Rollup merge of #105050 - WaffleLapkin:uselessrefign, r=jyn514

Remove useless borrows and derefs

They are nothing more than noise.
<sub>These are not all of them, but my clippy started crashing (stack overflow), so rip :(</sub>

compiler/rustc_ast/src/ast.rs

@@ -1179,7 +1179,7 @@ impl Expr {
     pub fn peel_parens(&self) -> &Expr {
         let mut expr = self;
         while let ExprKind::Paren(inner) = &expr.kind {
-            expr = &inner;
+            expr = inner;
         }
         expr
     }
@@ -2029,7 +2029,7 @@ impl Ty {
     pub fn peel_refs(&self) -> &Self {
         let mut final_ty = self;
         while let TyKind::Rptr(_, MutTy { ty, .. }) = &final_ty.kind {
-            final_ty = &ty;
+            final_ty = ty;
         }
         final_ty
     }

compiler/rustc_ast/src/mut_visit.rs

@@ -736,8 +736,7 @@ pub fn visit_token<T: MutVisitor>(t: &mut Token, vis: &mut T) {
             return; // Avoid visiting the span for the second time.
         }
         token::Interpolated(nt) => {
-            let mut nt = Lrc::make_mut(nt);
-            visit_nonterminal(&mut nt, vis);
+            visit_nonterminal(Lrc::make_mut(nt), vis);
         }
         _ => {}
     }

compiler/rustc_ast/src/tokenstream.rs

@@ -64,7 +64,7 @@ impl TokenTree {
         match (self, other) {
             (TokenTree::Token(token, _), TokenTree::Token(token2, _)) => token.kind == token2.kind,
             (TokenTree::Delimited(_, delim, tts), TokenTree::Delimited(_, delim2, tts2)) => {
-                delim == delim2 && tts.eq_unspanned(&tts2)
+                delim == delim2 && tts.eq_unspanned(tts2)
             }
             _ => false,
         }
@@ -402,7 +402,7 @@ impl TokenStream {
         let mut t1 = self.trees();
         let mut t2 = other.trees();
         for (t1, t2) in iter::zip(&mut t1, &mut t2) {
-            if !t1.eq_unspanned(&t2) {
+            if !t1.eq_unspanned(t2) {
                 return false;
             }
         }
@@ -475,7 +475,7 @@ impl TokenStream {
             token::Interpolated(nt) => TokenTree::Delimited(
                 DelimSpan::from_single(token.span),
                 Delimiter::Invisible,
-                TokenStream::from_nonterminal_ast(&nt).flattened(),
+                TokenStream::from_nonterminal_ast(nt).flattened(),
             ),
             _ => TokenTree::Token(token.clone(), spacing),
         }
@@ -511,7 +511,7 @@ impl TokenStream {
     fn try_glue_to_last(vec: &mut Vec<TokenTree>, tt: &TokenTree) -> bool {
         if let Some(TokenTree::Token(last_tok, Spacing::Joint)) = vec.last()
             && let TokenTree::Token(tok, spacing) = tt
-            && let Some(glued_tok) = last_tok.glue(&tok)
+            && let Some(glued_tok) = last_tok.glue(tok)
         {
             // ...then overwrite the last token tree in `vec` with the
             // glued token, and skip the first token tree from `stream`.

compiler/rustc_ast/src/util/comments.rs

@@ -110,7 +110,7 @@ pub fn beautify_doc_string(data: Symbol, kind: CommentKind) -> Symbol {
         } else {
             &mut lines
         };
-        if let Some(horizontal) = get_horizontal_trim(&lines, kind) {
+        if let Some(horizontal) = get_horizontal_trim(lines, kind) {
             changes = true;
             // remove a "[ \t]*\*" block from each line, if possible
             for line in lines.iter_mut() {
@@ -147,7 +147,7 @@ fn all_whitespace(s: &str, col: CharPos) -> Option<usize> {
 
 fn trim_whitespace_prefix(s: &str, col: CharPos) -> &str {
     let len = s.len();
-    match all_whitespace(&s, col) {
+    match all_whitespace(s, col) {
         Some(col) => {
             if col < len {
                 &s[col..]

compiler/rustc_ast/src/util/literal.rs

@@ -52,14 +52,14 @@ impl LitKind {
                 // new symbol because the string in the LitKind is different to the
                 // string in the token.
                 let s = symbol.as_str();
-                let symbol = if s.contains(&['\\', '\r']) {
+                let symbol = if s.contains(['\\', '\r']) {
                     let mut buf = String::with_capacity(s.len());
                     let mut error = Ok(());
                     // Force-inlining here is aggressive but the closure is
                     // called on every char in the string, so it can be
                     // hot in programs with many long strings.
                     unescape_literal(
-                        &s,
+                        s,
                         Mode::Str,
                         &mut #[inline(always)]
                         |_, unescaped_char| match unescaped_char {
@@ -85,7 +85,7 @@ impl LitKind {
                     if s.contains('\r') {
                         let mut buf = String::with_capacity(s.len());
                         let mut error = Ok(());
-                        unescape_literal(&s, Mode::RawStr, &mut |_, unescaped_char| {
+                        unescape_literal(s, Mode::RawStr, &mut |_, unescaped_char| {
                             match unescaped_char {
                                 Ok(c) => buf.push(c),
                                 Err(err) => {
@@ -106,7 +106,7 @@ impl LitKind {
                 let s = symbol.as_str();
                 let mut buf = Vec::with_capacity(s.len());
                 let mut error = Ok(());
-                unescape_literal(&s, Mode::ByteStr, &mut |_, c| match c {
+                unescape_literal(s, Mode::ByteStr, &mut |_, c| match c {
                     Ok(c) => buf.push(byte_from_char(c)),
                     Err(err) => {
                         if err.is_fatal() {
@@ -122,7 +122,7 @@ impl LitKind {
                 let bytes = if s.contains('\r') {
                     let mut buf = Vec::with_capacity(s.len());
                     let mut error = Ok(());
-                    unescape_literal(&s, Mode::RawByteStr, &mut |_, c| match c {
+                    unescape_literal(s, Mode::RawByteStr, &mut |_, c| match c {
                         Ok(c) => buf.push(byte_from_char(c)),
                         Err(err) => {
                             if err.is_fatal() {

compiler/rustc_ast/src/util/parser.rs

@@ -384,7 +384,7 @@ pub fn contains_exterior_struct_lit(value: &ast::Expr) -> bool {
         | ast::ExprKind::AssignOp(_, lhs, rhs)
         | ast::ExprKind::Binary(_, lhs, rhs) => {
             // X { y: 1 } + X { y: 2 }
-            contains_exterior_struct_lit(&lhs) || contains_exterior_struct_lit(&rhs)
+            contains_exterior_struct_lit(lhs) || contains_exterior_struct_lit(rhs)
         }
         ast::ExprKind::Await(x)
         | ast::ExprKind::Unary(_, x)
@@ -393,12 +393,12 @@ pub fn contains_exterior_struct_lit(value: &ast::Expr) -> bool {
         | ast::ExprKind::Field(x, _)
         | ast::ExprKind::Index(x, _) => {
             // &X { y: 1 }, X { y: 1 }.y
-            contains_exterior_struct_lit(&x)
+            contains_exterior_struct_lit(x)
         }
 
         ast::ExprKind::MethodCall(box ast::MethodCall { receiver, .. }) => {
             // X { y: 1 }.bar(...)
-            contains_exterior_struct_lit(&receiver)
+            contains_exterior_struct_lit(receiver)
         }
 
         _ => false,

compiler/rustc_ast/src/util/unicode.rs

@@ -17,7 +17,7 @@ pub fn contains_text_flow_control_chars(s: &str) -> bool {
     // U+2069 - E2 81 A9
     let mut bytes = s.as_bytes();
     loop {
-        match core::slice::memchr::memchr(0xE2, &bytes) {
+        match core::slice::memchr::memchr(0xE2, bytes) {
             Some(idx) => {
                 // bytes are valid UTF-8 -> E2 must be followed by two bytes
                 let ch = &bytes[idx..idx + 3];