@@ -290,10 +290,10 @@ crate enum LastToken {
 }
 
 impl TokenCursorFrame {
-    fn new(sp: DelimSpan, delim: DelimToken, tts: &TokenStream) -> Self {
+    fn new(span: DelimSpan, delim: DelimToken, tts: &TokenStream) -> Self {
         TokenCursorFrame {
-            delim: delim,
-            span: sp,
+            delim,
+            span,
             open_delim: delim == token::NoDelim,
             tree_cursor: tts.clone().into_trees(),
             close_delim: delim == token::NoDelim,
@@ -1449,7 +1449,7 @@ impl<'a> Parser<'a> {
         let opt_lifetime = if self.check_lifetime() { Some(self.expect_lifetime()) } else { None };
         let mutbl = self.parse_mutability();
         let ty = self.parse_ty_no_plus()?;
-        return Ok(TyKind::Rptr(opt_lifetime, MutTy { ty: ty, mutbl: mutbl }));
+        return Ok(TyKind::Rptr(opt_lifetime, MutTy { ty, mutbl }));
     }
 
     fn parse_ptr(&mut self) -> PResult<'a, MutTy> {
@@ -1467,7 +1467,7 @@ impl<'a> Parser<'a> {
             Mutability::Immutable
         };
         let t = self.parse_ty_no_plus()?;
-        Ok(MutTy { ty: t, mutbl: mutbl })
+        Ok(MutTy { ty: t, mutbl })
     }
 
     fn is_named_argument(&self) -> bool {
@@ -4366,7 +4366,7 @@ impl<'a> Parser<'a> {
                     self.report_invalid_macro_expansion_item();
                 }
 
-                (ident, ast::MacroDef { tokens: tokens, legacy: true })
+                (ident, ast::MacroDef { tokens, legacy: true })
             }
             _ => return Ok(None),
         };
@@ -6789,12 +6789,12 @@ impl<'a> Parser<'a> {
         let hi = self.token.span;
         self.expect(&token::Semi)?;
         Ok(ast::ForeignItem {
-            ident: ident,
-            attrs: attrs,
+            ident,
+            attrs,
             node: ForeignItemKind::Ty,
             id: ast::DUMMY_NODE_ID,
             span: lo.to(hi),
-            vis: vis
+            vis
         })
     }
 

src/libsyntax/print/pp.rs

@@ -497,7 +497,7 @@ impl<'a> Printer<'a> {
 
     pub fn print_newline(&mut self, amount: isize) -> io::Result<()> {
         debug!("NEWLINE {}", amount);
-        let ret = write!(self.out, "\n");
+        let ret = writeln!(self.out);
         self.pending_indentation = 0;
         self.indent(amount);
         ret

src/libsyntax/source_map.rs

@@ -150,7 +150,7 @@ impl SourceMap {
                             -> SourceMap {
         SourceMap {
             files: Default::default(),
-            file_loader: file_loader,
+            file_loader,
             path_mapping,
         }
     }
@@ -396,7 +396,7 @@ impl SourceMap {
         let f = (*self.files.borrow().source_files)[idx].clone();
 
         match f.lookup_line(pos) {
-            Some(line) => Ok(SourceFileAndLine { sf: f, line: line }),
+            Some(line) => Ok(SourceFileAndLine { sf: f, line }),
             None => Err(f)
         }
     }
@@ -511,7 +511,7 @@ impl SourceMap {
                               start_col,
                               end_col: hi.col });
 
-        Ok(FileLines {file: lo.file, lines: lines})
+        Ok(FileLines {file: lo.file, lines})
     }
 
     /// Extracts the source surrounding the given `Span` using the `extract_source` function. The
@@ -820,7 +820,7 @@ impl SourceMap {
         let idx = self.lookup_source_file_idx(bpos);
         let sf = (*self.files.borrow().source_files)[idx].clone();
         let offset = bpos - sf.start_pos;
-        SourceFileAndBytePos {sf: sf, pos: offset}
+        SourceFileAndBytePos {sf, pos: offset}
     }
 
     /// Converts an absolute BytePos to a CharPos relative to the source_file.