Rollup merge of #83721 - GuillaumeGomez:copy-use, r=Nemo157

Add a button to copy the "use statement"

Fixes https://github.com/rust-lang/rust/issues/50239

When clicking on the button, it'll add the elements prepended by "use " and will end with a ";". So in the images below, I now have in my clipboard `use std::fs::OpenOptions;`.

A screenshot of the newly added button:

![Screenshot from 2021-03-31 22-12-12](https://user-images.githubusercontent.com/3050060/113205430-90e64500-926e-11eb-8538-529829f611ec.png)

A screenshot after it was clicked:

![Screenshot from 2021-03-31 22-15-31](https://user-images.githubusercontent.com/3050060/113205532-ad827d00-926e-11eb-893d-35f2f8f92696.png)

r? `@Nemo157`

6 files changed, 55 insertions, 13 deletions

diff --git a/src/librustdoc/html/static/main.js b/src/librustdoc/html/static/main.js
index da2952bbebd..f2e62ee7b6b 100644
--- a/src/librustdoc/html/static/main.js
+++ b/src/librustdoc/html/static/main.js
@@ -3061,3 +3061,28 @@ function hideThemeButtonState() {
     window.onhashchange = onHashChange;
     setupSearchLoader();
 }());
+
+function copy_path(but) {
+    var parent = but.parentElement;
+    var path = [];
+
+    onEach(parent.childNodes, function(child) {
+        if (child.tagName === 'A') {
+            path.push(child.textContent);
+        }
+    });
+
+    var el = document.createElement('textarea');
+    el.value = 'use ' + path.join('::') + ';';
+    el.setAttribute('readonly', '');
+    // To not make it appear on the screen.
+    el.style.position = 'absolute';
+    el.style.left = '-9999px';
+
+    document.body.appendChild(el);
+    el.select();
+    document.execCommand('copy');
+    document.body.removeChild(el);
+
+    but.textContent = '✓';
+}
diff --git a/src/librustdoc/html/static/noscript.css b/src/librustdoc/html/static/noscript.css
index c9fed989ec0..4d3332877c0 100644
--- a/src/librustdoc/html/static/noscript.css
+++ b/src/librustdoc/html/static/noscript.css
@@ -33,3 +33,8 @@ rules.
 	/* Since there is no toggle (the "[-]") when JS is disabled, no need for this margin either. */
 	margin-left: 0 !important;
 }
+
+#copy-path {
+	/* It requires JS to work so no need to display it in this case. */
+	display: none;
+}
diff --git a/src/librustdoc/html/static/rustdoc.css b/src/librustdoc/html/static/rustdoc.css
index f5a034a0d24..07dfb7f5cf0 100644
--- a/src/librustdoc/html/static/rustdoc.css
+++ b/src/librustdoc/html/static/rustdoc.css
@@ -1318,20 +1318,29 @@ h4 > .notable-traits {
 	outline: none;
 }
 
+#theme-picker, #settings-menu, .help-button, #copy-path {
+	padding: 4px;
+	width: 27px;
+	height: 29px;
+	border: 1px solid;
+	border-radius: 3px;
+	cursor: pointer;
+}
+
 .help-button {
 	right: 30px;
 	font-family: "Fira Sans", Arial, sans-serif;
 	text-align: center;
 	font-size: 17px;
+	padding-top: 2px;
 }
 
-#theme-picker, #settings-menu, .help-button {
-	padding: 4px;
-	width: 27px;
-	height: 29px;
-	border: 1px solid;
-	border-radius: 3px;
-	cursor: pointer;
+#copy-path {
+	height: 30px;
+	font-size: 18px;
+	margin-left: 10px;
+	padding: 0 6px;
+	width: 28px;
 }
 
 #theme-choices {
diff --git a/src/librustdoc/html/static/themes/ayu.css b/src/librustdoc/html/static/themes/ayu.css
index 7374aee71f8..b24f4035ca8 100644
--- a/src/librustdoc/html/static/themes/ayu.css
+++ b/src/librustdoc/html/static/themes/ayu.css
@@ -498,7 +498,7 @@ kbd {
 	box-shadow-color: #c6cbd1;
 }
 
-#theme-picker, #settings-menu, .help-button {
+#theme-picker, #settings-menu, .help-button, #copy-path {
 	border-color: #5c6773;
 	background-color: #0f1419;
 	color: #fff;
@@ -510,7 +510,8 @@ kbd {
 
 #theme-picker:hover, #theme-picker:focus,
 #settings-menu:hover, #settings-menu:focus,
-.help-button:hover, .help-button:focus {
+.help-button:hover, .help-button:focus,
+#copy-path:hover, #copy-path:focus {
 	border-color: #e0e0e0;
 }
 
diff --git a/src/librustdoc/html/static/themes/dark.css b/src/librustdoc/html/static/themes/dark.css
index cf2d28bb43f..e863ed03f51 100644
--- a/src/librustdoc/html/static/themes/dark.css
+++ b/src/librustdoc/html/static/themes/dark.css
@@ -388,7 +388,7 @@ kbd {
 	box-shadow-color: #c6cbd1;
 }
 
-#theme-picker, #settings-menu, .help-button {
+#theme-picker, #settings-menu, .help-button, #copy-path {
 	border-color: #e0e0e0;
 	background: #f0f0f0;
 	color: #000;
@@ -396,7 +396,8 @@ kbd {
 
 #theme-picker:hover, #theme-picker:focus,
 #settings-menu:hover, #settings-menu:focus,
-.help-button:hover, .help-button:focus {
+.help-button:hover, .help-button:focus,
+#copy-path:hover, #copy-path:focus {
 	border-color: #ffb900;
 }
 
diff --git a/src/librustdoc/html/static/themes/light.css b/src/librustdoc/html/static/themes/light.css
index 7bf6793809c..9335dd96d29 100644
--- a/src/librustdoc/html/static/themes/light.css
+++ b/src/librustdoc/html/static/themes/light.css
@@ -380,14 +380,15 @@ kbd {
 	box-shadow-color: #c6cbd1;
 }
 
-#theme-picker, #settings-menu, .help-button {
+#theme-picker, #settings-menu, .help-button, #copy-path {
 	border-color: #e0e0e0;
 	background-color: #fff;
 }
 
 #theme-picker:hover, #theme-picker:focus,
 #settings-menu:hover, #settings-menu:focus,
-.help-button:hover, .help-button:focus {
+.help-button:hover, .help-button:focus,
+#copy-path:hover, #copy-path:focus {
 	border-color: #717171;
 }