rustdoc: Add setting for hiding large items

src/librustdoc/html/render/mod.rs

@@ -486,6 +486,7 @@ fn settings(root_path: &str, suffix: &str, themes: &[StylePath]) -> Result<Strin
             ],
         )
             .into(),
+        ("auto-hide-large-items", "Auto-hide item contents for large items.", true).into(),
         ("auto-hide-attributes", "Auto-hide item attributes.", true).into(),
         ("auto-hide-method-docs", "Auto-hide item methods' documentation", false).into(),
         ("auto-hide-trait-implementations", "Auto-hide trait implementation documentation", true)

src/librustdoc/html/static/main.js

@@ -2705,8 +2705,12 @@ function hideThemeButtonState() {
                 }
             } else if (hasClass(e, "type-contents-toggle")) {
                 let text = e.getAttribute("data-toggle-text");
-                let tog = createToggle(toggle, `Show ${text}`, null, "", true);
+                let hideItemContents = getSettingValue("auto-hide-large-items") !== "false";
+                let tog = createToggle(toggle, `Show ${text}`, null, "", !hideItemContents);
                 e.parentNode.insertBefore(tog,  e);
+                if (hideItemContents) {
+                    collapseDocs(e.previousSibling.childNodes[0], "toggle");
+                }
             }
             if (e.parentNode.id === "main") {
                 var otherMessage = "";