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

Author: Centril

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 {