Rollup merge of rust-lang#138107 - yotamofek:pr/rustdoc/clippy, r=GuillaumeGomez

`librustdoc`: clippy fixes

First commit is all machine-generated fixes,
next two are some more lints fixed by hand/misc. cleanups

Inspired by the redundant `.and_then()` added in rust-lang#137320 , and [this comment](rust-lang#138090 (comment))

r? ```@GuillaumeGomez```

Author: matthiaskrgr

src/librustdoc/clean/mod.rs

@@ -2532,7 +2532,7 @@ fn clean_generic_args<'tcx>(
 ) -> GenericArgs {
     // FIXME(return_type_notation): Fix RTN parens rendering
     if let Some((inputs, output)) = generic_args.paren_sugar_inputs_output() {
-        let inputs = inputs.iter().map(|x| clean_ty(x, cx)).collect::<ThinVec<_>>().into();
+        let inputs = inputs.iter().map(|x| clean_ty(x, cx)).collect();
         let output = match output.kind {
             hir::TyKind::Tup(&[]) => None,
             _ => Some(Box::new(clean_ty(output, cx))),
@@ -2553,8 +2553,7 @@ fn clean_generic_args<'tcx>(
                 }
                 hir::GenericArg::Infer(_inf) => GenericArg::Infer,
             })
-            .collect::<ThinVec<_>>()
-            .into();
+            .collect();
         let constraints = generic_args
             .constraints
             .iter()

src/librustdoc/clean/types.rs

@@ -2417,7 +2417,7 @@ impl ConstantKind {
             ConstantKind::Local { body, .. } | ConstantKind::Anonymous { body } => {
                 rendered_const(tcx, tcx.hir_body(body), tcx.hir_body_owner_def_id(body))
             }
-            ConstantKind::Infer { .. } => "_".to_string(),
+            ConstantKind::Infer => "_".to_string(),
         }
     }
 

src/librustdoc/clean/utils.rs

@@ -223,7 +223,7 @@ fn clean_middle_generic_args_with_constraints<'tcx>(
 
     let args = clean_middle_generic_args(cx, args.map_bound(|args| &args[..]), has_self, did);
 
-    GenericArgs::AngleBracketed { args: args.into(), constraints }
+    GenericArgs::AngleBracketed { args, constraints }
 }
 
 pub(super) fn clean_middle_path<'tcx>(
@@ -394,7 +394,7 @@ pub(crate) fn print_evaluated_const(
 fn format_integer_with_underscore_sep(num: &str) -> String {
     let num_chars: Vec<_> = num.chars().collect();
     let mut num_start_index = if num_chars.first() == Some(&'-') { 1 } else { 0 };
-    let chunk_size = match num[num_start_index..].as_bytes() {
+    let chunk_size = match &num.as_bytes()[num_start_index..] {
         [b'0', b'b' | b'x', ..] => {
             num_start_index += 2;
             4
@@ -524,7 +524,7 @@ pub(crate) fn register_res(cx: &mut DocContext<'_>, res: Res) -> DefId {
             | AssocConst
             | Variant
             | Fn
-            | TyAlias { .. }
+            | TyAlias
             | Enum
             | Trait
             | Struct

src/librustdoc/display.rs

@@ -22,7 +22,7 @@ where
         let mut iter = self.into_iter();
         let Some(first) = iter.next() else { return Ok(()) };
         first.fmt(f)?;
-        while let Some(item) = iter.next() {
+        for item in iter {
             f.write_str(sep)?;
             item.fmt(f)?;
         }

src/librustdoc/doctest/extracted.rs

@@ -33,7 +33,7 @@ impl ExtractedDocTests {
         opts: &super::GlobalTestOptions,
         options: &RustdocOptions,
     ) {
-        let edition = scraped_test.edition(&options);
+        let edition = scraped_test.edition(options);
 
         let ScrapedDocTest { filename, line, langstr, text, name } = scraped_test;
 
@@ -48,7 +48,7 @@ impl ExtractedDocTests {
         let (full_test_code, size) = doctest.generate_unique_doctest(
             &text,
             langstr.test_harness,
-            &opts,
+            opts,
             Some(&opts.crate_name),
         );
         self.doctests.push(ExtractedDocTest {

src/librustdoc/html/format.rs

@@ -623,10 +623,9 @@ pub(crate) fn href_relative_parts<'fqp>(
         // e.g. linking to std::iter from std::vec (`dissimilar_part_count` will be 1)
         if f != r {
             let dissimilar_part_count = relative_to_fqp.len() - i;
-            let fqp_module = &fqp[i..fqp.len()];
+            let fqp_module = &fqp[i..];
             return Box::new(
-                iter::repeat(sym::dotdot)
-                    .take(dissimilar_part_count)
+                iter::repeat_n(sym::dotdot, dissimilar_part_count)
                     .chain(fqp_module.iter().copied()),
             );
         }
@@ -639,7 +638,7 @@ pub(crate) fn href_relative_parts<'fqp>(
         Ordering::Greater => {
             // e.g. linking to std::sync from std::sync::atomic
             let dissimilar_part_count = relative_to_fqp.len() - fqp.len();
-            Box::new(iter::repeat(sym::dotdot).take(dissimilar_part_count))
+            Box::new(iter::repeat_n(sym::dotdot, dissimilar_part_count))
         }
         Ordering::Equal => {
             // linking to the same module
@@ -770,10 +769,9 @@ fn primitive_link_fragment(
                     ExternalLocation::Local => {
                         let cname_sym = ExternalCrate { crate_num: def_id.krate }.name(cx.tcx());
                         Some(if cx.current.first() == Some(&cname_sym) {
-                            iter::repeat(sym::dotdot).take(cx.current.len() - 1).collect()
+                            iter::repeat_n(sym::dotdot, cx.current.len() - 1).collect()
                         } else {
-                            iter::repeat(sym::dotdot)
-                                .take(cx.current.len())
+                            iter::repeat_n(sym::dotdot, cx.current.len())
                                 .chain(iter::once(cname_sym))
                                 .collect()
                         })

src/librustdoc/html/highlight.rs

@@ -100,7 +100,7 @@ fn write_header(
     }
 
     if let Some(extra) = extra_content {
-        out.push_str(&extra);
+        out.push_str(extra);
     }
     if class.is_empty() {
         write_str(
@@ -131,7 +131,7 @@ fn write_header(
 /// * If the other `Class` is unclassified and only contains white characters (backline,
 ///   whitespace, etc), it can be merged.
 /// * `Class::Ident` is considered the same as unclassified (because it doesn't have an associated
-///    CSS class).
+///   CSS class).
 fn can_merge(class1: Option<Class>, class2: Option<Class>, text: &str) -> bool {
     match (class1, class2) {
         (Some(c1), Some(c2)) => c1.is_equal_to(c2),
@@ -233,7 +233,7 @@ impl<F: Write> TokenHandler<'_, '_, F> {
 
     #[inline]
     fn write_line_number(&mut self, line: u32, extra: &'static str) {
-        (self.write_line_number)(&mut self.out, line, extra);
+        (self.write_line_number)(self.out, line, extra);
     }
 }
 
@@ -610,7 +610,7 @@ impl Decorations {
         let (mut starts, mut ends): (Vec<_>, Vec<_>) = info
             .0
             .iter()
-            .flat_map(|(&kind, ranges)| ranges.into_iter().map(move |&(lo, hi)| ((lo, kind), hi)))
+            .flat_map(|(&kind, ranges)| ranges.iter().map(move |&(lo, hi)| ((lo, kind), hi)))
             .unzip();
 
         // Sort the sequences in document order.

src/librustdoc/html/markdown.rs

@@ -1791,7 +1791,7 @@ pub(crate) fn markdown_links<'md, R>(
                     }
                 }
             } else if !c.is_ascii_whitespace() {
-                while let Some((j, c)) = iter.next() {
+                for (j, c) in iter.by_ref() {
                     if c.is_ascii_whitespace() {
                         return MarkdownLinkRange::Destination(i + span.start..j + span.start);
                     }

src/librustdoc/html/render/print_item.rs

@@ -1,6 +1,6 @@
 use std::cmp::Ordering;
-use std::fmt;
-use std::fmt::{Display, Write as _};
+use std::fmt::{self, Display, Write as _};
+use std::iter;
 
 use rinja::Template;
 use rustc_abi::VariantIdx;
@@ -1192,10 +1192,8 @@ fn item_trait(cx: &Context<'_>, it: &clean::Item, t: &clean::Trait) -> impl fmt:
         // to already be in the HTML, and will be ignored.
         //
         // [JSONP]: https://en.wikipedia.org/wiki/JSONP
-        let mut js_src_path: UrlPartsBuilder = std::iter::repeat("..")
-            .take(cx.current.len())
-            .chain(std::iter::once("trait.impl"))
-            .collect();
+        let mut js_src_path: UrlPartsBuilder =
+            iter::repeat_n("..", cx.current.len()).chain(iter::once("trait.impl")).collect();
         if let Some(did) = it.item_id.as_def_id()
             && let get_extern = { || cx.shared.cache.external_paths.get(&did).map(|s| &s.0) }
             && let Some(fqp) = cx.shared.cache.exact_paths.get(&did).or_else(get_extern)
@@ -1446,10 +1444,8 @@ fn item_type_alias(cx: &Context<'_>, it: &clean::Item, t: &clean::TypeAlias) ->
             && let get_local = { || cache.paths.get(&self_did).map(|(p, _)| p) }
             && let Some(self_fqp) = cache.exact_paths.get(&self_did).or_else(get_local)
         {
-            let mut js_src_path: UrlPartsBuilder = std::iter::repeat("..")
-                .take(cx.current.len())
-                .chain(std::iter::once("type.impl"))
-                .collect();
+            let mut js_src_path: UrlPartsBuilder =
+                iter::repeat_n("..", cx.current.len()).chain(iter::once("type.impl")).collect();
             js_src_path.extend(target_fqp[..target_fqp.len() - 1].iter().copied());
             js_src_path.push_fmt(format_args!("{target_type}.{}.js", target_fqp.last().unwrap()));
             let self_path = fmt::from_fn(|f| self_fqp.iter().joined("::", f));
@@ -1493,7 +1489,7 @@ fn item_union(cx: &Context<'_>, it: &clean::Item, s: &clean::Union) -> impl fmt:
 
         fn fields_iter(
             &self,
-        ) -> std::iter::Peekable<impl Iterator<Item = (&'a clean::Item, &'a clean::Type)>> {
+        ) -> iter::Peekable<impl Iterator<Item = (&'a clean::Item, &'a clean::Type)>> {
             self.s
                 .fields
                 .iter()

src/librustdoc/html/render/search_index.rs

@@ -842,10 +842,7 @@ pub(crate) fn get_function_type_for_search(
         }
         clean::ConstantItem(ref c) => make_nullary_fn(&c.type_),
         clean::StaticItem(ref s) => make_nullary_fn(&s.type_),
-        clean::StructFieldItem(ref t) => {
-            let Some(parent) = parent else {
-                return None;
-            };
+        clean::StructFieldItem(ref t) if let Some(parent) = parent => {
             let mut rgen: FxIndexMap<SimplifiedParam, (isize, Vec<RenderType>)> =
                 Default::default();
             let output = get_index_type(t, vec![], &mut rgen);