Rollup merge of #96590 - notriddle:notriddle/tab-bar-fn-search, r=GuillaumeGomez,jsha

rustdoc: when running a function-signature search, tweak the tab bar

# Before

![In Names (7) / In Parameters (0) / In Return types (0)](https://user-images.githubusercontent.com/1593513/166122875-ffdeafe6-8d4d-4e61-84a6-f5986b50ac35.png)

# After

![In Function Signature (7)](https://user-images.githubusercontent.com/1593513/166122883-9a3d7515-3235-4ee3-8c4b-5401d109e099.png)

2 files changed, 49 insertions, 25 deletions

diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index 12059e0b9c4..eb3ce37e313 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -1333,6 +1333,11 @@ pre.rust {
 	border-top: 2px solid;
 }
 
+#titles > button:first-child:last-child {
+	margin-right: 1px;
+	width: calc(100% - 1px);
+}
+
 #titles > button:not(:last-child) {
 	margin-right: 1px;
 	width: calc(33.3% - 1px);
diff --git a/src/librustdoc/html/static/js/search.js b/src/librustdoc/html/static/js/search.js
index 54ce2508c46..02370a1243a 100644
--- a/src/librustdoc/html/static/js/search.js
+++ b/src/librustdoc/html/static/js/search.js
@@ -45,26 +45,33 @@ const TY_KEYWORD = itemTypes.indexOf("keyword");
 
 // In the search display, allows to switch between tabs.
 function printTab(nb) {
-    if (nb === 0 || nb === 1 || nb === 2) {
-        searchState.currentTab = nb;
-    }
-    let nb_copy = nb;
+    let iter = 0;
+    let foundCurrentTab = false;
+    let foundCurrentResultSet = false;
     onEachLazy(document.getElementById("titles").childNodes, elem => {
-        if (nb_copy === 0) {
+        if (nb === iter) {
             addClass(elem, "selected");
+            foundCurrentTab = true;
         } else {
             removeClass(elem, "selected");
         }
-        nb_copy -= 1;
+        iter += 1;
     });
+    iter = 0;
     onEachLazy(document.getElementById("results").childNodes, elem => {
-        if (nb === 0) {
+        if (nb === iter) {
             addClass(elem, "active");
+            foundCurrentResultSet = true;
         } else {
             removeClass(elem, "active");
         }
-        nb -= 1;
+        iter += 1;
     });
+    if (foundCurrentTab && foundCurrentResultSet) {
+        searchState.currentTab = nb;
+    } else if (nb != 0) {
+        printTab(0);
+    }
 }
 
 /**
@@ -1409,18 +1416,12 @@ window.initSearch = rawSearchIndex => {
                     for (i = 0, nSearchWords = searchWords.length; i < nSearchWords; ++i) {
                         row = searchIndex[i];
                         in_returned = checkReturned(row, elem, parsedQuery.typeFilter);
-                        addIntoResults(results_returned, row.id, i, -1, in_returned);
+                        addIntoResults(results_others, row.id, i, -1, in_returned);
                     }
                 }
             } else if (parsedQuery.foundElems > 0) {
-                let container = results_others;
-                // In the special case where only a "returned" information is available, we want to
-                // put the information into the "results_returned" dict.
-                if (parsedQuery.returned.length !== 0 && parsedQuery.elems.length === 0) {
-                    container = results_returned;
-                }
                 for (i = 0, nSearchWords = searchWords.length; i < nSearchWords; ++i) {
-                    handleArgs(searchIndex[i], i, container);
+                    handleArgs(searchIndex[i], i, results_others);
                 }
             }
         }
@@ -1725,12 +1726,26 @@ window.initSearch = rawSearchIndex => {
             `${typeFilter}</h1> in ${crates} </div>`;
         if (results.query.error !== null) {
             output += `<h3>Query parser error: "${results.query.error}".</h3>`;
+            output += '<div id="titles">' +
+                makeTabHeader(0, "In Names", ret_others[1]) +
+                "</div>";
+            currentTab = 0;
+        } else if (results.query.foundElems <= 1 && results.query.returned.length === 0) {
+            output += `<div id="titles">` +
+                makeTabHeader(0, "In Names", ret_others[1]) +
+                makeTabHeader(1, "In Parameters", ret_in_args[1]) +
+                makeTabHeader(2, "In Return Types", ret_returned[1]) +
+                "</div>";
+        } else {
+            const signatureTabTitle =
+                results.query.elems.length === 0 ? "In Function Return Types" :
+                results.query.returned.length === 0 ? "In Function Parameters" :
+                "In Function Signatures";
+            output += '<div id="titles">' +
+                makeTabHeader(0, signatureTabTitle, ret_others[1]) +
+                "</div>";
+            currentTab = 0;
         }
-        output += `<div id="titles">` +
-            makeTabHeader(0, "In Names", ret_others[1]) +
-            makeTabHeader(1, "In Parameters", ret_in_args[1]) +
-            makeTabHeader(2, "In Return Types", ret_returned[1]) +
-            "</div>";
 
         const resultsElem = document.createElement("div");
         resultsElem.id = "results";
@@ -1745,12 +1760,16 @@ window.initSearch = rawSearchIndex => {
         }
         search.appendChild(resultsElem);
         // Reset focused elements.
-        searchState.focusedByTab = [null, null, null];
         searchState.showResults(search);
         const elems = document.getElementById("titles").childNodes;
-        elems[0].onclick = () => { printTab(0); };
-        elems[1].onclick = () => { printTab(1); };
-        elems[2].onclick = () => { printTab(2); };
+        searchState.focusedByTab = [];
+        let i = 0;
+        for (const elem of elems) {
+            const j = i;
+            elem.onclick = () => { printTab(j); };
+            searchState.focusedByTab.push(null);
+            i += 1;
+        }
         printTab(currentTab);
     }