make render_struct return impl fmt::Display

Author: yotamofek

src/librustdoc/html/render/print_item.rs

@@ -1698,7 +1698,13 @@ fn render_enum_fields(
                         );
                     }
                     clean::VariantKind::Struct(ref s) => {
-                        render_struct(w, v, None, None, &s.fields, TAB, false, cx);
+                        write_str(
+                            w,
+                            format_args!(
+                                "{}",
+                                render_struct(v, None, None, &s.fields, TAB, false, cx)
+                            ),
+                        );
                     }
                 },
                 _ => unreachable!(),
@@ -1978,7 +1984,13 @@ fn item_constant(
 fn item_struct(w: &mut String, cx: &Context<'_>, it: &clean::Item, s: &clean::Struct) {
     wrap_item(w, |w| {
         render_attributes_in_code(w, it, cx);
-        render_struct(w, it, Some(&s.generics), s.ctor_kind, &s.fields, "", true, cx);
+        write_str(
+            w,
+            format_args!(
+                "{}",
+                render_struct(it, Some(&s.generics), s.ctor_kind, &s.fields, "", true, cx)
+            ),
+        );
     });
 
     write_str(w, format_args!("{}", document(cx, it, None, HeadingOffset::H2)));
@@ -2349,31 +2361,28 @@ fn render_union<'a, 'cx: 'a>(
     })
 }
 
-fn render_struct(
-    w: &mut String,
-    it: &clean::Item,
-    g: Option<&clean::Generics>,
+fn render_struct<'a, 'tcx>(
+    it: &'a clean::Item,
+    g: Option<&'a clean::Generics>,
     ty: Option<CtorKind>,
-    fields: &[clean::Item],
-    tab: &str,
+    fields: &'a [clean::Item],
+    tab: &'a str,
     structhead: bool,
-    cx: &Context<'_>,
-) {
-    write_str(
-        w,
-        format_args!(
+    cx: &'a Context<'tcx>,
+) -> impl fmt::Display + 'a + Captures<'tcx> {
+    fmt::from_fn(move |w| {
+        write!(
+            w,
             "{}{}{}",
             visibility_print_with_space(it, cx),
             if structhead { "struct " } else { "" },
             it.name.unwrap()
-        ),
-    );
-    if let Some(g) = g {
-        write_str(w, format_args!("{}", g.print(cx)));
-    }
-    write_str(
-        w,
-        format_args!(
+        )?;
+        if let Some(g) = g {
+            write!(w, "{}", g.print(cx))?;
+        }
+        write!(
+            w,
             "{}",
             render_struct_fields(
                 g,
@@ -2384,8 +2393,8 @@ fn render_struct(
                 it.has_stripped_entries().unwrap_or(false),
                 cx,
             )
-        ),
-    );
+        )
+    })
 }
 
 fn render_struct_fields<'a, 'tcx>(