Put back "auto-collapse-implementors" setting

Author: GuillaumeGomez

src/librustdoc/html/render/mod.rs

@@ -451,6 +451,7 @@ fn settings(root_path: &str, suffix: &str, themes: &[StylePath]) -> Result<Strin
         ("auto-hide-method-docs", "Auto-hide item methods' documentation", false).into(),
         ("auto-hide-trait-implementations", "Auto-hide trait implementation documentation", false)
             .into(),
+        ("auto-collapse-implementors", "Auto-hide implementors of a trait", true).into(),
         ("go-to-only-result", "Directly go to item in search if there is only one result", false)
             .into(),
         ("line-numbers", "Show line numbers on code examples", false).into(),

src/librustdoc/html/static/js/main.js

@@ -789,6 +789,7 @@ function hideThemeButtonState() {
         }
 
         var hideMethodDocs = getSettingValue("auto-hide-method-docs") === "true";
+        var hideImplementors = getSettingValue("auto-collapse-implementors") !== "false";
         var hideImplementations = getSettingValue("auto-hide-trait-implementations") === "true";
         var hideLargeItemContents = getSettingValue("auto-hide-large-items") !== "false";
 
@@ -806,6 +807,10 @@ function hideThemeButtonState() {
             setImplementorsTogglesOpen("blanket-implementations-list", false);
         }
 
+        if (!hideImplementors) {
+            setImplementorsTogglesOpen("implementors-list", true);
+        }
+
         onEachLazy(document.getElementsByClassName("rustdoc-toggle"), function (e) {
             if (!hideLargeItemContents && hasClass(e, "type-contents-toggle")) {
                 e.open = true;