Get rid of unnecessary BufDisplay abstraction

src/librustdoc/html/layout.rs

@@ -1,4 +1,4 @@
-use std::fmt::{self, Display};
+use std::fmt::Display;
 use std::path::PathBuf;
 
 use askama::Template;
@@ -71,23 +71,6 @@ struct PageLayout<'a> {
 
 pub(crate) use crate::html::render::sidebar::filters;
 
-/// Implements [`Display`] for a function that accepts a mutable reference to a [`String`], and (optionally) writes to it.
-///
-/// The wrapped function will receive an empty string, and can modify it,
-/// and the `Display` implementation will write the contents of the string after the function has finished.
-pub(crate) struct BufDisplay<F>(pub F);
-
-impl<F> Display for BufDisplay<F>
-where
-    F: Fn(&mut String),
-{
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let mut buf = String::new();
-        self.0(&mut buf);
-        f.write_str(&buf)
-    }
-}
-
 pub(crate) fn render<T: Display, S: Display>(
     layout: &Layout,
     page: &Page<'_>,

src/librustdoc/html/render/context.rs

@@ -28,11 +28,10 @@ use crate::formats::cache::Cache;
 use crate::formats::item_type::ItemType;
 use crate::html::escape::Escape;
 use crate::html::format::join_with_double_colon;
-use crate::html::layout::{self, BufDisplay};
 use crate::html::markdown::{self, ErrorCodes, IdMap, plain_text_summary};
 use crate::html::render::write_shared::write_shared;
 use crate::html::url_parts_builder::UrlPartsBuilder;
-use crate::html::{sources, static_files};
+use crate::html::{layout, sources, static_files};
 use crate::scrape_examples::AllCallLocations;
 use crate::{DOC_RUST_LANG_ORG_VERSION, try_err};
 
@@ -250,9 +249,7 @@ impl<'tcx> Context<'tcx> {
             layout::render(
                 &self.shared.layout,
                 &page,
-                BufDisplay(|buf: &mut String| {
-                    print_sidebar(self, it, buf);
-                }),
+                fmt::from_fn(|f| print_sidebar(self, it, f)),
                 content,
                 &self.shared.style_files,
             )

src/librustdoc/html/render/mod.rs

@@ -538,7 +538,7 @@ fn document(
     }
 
     fmt::from_fn(move |f| {
-        document_item_info(cx, item, parent).render_into(f).unwrap();
+        document_item_info(cx, item, parent).render_into(f)?;
         if parent.is_none() {
             write!(f, "{}", document_full_collapsible(item, cx, heading_offset))
         } else {
@@ -582,7 +582,7 @@ fn document_short(
     show_def_docs: bool,
 ) -> impl fmt::Display {
     fmt::from_fn(move |f| {
-        document_item_info(cx, item, Some(parent)).render_into(f).unwrap();
+        document_item_info(cx, item, Some(parent)).render_into(f)?;
         if !show_def_docs {
             return Ok(());
         }
@@ -661,7 +661,7 @@ fn document_full_inner(
         };
 
         if let clean::ItemKind::FunctionItem(..) | clean::ItemKind::MethodItem(..) = kind {
-            render_call_locations(f, cx, item);
+            render_call_locations(f, cx, item)?;
         }
         Ok(())
     })
@@ -2584,11 +2584,15 @@ const MAX_FULL_EXAMPLES: usize = 5;
 const NUM_VISIBLE_LINES: usize = 10;
 
 /// Generates the HTML for example call locations generated via the --scrape-examples flag.
-fn render_call_locations<W: fmt::Write>(mut w: W, cx: &Context<'_>, item: &clean::Item) {
+fn render_call_locations<W: fmt::Write>(
+    mut w: W,
+    cx: &Context<'_>,
+    item: &clean::Item,
+) -> fmt::Result {
     let tcx = cx.tcx();
     let def_id = item.item_id.expect_def_id();
     let key = tcx.def_path_hash(def_id);
-    let Some(call_locations) = cx.shared.call_locations.get(&key) else { return };
+    let Some(call_locations) = cx.shared.call_locations.get(&key) else { return Ok(()) };
 
     // Generate a unique ID so users can link to this section for a given method
     let id = cx.derive_id("scraped-examples");
@@ -2602,8 +2606,7 @@ fn render_call_locations<W: fmt::Write>(mut w: W, cx: &Context<'_>, item: &clean
           </h5>",
         root_path = cx.root_path(),
         id = id
-    )
-    .unwrap();
+    )?;
 
     // Create a URL to a particular location in a reverse-dependency's source file
     let link_to_loc = |call_data: &CallData, loc: &CallLocation| -> (String, String) {
@@ -2705,7 +2708,8 @@ fn render_call_locations<W: fmt::Write>(mut w: W, cx: &Context<'_>, item: &clean
                 title: init_title,
                 locations: locations_encoded,
             }),
-        );
+        )
+        .unwrap();
 
         true
     };
@@ -2761,8 +2765,7 @@ fn render_call_locations<W: fmt::Write>(mut w: W, cx: &Context<'_>, item: &clean
                   <div class=\"hide-more\">Hide additional examples</div>\
                   <div class=\"more-scraped-examples\">\
                     <div class=\"toggle-line\"><div class=\"toggle-line-inner\"></div></div>"
-        )
-        .unwrap();
+        )?;
 
         // Only generate inline code for MAX_FULL_EXAMPLES number of examples. Otherwise we could
         // make the page arbitrarily huge!
@@ -2774,23 +2777,21 @@ fn render_call_locations<W: fmt::Write>(mut w: W, cx: &Context<'_>, item: &clean
         if it.peek().is_some() {
             w.write_str(
                 r#"<div class="example-links">Additional examples can be found in:<br><ul>"#,
-            )
-            .unwrap();
-            it.for_each(|(_, call_data)| {
+            )?;
+            it.try_for_each(|(_, call_data)| {
                 let (url, _) = link_to_loc(call_data, &call_data.locations[0]);
                 write!(
                     w,
                     r#"<li><a href="{url}">{name}</a></li>"#,
                     url = url,
                     name = call_data.display_name
                 )
-                .unwrap();
-            });
-            w.write_str("</ul></div>").unwrap();
+            })?;
+            w.write_str("</ul></div>")?;
         }
 
-        w.write_str("</div></details>").unwrap();
+        w.write_str("</div></details>")?;
     }
 
-    w.write_str("</div>").unwrap();
+    w.write_str("</div>")
 }

src/librustdoc/html/render/sidebar.rs

@@ -1,5 +1,6 @@
 use std::borrow::Cow;
 use std::cmp::Ordering;
+use std::fmt;
 
 use askama::Template;
 use rustc_data_structures::fx::FxHashSet;
@@ -135,7 +136,11 @@ pub(crate) mod filters {
     }
 }
 
-pub(super) fn print_sidebar(cx: &Context<'_>, it: &clean::Item, buffer: &mut String) {
+pub(super) fn print_sidebar(
+    cx: &Context<'_>,
+    it: &clean::Item,
+    mut buffer: impl fmt::Write,
+) -> fmt::Result {
     let mut ids = IdMap::new();
     let mut blocks: Vec<LinkBlock<'_>> = docblock_toc(cx, it, &mut ids).into_iter().collect();
     let deref_id_map = cx.deref_id_map.borrow();
@@ -195,7 +200,8 @@ pub(super) fn print_sidebar(cx: &Context<'_>, it: &clean::Item, buffer: &mut Str
         blocks,
         path,
     };
-    sidebar.render_into(buffer).unwrap();
+    sidebar.render_into(&mut buffer)?;
+    Ok(())
 }
 
 fn get_struct_fields_name<'a>(fields: &'a [clean::Item]) -> Vec<Link<'a>> {

src/librustdoc/html/sources.rs

@@ -11,9 +11,8 @@ use rustc_session::Session;
 use rustc_span::{FileName, FileNameDisplayPreference, RealFileName, sym};
 use tracing::info;
 
-use super::highlight;
-use super::layout::{self, BufDisplay};
 use super::render::Context;
+use super::{highlight, layout};
 use crate::clean;
 use crate::clean::utils::has_doc_flag;
 use crate::docfs::PathError;
@@ -243,16 +242,16 @@ impl SourceCollector<'_, '_> {
             &shared.layout,
             &page,
             "",
-            BufDisplay(|buf: &mut String| {
+            fmt::from_fn(|f| {
                 print_src(
-                    buf,
+                    f,
                     contents,
                     file_span,
                     self.cx,
                     &root_path,
                     &highlight::DecorationInfo::default(),
                     &source_context,
-                );
+                )
             }),
             &shared.style_files,
         );
@@ -331,7 +330,7 @@ pub(crate) fn print_src(
     root_path: &str,
     decoration_info: &highlight::DecorationInfo,
     source_context: &SourceContext<'_>,
-) {
+) -> fmt::Result {
     let mut lines = s.lines().count();
     let line_info = if let SourceContext::Embedded(info) = source_context {
         highlight::LineInfo::new_scraped(lines as u32, info.offset as u32)
@@ -367,12 +366,10 @@ pub(crate) fn print_src(
             },
             max_nb_digits,
         }
-        .render_into(&mut writer)
-        .unwrap(),
+        .render_into(&mut writer),
         SourceContext::Embedded(info) => {
-            ScrapedSource { info, code_html: code, max_nb_digits }
-                .render_into(&mut writer)
-                .unwrap();
+            ScrapedSource { info, code_html: code, max_nb_digits }.render_into(&mut writer)
         }
-    };
+    }?;
+    Ok(())
 }