make assoc_method return impl fmt::Display

Author: yotamofek

src/librustdoc/html/render/mod.rs

@@ -951,16 +951,15 @@ fn assoc_type(
     write_str(w, format_args!("{}", print_where_clause(generics, cx, indent, Ending::NoNewline)));
 }
 
-fn assoc_method(
-    w: &mut String,
-    meth: &clean::Item,
-    g: &clean::Generics,
-    d: &clean::FnDecl,
-    link: AssocItemLink<'_>,
+fn assoc_method<'a, 'tcx>(
+    meth: &'a clean::Item,
+    g: &'a clean::Generics,
+    d: &'a clean::FnDecl,
+    link: AssocItemLink<'a>,
     parent: ItemType,
-    cx: &Context<'_>,
+    cx: &'a Context<'tcx>,
     render_mode: RenderMode,
-) {
+) -> impl fmt::Display + 'a + Captures<'tcx> {
     let tcx = cx.tcx();
     let header = meth.fn_header(tcx).expect("Trying to get header from a non-function item");
     let name = meth.name.as_ref().unwrap();
@@ -976,54 +975,46 @@ fn assoc_method(
         ),
         RenderMode::ForDeref { .. } => "",
     };
-    let asyncness = header.asyncness.print_with_space();
-    let safety = header.safety.print_with_space();
-    let abi = print_abi_with_space(header.abi).to_string();
-    let href = assoc_href_attr(meth, link, cx).maybe_display();
-
-    // NOTE: `{:#}` does not print HTML formatting, `{}` does. So `g.print` can't be reused between the length calculation and `write!`.
-    let generics_len = format!("{:#}", g.print(cx)).len();
-    let mut header_len = "fn ".len()
-        + vis.len()
-        + defaultness.len()
-        + constness.len()
-        + asyncness.len()
-        + safety.len()
-        + abi.len()
-        + name.as_str().len()
-        + generics_len;
-
-    let notable_traits = notable_traits_button(&d.output, cx).maybe_display();
-
-    let (indent, indent_str, end_newline) = if parent == ItemType::Trait {
-        header_len += 4;
-        let indent_str = "    ";
-        write_str(w, format_args!("{}", render_attributes_in_pre(meth, indent_str, cx)));
-        (4, indent_str, Ending::NoNewline)
-    } else {
-        render_attributes_in_code(w, meth, cx);
-        (0, "", Ending::Newline)
-    };
-    w.reserve(header_len + "<a href=\"\" class=\"fn\">{".len() + "</a>".len());
-    write_str(
-        w,
-        format_args!(
+
+    fmt::from_fn(move |w| {
+        let asyncness = header.asyncness.print_with_space();
+        let safety = header.safety.print_with_space();
+        let abi = print_abi_with_space(header.abi).to_string();
+        let href = assoc_href_attr(meth, link, cx).maybe_display();
+
+        // NOTE: `{:#}` does not print HTML formatting, `{}` does. So `g.print` can't be reused between the length calculation and `write!`.
+        let generics_len = format!("{:#}", g.print(cx)).len();
+        let mut header_len = "fn ".len()
+            + vis.len()
+            + defaultness.len()
+            + constness.len()
+            + asyncness.len()
+            + safety.len()
+            + abi.len()
+            + name.as_str().len()
+            + generics_len;
+
+        let notable_traits = notable_traits_button(&d.output, cx).maybe_display();
+
+        let (indent, indent_str, end_newline) = if parent == ItemType::Trait {
+            header_len += 4;
+            let indent_str = "    ";
+            write!(w, "{}", render_attributes_in_pre(meth, indent_str, cx))?;
+            (4, indent_str, Ending::NoNewline)
+        } else {
+            render_attributes_in_code(w, meth, cx);
+            (0, "", Ending::Newline)
+        };
+        write!(
+            w,
             "{indent}{vis}{defaultness}{constness}{asyncness}{safety}{abi}fn \
-         <a{href} class=\"fn\">{name}</a>{generics}{decl}{notable_traits}{where_clause}",
+            <a{href} class=\"fn\">{name}</a>{generics}{decl}{notable_traits}{where_clause}",
             indent = indent_str,
-            vis = vis,
-            defaultness = defaultness,
-            constness = constness,
-            asyncness = asyncness,
-            safety = safety,
-            abi = abi,
-            href = href,
-            name = name,
             generics = g.print(cx),
             decl = d.full_print(header_len, indent, cx),
             where_clause = print_where_clause(g, cx, indent, end_newline),
-        ),
-    );
+        )
+    })
 }
 
 /// Writes a span containing the versions at which an item became stable and/or const-stable. For
@@ -1132,11 +1123,14 @@ fn render_assoc_item(
 ) {
     match &item.kind {
         clean::StrippedItem(..) => {}
-        clean::RequiredMethodItem(m) => {
-            assoc_method(w, item, &m.generics, &m.decl, link, parent, cx, render_mode)
-        }
-        clean::MethodItem(m, _) => {
-            assoc_method(w, item, &m.generics, &m.decl, link, parent, cx, render_mode)
+        clean::RequiredMethodItem(m) | clean::MethodItem(m, _) => {
+            write_str(
+                w,
+                format_args!(
+                    "{}",
+                    assoc_method(item, &m.generics, &m.decl, link, parent, cx, render_mode)
+                ),
+            );
         }
         clean::RequiredAssocConstItem(generics, ty) => assoc_const(
             w,