Rollup merge of #130706 - GuillaumeGomez:remove-unneeded-jinja-comments, r=notriddle

[rustdoc] Remove unneeded jinja comments

This is a follow-up of https://github.com/rust-lang/rust/pull/130585.

Since we now check for the jinja comments we missed, we can now check for the jinja comments which are unneeded. It will make the parsing and therefore the compilation a tiny bit faster (well, if anyone sees a difference haha). The real goal is mostly to have easier to read template files. :wink:

r? ``@notriddle``

8 files changed, 83 insertions, 51 deletions

diff --git a/src/librustdoc/html/templates/item_info.html b/src/librustdoc/html/templates/item_info.html
index 9e65ae95e15..9fee268622e 100644
--- a/src/librustdoc/html/templates/item_info.html
+++ b/src/librustdoc/html/templates/item_info.html
@@ -1,7 +1,7 @@
 {% if !items.is_empty() %}
     <span class="item-info">
         {% for item in items %}
-            {{item|safe}} {# #}
+            {{item|safe}}
         {% endfor %}
     </span>
 {% endif %}
diff --git a/src/librustdoc/html/templates/page.html b/src/librustdoc/html/templates/page.html
index 65c4304e202..a05d6ca8313 100644
--- a/src/librustdoc/html/templates/page.html
+++ b/src/librustdoc/html/templates/page.html
@@ -12,13 +12,13 @@
     <link rel="stylesheet" {#+ #}
           href="{{static_root_path|safe}}{{files.normalize_css}}"> {# #}
     <link rel="stylesheet" {#+ #}
-          href="{{static_root_path|safe}}{{files.rustdoc_css}}"> {# #}
+          href="{{static_root_path|safe}}{{files.rustdoc_css}}">
     {% if !layout.default_settings.is_empty() %}
     <script id="default-settings" {#+ #}
       {%~ for (k, v) in layout.default_settings ~%}
         data-{{k}}="{{v}}"
       {% endfor %}
-    ></script> {# #}
+    ></script>
     {% endif %}
     <meta name="rustdoc-vars" {#+ #}
          data-root-path="{{page.root_path|safe}}" {#+ #}
@@ -31,36 +31,36 @@
          data-search-js="{{files.search_js}}" {#+ #}
          data-settings-js="{{files.settings_js}}" {#+ #}
     > {# #}
-    <script src="{{static_root_path|safe}}{{files.storage_js}}"></script> {# #}
+    <script src="{{static_root_path|safe}}{{files.storage_js}}"></script>
     {% if page.css_class.contains("crate") %}
-    <script defer src="{{page.root_path|safe}}crates{{page.resource_suffix}}.js"></script> {# #}
+    <script defer src="{{page.root_path|safe}}crates{{page.resource_suffix}}.js"></script>
     {% else if page.css_class == "src" %}
     <script defer src="{{static_root_path|safe}}{{files.src_script_js}}"></script> {# #}
-    <script defer src="{{page.root_path|safe}}src-files{{page.resource_suffix}}.js"></script> {# #}
+    <script defer src="{{page.root_path|safe}}src-files{{page.resource_suffix}}.js"></script>
     {% else if !page.css_class.contains("mod") %}
-    <script defer src="sidebar-items{{page.resource_suffix}}.js"></script> {# #}
+    <script defer src="sidebar-items{{page.resource_suffix}}.js"></script>
     {% else if !page.css_class.contains("sys") %}
-    <script defer src="../sidebar-items{{page.resource_suffix}}.js"></script> {# #}
+    <script defer src="../sidebar-items{{page.resource_suffix}}.js"></script>
     {% endif %}
-    <script defer src="{{static_root_path|safe}}{{files.main_js}}"></script> {# #}
+    <script defer src="{{static_root_path|safe}}{{files.main_js}}"></script>
     {% if layout.scrape_examples_extension %}
-    <script defer src="{{static_root_path|safe}}{{files.scrape_examples_js}}"></script> {# #}
+    <script defer src="{{static_root_path|safe}}{{files.scrape_examples_js}}"></script>
     {% endif %}
     <noscript> {# #}
         <link rel="stylesheet" {#+ #}
            href="{{static_root_path|safe}}{{files.noscript_css}}"> {# #}
-    </noscript> {# #}
+    </noscript>
     {% if layout.css_file_extension.is_some() %}
         <link rel="stylesheet" {#+ #}
-            href="{{page.root_path|safe}}theme{{page.resource_suffix}}.css"> {# #}
+            href="{{page.root_path|safe}}theme{{page.resource_suffix}}.css">
     {% endif %}
     {% if !layout.favicon.is_empty() %}
-        <link rel="icon" href="{{layout.favicon}}"> {# #}
+        <link rel="icon" href="{{layout.favicon}}">
     {% else %}
         <link rel="alternate icon" type="image/png" {#+ #}
             href="{{static_root_path|safe}}{{files.rust_favicon_png_32}}"> {# #}
         <link rel="icon" type="image/svg+xml" {#+ #}
-            href="{{static_root_path|safe}}{{files.rust_favicon_svg}}"> {# #}
+            href="{{static_root_path|safe}}{{files.rust_favicon_svg}}">
     {% endif %}
     {{ layout.external_html.in_header|safe }}
 </head> {# #}
@@ -69,60 +69,60 @@
     <div class="warning"> {# #}
         This old browser is unsupported and will most likely display funky things. {# #}
     </div> {# #}
-    <![endif]--> {# #}
+    <![endif]-->
     {{ layout.external_html.before_content|safe }}
     {% if page.css_class != "src" %}
     <nav class="mobile-topbar"> {# #}
-        <button class="sidebar-menu-toggle" title="show sidebar"></button> {# #}
+        <button class="sidebar-menu-toggle" title="show sidebar"></button>
         {% if !layout.logo.is_empty() || page.rust_logo %}
-        <a class="logo-container" href="{{page.root_path|safe}}{{display_krate_with_trailing_slash|safe}}index.html"> {# #}
+        <a class="logo-container" href="{{page.root_path|safe}}{{display_krate_with_trailing_slash|safe}}index.html">
         {% if page.rust_logo %}
-            <img class="rust-logo" src="{{static_root_path|safe}}{{files.rust_logo_svg}}" alt=""> {# #}
+            <img class="rust-logo" src="{{static_root_path|safe}}{{files.rust_logo_svg}}" alt="">
         {% else if !layout.logo.is_empty() %}
-            <img src="{{layout.logo}}" alt=""> {# #}
+            <img src="{{layout.logo}}" alt="">
         {% endif %}
-        </a> {# #}
+        </a>
         {% endif %}
     </nav>
     {% endif %}
-    <nav class="sidebar"> {# #}
+    <nav class="sidebar">
         {% if page.css_class != "src" %}
         <div class="sidebar-crate">
             {% if !layout.logo.is_empty() || page.rust_logo %}
-            <a class="logo-container" href="{{page.root_path|safe}}{{display_krate_with_trailing_slash|safe}}index.html"> {# #}
+            <a class="logo-container" href="{{page.root_path|safe}}{{display_krate_with_trailing_slash|safe}}index.html">
                 {% if page.rust_logo %}
-                    <img class="rust-logo" src="{{static_root_path|safe}}{{files.rust_logo_svg}}" alt="logo"> {# #}
+                    <img class="rust-logo" src="{{static_root_path|safe}}{{files.rust_logo_svg}}" alt="logo">
                 {% else if !layout.logo.is_empty() %}
-                    <img src="{{layout.logo}}" alt="logo"> {# #}
+                    <img src="{{layout.logo}}" alt="logo">
                 {% endif %}
-            </a> {# #}
+            </a>
             {% endif %}
             <h2> {# #}
-                <a href="{{page.root_path|safe}}{{display_krate_with_trailing_slash|safe}}index.html">{{display_krate|wrapped|safe}}</a> {# #}
+                <a href="{{page.root_path|safe}}{{display_krate_with_trailing_slash|safe}}index.html">{{display_krate|wrapped|safe}}</a>
                 {% if !display_krate_version_number.is_empty() %}
                     <span class="version">{{+ display_krate_version_number}}</span>
                 {% endif %}
             </h2> {# #}
-        </div> {# #}
+        </div>
         {% if !display_krate_version_extra.is_empty() %}
-        <div class="version">{{+ display_krate_version_extra}}</div> {# #}
+        <div class="version">{{+ display_krate_version_extra}}</div>
         {% endif %}
         {% else %}
         <div class="src-sidebar-title"> {# #}
             <h2>Files</h2> {# #}
-        </div> {# #}
+        </div>
         {% endif %}
         {{ sidebar|safe }}
     </nav> {# #}
     <div class="sidebar-resizer"></div> {# #}
-    <main> {# #}
+    <main>
         {% if page.css_class != "src" %}<div class="width-limiter">{% endif %}
             {# defined in storage.js to avoid duplicating complex UI across every page #}
             {# and because the search form only works if JS is enabled anyway #}
             <rustdoc-search></rustdoc-search> {# #}
-            <section id="main-content" class="content">{{ content|safe }}</section> {# #}
+            <section id="main-content" class="content">{{ content|safe }}</section>
         {% if page.css_class != "src" %}</div>{% endif %}
-    </main> {# #}
+    </main>
     {{ layout.external_html.after_content|safe }}
 </body> {# #}
 </html> {# #}
diff --git a/src/librustdoc/html/templates/print_item.html b/src/librustdoc/html/templates/print_item.html
index 32ded1fbe42..f60720b67c6 100644
--- a/src/librustdoc/html/templates/print_item.html
+++ b/src/librustdoc/html/templates/print_item.html
@@ -1,4 +1,4 @@
-<div class="main-heading"> {# #}
+<div class="main-heading">
     {% if !path_components.is_empty() %}
     <span class="rustdoc-breadcrumbs">
         {% for (i, component) in path_components.iter().enumerate() %}
diff --git a/src/librustdoc/html/templates/short_item_info.html b/src/librustdoc/html/templates/short_item_info.html
index 75d155e91c2..e76b98541cf 100644
--- a/src/librustdoc/html/templates/short_item_info.html
+++ b/src/librustdoc/html/templates/short_item_info.html
@@ -3,21 +3,21 @@
         <div class="stab deprecated"> {# #}
             <span class="emoji">👎</span> {# #}
             <span>{{message|safe}}</span> {# #}
-        </div> {# #}
+        </div>
     {% when Self::Unstable with { feature, tracking } %}
         <div class="stab unstable"> {# #}
             <span class="emoji">🔬</span> {# #}
             <span> {# #}
                 This is a nightly-only experimental API. ({# #}
-                <code>{{feature}}</code> {# #}
+                <code>{{feature}}</code>
                 {% match tracking %}
                     {% when Some with ((url, num)) %}
-                        &nbsp;<a href="{{url}}{{num}}">#{{num}}</a> {# #}
+                        &nbsp;<a href="{{url}}{{num}}">#{{num}}</a>
                     {% when None %}
                 {% endmatch %}
                 ) {# #}
             </span> {# #}
-        </div> {# #}
+        </div>
     {% when Self::Portability with { message } %}
-        <div class="stab portability">{{message|safe}}</div> {# #}
+        <div class="stab portability">{{message|safe}}</div>
 {% endmatch %}
diff --git a/src/librustdoc/html/templates/sidebar.html b/src/librustdoc/html/templates/sidebar.html
index fccf65cbefc..7f852b489fa 100644
--- a/src/librustdoc/html/templates/sidebar.html
+++ b/src/librustdoc/html/templates/sidebar.html
@@ -30,7 +30,7 @@
                                             {% else %}
                                                 {{link.name}}
                                         {% endmatch %}
-                                    </a> {# #}
+                                    </a>
                                     {% if !link.children.is_empty() %}
                                         <ul>
                                             {% for child in link.children %}
diff --git a/src/librustdoc/html/templates/source.html b/src/librustdoc/html/templates/source.html
index 9daa0cf8ff6..ea530087e6f 100644
--- a/src/librustdoc/html/templates/source.html
+++ b/src/librustdoc/html/templates/source.html
@@ -9,7 +9,7 @@
 </div>
 {% else %}
 {% endmatch %}
-<div class="example-wrap"> {# #}
+<div class="example-wrap">
     {# https://developers.google.com/search/docs/crawling-indexing/robots-meta-tag#data-nosnippet-attr
        Do not show "1 2 3 4 5 ..." in web search results. #}
     <div data-nosnippet><pre class="src-line-numbers">
diff --git a/src/librustdoc/html/templates/type_layout.html b/src/librustdoc/html/templates/type_layout.html
index e0516bb42fe..aee96fb8c41 100644
--- a/src/librustdoc/html/templates/type_layout.html
+++ b/src/librustdoc/html/templates/type_layout.html
@@ -1,7 +1,7 @@
 <h2 id="layout" class="section-header"> {# #}
     Layout<a href="#layout" class="anchor">§</a> {# #}
 </h2> {# #}
-<div class="docblock"> {# #}
+<div class="docblock">
     {% match type_layout_size %}
     {% when Ok(type_layout_size) %}
     <div class="warning"> {# #}
@@ -14,19 +14,19 @@
             chapter for details on type layout guarantees. {# #}
         </p> {# #}
     </div> {# #}
-    <p><strong>Size:</strong> {{+ type_layout_size|safe }}</p> {# #}
+    <p><strong>Size:</strong> {{+ type_layout_size|safe }}</p>
     {% if !variants.is_empty() %}
     <p> {# #}
         <strong>Size for each variant:</strong> {# #}
     </p> {# #}
-    <ul> {# #}
+    <ul>
         {% for (name, layout_size) in variants %}
         <li> {# #}
             <code>{{ name }}</code>: {#+ #}
             {{ layout_size|safe }}
-        </li> {# #}
+        </li>
         {% endfor %}
-    </ul> {# #}
+    </ul>
     {% endif %}
     {# This kind of layout error can occur with valid code, e.g. if you try to
     get the layout of a generic type such as `Vec<T>`. #}
@@ -35,7 +35,7 @@
             <strong>Note:</strong> Unable to compute type layout, {#+ #}
             possibly due to this type having generic parameters. {#+ #}
             Layout can only be computed for concrete, fully-instantiated types. {# #}
-        </p> {# #}
+        </p>
         {# This kind of error probably can't happen with valid code, but we don't
         want to panic and prevent the docs from building, so we just let the
         user know that we couldn't compute the layout. #}
@@ -43,21 +43,21 @@
         <p> {# #}
             <strong>Note:</strong> Encountered an error during type layout; {#+ #}
             the type was too big. {# #}
-        </p> {# #}
+        </p>
         {% when Err(LayoutError::ReferencesError(_)) %}
         <p> {# #}
             <strong>Note:</strong> Encountered an error during type layout; {#+ #}
             the type references errors. {# #}
-        </p> {# #}
+        </p>
         {% when Err(LayoutError::NormalizationFailure(_, _)) %}
         <p> {# #}
             <strong>Note:</strong> Encountered an error during type layout; {#+ #}
             the type failed to be normalized. {# #}
-        </p> {# #}
+        </p>
         {% when Err(LayoutError::Cycle(_)) %}
         <p> {# #}
             <strong>Note:</strong> Encountered an error during type layout; {#+ #}
             the type's layout depended on the type's layout itself. {# #}
-        </p> {# #}
+        </p>
         {% endmatch %}
 </div> {# #}
diff --git a/src/tools/tidy/src/rustdoc_templates.rs b/src/tools/tidy/src/rustdoc_templates.rs
index 6c8530e6366..2173dbf7e74 100644
--- a/src/tools/tidy/src/rustdoc_templates.rs
+++ b/src/tools/tidy/src/rustdoc_templates.rs
@@ -20,7 +20,39 @@ pub fn check(librustdoc_path: &Path, bad: &mut bool) {
 
             while let Some((pos, line)) = lines.next() {
                 let line = line.trim();
-                if TAGS.iter().any(|(_, tag)| line.ends_with(tag)) {
+                if let Some(need_next_line_check) = TAGS.iter().find_map(|(tag, end_tag)| {
+                    // We first check if the line ends with a jinja tag.
+                    if !line.ends_with(end_tag) {
+                        return None;
+                    // Then we check if this a comment tag.
+                    } else if *tag != "{#" {
+                        return Some(false);
+                    // And finally we check if the comment is empty (ie, only there to strip
+                    // extra whitespace characters).
+                    } else if let Some(start_pos) = line.rfind(tag) {
+                        Some(line[start_pos + 2..].trim() == "#}")
+                    } else {
+                        Some(false)
+                    }
+                }) {
+                    // All good, the line is ending is a jinja tag. But maybe this tag is useless
+                    // if the next line starts with a jinja tag as well!
+                    //
+                    // However, only (empty) comment jinja tags are concerned about it.
+                    if need_next_line_check
+                        && lines.peek().is_some_and(|(_, next_line)| {
+                            let next_line = next_line.trim_start();
+                            TAGS.iter().any(|(tag, _)| next_line.starts_with(tag))
+                        })
+                    {
+                        // It seems like ending this line with a jinja tag is not needed after all.
+                        tidy_error!(
+                            bad,
+                            "`{}` at line {}: unneeded `{{# #}}` tag at the end of the line",
+                            path.path().display(),
+                            pos + 1,
+                        );
+                    }
                     continue;
                 }
                 let Some(next_line) = lines.peek().map(|(_, next_line)| next_line.trim()) else {