Add support for "always theme" in setting

src/librustdoc/html/render/mod.rs

@@ -421,6 +421,12 @@ fn settings(root_path: &str, suffix: &str, theme_names: Vec<String>) -> Result<S
             "Theme preferences",
             vec![
                 Setting::from(("use-system-theme", "Use system theme", true)),
+                Setting::Select {
+                    js_data_name: "theme",
+                    description: "Theme",
+                    default_value: "light",
+                    options: theme_names.clone(),
+                },
                 Setting::Select {
                     js_data_name: "preferred-dark-theme",
                     description: "Preferred dark theme",

src/librustdoc/html/static/js/settings.js

@@ -1,15 +1,18 @@
 // Local js definitions:
 /* global getSettingValue, getVirtualKey, onEachLazy, updateLocalStorage, updateSystemTheme */
+/* global addClass, removeClass */
 
 (function () {
     function changeSetting(settingName, value) {
         updateLocalStorage("rustdoc-" + settingName, value);
 
         switch (settingName) {
+            case "theme":
             case "preferred-dark-theme":
             case "preferred-light-theme":
             case "use-system-theme":
                 updateSystemTheme();
+                updateLightAndDark();
                 break;
         }
     }
@@ -29,7 +32,32 @@
         }
     }
 
+    function showLightAndDark() {
+        addClass(document.getElementById("theme").parentElement.parentElement, "hidden");
+        removeClass(document.getElementById("preferred-light-theme").parentElement.parentElement,
+            "hidden");
+        removeClass(document.getElementById("preferred-dark-theme").parentElement.parentElement,
+            "hidden");
+    }
+
+    function hideLightAndDark() {
+        addClass(document.getElementById("preferred-light-theme").parentElement.parentElement,
+            "hidden");
+        addClass(document.getElementById("preferred-dark-theme").parentElement.parentElement,
+            "hidden");
+        removeClass(document.getElementById("theme").parentElement.parentElement, "hidden");
+    }
+
+    function updateLightAndDark() {
+        if (getSettingValue("use-system-theme") !== "false") {
+            showLightAndDark();
+        } else {
+            hideLightAndDark();
+        }
+    }
+
     function setEvents() {
+        updateLightAndDark();
         onEachLazy(document.getElementsByClassName("slider"), function(elem) {
             var toggle = elem.previousElementSibling;
             var settingId = toggle.id;

src/librustdoc/html/static/js/storage.js

@@ -187,22 +187,25 @@ var updateSystemTheme = (function() {
     var mql = window.matchMedia("(prefers-color-scheme: dark)");
 
     function handlePreferenceChange(mql) {
+        let use = function(theme) {
+            switchTheme(window.currentTheme, window.mainTheme, theme, true);
+        };
         // maybe the user has disabled the setting in the meantime!
         if (getSettingValue("use-system-theme") !== "false") {
             var lightTheme = getSettingValue("preferred-light-theme") || "light";
             var darkTheme = getSettingValue("preferred-dark-theme") || "dark";
 
             if (mql.matches) {
-                // prefers a dark theme
+                use(darkTheme);
-                switchTheme(window.currentTheme, window.mainTheme, darkTheme, true);
             } else {
                 // prefers a light theme, or has no preference
-                switchTheme(window.currentTheme, window.mainTheme, lightTheme, true);
+                use(lightTheme);
             }
-
             // note: we save the theme so that it doesn't suddenly change when
             // the user disables "use-system-theme" and reloads the page or
             // navigates to another page
+        } else {
+            use(getSettingValue("theme"));
         }
     }
 

src/test/rustdoc-gui/toggle-docs-mobile.goml

@@ -1,12 +1,12 @@
 goto: file://|DOC_PATH|/test_docs/struct.Foo.html
 size: (433, 600)
 assert-attribute: (".top-doc", {"open": ""})
-click: (4, 240) // This is the position of the top doc comment toggle
+click: (4, 260) // This is the position of the top doc comment toggle
 assert-attribute-false: (".top-doc", {"open": ""})
-click: (4, 240)
+click: (4, 260)
 assert-attribute: (".top-doc", {"open": ""})
 // To ensure that the toggle isn't over the text, we check that the toggle isn't clicked.
-click: (3, 240)
+click: (3, 260)
 assert-attribute: (".top-doc", {"open": ""})
 
 // Assert the position of the toggle on the top doc block.
@@ -22,10 +22,10 @@ assert-position: (
 // Now we do the same but with a little bigger width
 size: (600, 600)
 assert-attribute: (".top-doc", {"open": ""})
-click: (4, 240) // New Y position since all search elements are back on one line.
+click: (4, 260) // New Y position since all search elements are back on one line.
 assert-attribute-false: (".top-doc", {"open": ""})
-click: (4, 240)
+click: (4, 260)
 assert-attribute: (".top-doc", {"open": ""})
 // To ensure that the toggle isn't over the text, we check that the toggle isn't clicked.
-click: (3, 240)
+click: (3, 260)
 assert-attribute: (".top-doc", {"open": ""})