Auto merge of #103119 - matthiaskrgr:rollup-2vb8hif, r=matthiaskrgr

Rollup of 4 pull requests

Successful merges:

 - #102857 (Add a regression test for #39137)
 - #102953 (Improve docs for `struct_lint_level` function.)
 - #103060 (rustdoc: make the help button a link to a page)
 - #103115 (Clean up anchors.goml rustdoc GUI test)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

Diff for: compiler/rustc_lint/src/context.rs

@@ -574,6 +574,11 @@ pub trait LintContext: Sized {
     fn sess(&self) -> &Session;
     fn lints(&self) -> &LintStore;
 
+    /// Emit a lint at the appropriate level, with an optional associated span and an existing diagnostic.
+    ///
+    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
+    ///
+    /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     fn lookup_with_diagnostics(
         &self,
         lint: &'static Lint,
@@ -872,6 +877,11 @@ pub trait LintContext: Sized {
 
     // FIXME: These methods should not take an Into<MultiSpan> -- instead, callers should need to
     // set the span in their `decorate` function (preferably using set_span).
+    /// Emit a lint at the appropriate level, with an optional associated span.
+    ///
+    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
+    ///
+    /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     fn lookup<S: Into<MultiSpan>>(
         &self,
         lint: &'static Lint,
@@ -893,6 +903,11 @@ pub trait LintContext: Sized {
         self.lookup(lint, Some(span), decorator.msg(), |diag| decorator.decorate_lint(diag));
     }
 
+    /// Emit a lint at the appropriate level, with an associated span.
+    ///
+    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
+    ///
+    /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     fn struct_span_lint<S: Into<MultiSpan>>(
         &self,
         lint: &'static Lint,
@@ -914,6 +929,10 @@ pub trait LintContext: Sized {
     }
 
     /// Emit a lint at the appropriate level, with no associated span.
+    ///
+    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
+    ///
+    /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     fn lint(
         &self,
         lint: &'static Lint,

Diff for: compiler/rustc_lint/src/levels.rs

@@ -1069,6 +1069,10 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
 
     /// Used to emit a lint-related diagnostic based on the current state of
     /// this lint context.
+    ///
+    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
+    ///
+    /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     pub(crate) fn struct_lint(
         &self,
         lint: &'static Lint,

Diff for: compiler/rustc_middle/src/lint.rs

@@ -274,6 +274,39 @@ pub fn explain_lint_level_source(
     }
 }
 
+/// The innermost function for emitting lints.
+///
+/// If you are loocking to implement a lint, look for higher level functions,
+/// for example:
+/// - [`TyCtxt::emit_spanned_lint`]
+/// - [`TyCtxt::struct_span_lint_hir`]
+/// - [`TyCtxt::emit_lint`]
+/// - [`TyCtxt::struct_lint_node`]
+/// - `LintContext::lookup`
+///
+/// ## `decorate` signature
+///
+/// The return value of `decorate` is ignored by this function. So what is the
+/// point of returning `&'b mut DiagnosticBuilder<'a, ()>`?
+///
+/// There are 2 reasons for this signature.
+///
+/// First of all, it prevents accidental use of `.emit()` -- it's clear that the
+/// builder will be later used and shouldn't be emitted right away (this is
+/// especially important because the old API expected you to call `.emit()` in
+/// the closure).
+///
+/// Second of all, it makes the most common case of adding just a single label
+/// /suggestion much nicer, since [`DiagnosticBuilder`] methods return
+/// `&mut DiagnosticBuilder`, you can just chain methods, without needed
+/// awkward `{ ...; }`:
+/// ```ignore pseudo-code
+/// struct_lint_level(
+///     ...,
+///     |lint| lint.span_label(sp, "lbl")
+///     //          ^^^^^^^^^^^^^^^^^^^^^ returns `&mut DiagnosticBuilder` by default
+/// )
+/// ```
 pub fn struct_lint_level(
     sess: &Session,
     lint: &'static Lint,

Diff for: compiler/rustc_middle/src/ty/context.rs

@@ -2823,6 +2823,11 @@ impl<'tcx> TyCtxt<'tcx> {
         })
     }
 
+    /// Emit a lint at the appropriate level for a hir node, with an associated span.
+    ///
+    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
+    ///
+    /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     pub fn struct_span_lint_hir(
         self,
         lint: &'static Lint,
@@ -2848,6 +2853,11 @@ impl<'tcx> TyCtxt<'tcx> {
         self.struct_lint_node(lint, id, decorator.msg(), |diag| decorator.decorate_lint(diag))
     }
 
+    /// Emit a lint at the appropriate level for a hir node.
+    ///
+    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
+    ///
+    /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     pub fn struct_lint_node(
         self,
         lint: &'static Lint,

Diff for: src/ci/docker/host-x86_64/x86_64-gnu-tools/browser-ui-test.version

@@ -1 +1 @@
-0.12.4
+0.12.5

Diff for: src/librustdoc/html/markdown.rs

@@ -1433,6 +1433,7 @@ static DEFAULT_ID_MAP: Lazy<FxHashMap<Cow<'static, str>, usize>> = Lazy::new(||
 fn init_id_map() -> FxHashMap<Cow<'static, str>, usize> {
     let mut map = FxHashMap::default();
     // This is the list of IDs used in Javascript.
+    map.insert("help".into(), 1);
     map.insert("settings".into(), 1);
     map.insert("not-displayed".into(), 1);
     map.insert("alternative-display".into(), 1);

Diff for: src/librustdoc/html/render/context.rs

@@ -581,6 +581,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
         let crate_name = self.tcx().crate_name(LOCAL_CRATE);
         let final_file = self.dst.join(crate_name.as_str()).join("all.html");
         let settings_file = self.dst.join("settings.html");
+        let help_file = self.dst.join("help.html");
         let scrape_examples_help_file = self.dst.join("scrape-examples-help.html");
 
         let mut root_path = self.dst.to_str().expect("invalid path").to_owned();
@@ -657,6 +658,39 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
         );
         shared.fs.write(settings_file, v)?;
 
+        // Generating help page.
+        page.title = "Rustdoc help";
+        page.description = "Documentation for Rustdoc";
+        page.root_path = "./";
+
+        let sidebar = "<h2 class=\"location\">Help</h2><div class=\"sidebar-elems\"></div>";
+        let v = layout::render(
+            &shared.layout,
+            &page,
+            sidebar,
+            |buf: &mut Buffer| {
+                write!(
+                    buf,
+                    "<div class=\"main-heading\">\
+                     <h1 class=\"fqn\">Rustdoc help</h1>\
+                     <span class=\"out-of-band\">\
+                         <a id=\"back\" href=\"javascript:void(0)\" onclick=\"history.back();\">\
+                            Back\
+                        </a>\
+                     </span>\
+                     </div>\
+                     <noscript>\
+                        <section>\
+                            <p>You need to enable Javascript to use keyboard commands or search.</p>\
+                            <p>For more information, browse the <a href=\"https://doc.rust-lang.org/rustdoc/\">rustdoc handbook</a>.</p>\
+                        </section>\
+                     </noscript>",
+                )
+            },
+            &shared.style_files,
+        );
+        shared.fs.write(help_file, v)?;
+
         if shared.layout.scrape_examples_extension {
             page.title = "About scraped examples";
             page.description = "How the scraped examples feature works in Rustdoc";

Diff for: src/librustdoc/html/static/css/rustdoc.css

@@ -199,7 +199,7 @@ h1, h2, h3, h4, h5, h6,
 .out-of-band,
 span.since,
 a.srclink,
-#help-button > button,
+#help-button > a,
 details.rustdoc-toggle.top-doc > summary,
 details.rustdoc-toggle.non-exhaustive > summary,
 .scraped-example-title,
@@ -974,32 +974,33 @@ so that we can apply CSS-filters to change the arrow color in themes */
 	color: var(--main-color);
 }
 
-#help-button .popover {
+/* use larger max-width for help popover, but not for help.html */
+#help.popover {
 	max-width: 600px;
 }
 
-#help-button .popover::before {
+#help.popover::before {
 	right: 48px;
 }
 
-#help-button dt {
+#help dt {
 	float: left;
 	clear: left;
 	display: block;
 	margin-right: 0.5rem;
 }
-#help-button span.top, #help-button span.bottom {
+#help span.top, #help span.bottom {
 	text-align: center;
 	display: block;
 	font-size: 1.125rem;
 }
-#help-button span.top {
+#help span.top {
 	margin: 10px 0;
 	border-bottom: 1px solid var(--border-color);
 	padding-bottom: 4px;
 	margin-bottom: 6px;
 }
-#help-button span.bottom {
+#help span.bottom {
 	clear: both;
 	border-top: 1px solid var(--border-color);
 }
@@ -1433,7 +1434,7 @@ h3.variant {
 	outline: none;
 }
 
-#settings-menu > a, #help-button > button, #copy-path {
+#settings-menu > a, #help-button > a, #copy-path {
 	padding: 5px;
 	width: 33px;
 	border: 1px solid var(--border-color);
@@ -1442,7 +1443,7 @@ h3.variant {
 	line-height: 1.5;
 }
 
-#settings-menu > a, #help-button > button {
+#settings-menu > a, #help-button > a {
 	padding: 5px;
 	height: 100%;
 	display: block;
@@ -1490,7 +1491,7 @@ input:checked + .slider {
 	background-color: var(--settings-input-color);
 }
 
-#help-button > button {
+#help-button > a {
 	text-align: center;
 	/* Rare exception to specifying font sizes in rem. Since this is acting
 	   as an icon, it's okay to specify their sizes in pixels. */

Diff for: src/librustdoc/html/static/css/themes/ayu.css

@@ -248,7 +248,7 @@ kbd {
 	box-shadow: inset 0 -1px 0 #5c6773;
 }
 
-#settings-menu > a, #help-button > button {
+#settings-menu > a, #help-button > a {
 	color: #fff;
 }
 
@@ -257,7 +257,7 @@ kbd {
 }
 
 #settings-menu > a:hover, #settings-menu > a:focus,
-#help-button > button:hover, #help-button > button:focus {
+#help-button > a:hover, #help-button > a:focus {
 	border-color: #e0e0e0;
 }
 

Diff for: src/librustdoc/html/static/css/themes/dark.css

@@ -153,12 +153,12 @@ kbd {
 	box-shadow: inset 0 -1px 0 #c6cbd1;
 }
 
-#settings-menu > a, #help-button > button {
+#settings-menu > a, #help-button > a {
 	color: #000;
 }
 
 #settings-menu > a:hover, #settings-menu > a:focus,
-#help-button > button:hover, #help-button > button:focus {
+#help-button > a:hover, #help-button > a:focus {
 	border-color: #ffb900;
 }
 

Diff for: src/librustdoc/html/static/css/themes/light.css

@@ -147,8 +147,12 @@ kbd {
 	box-shadow: inset 0 -1px 0 #c6cbd1;
 }
 
+#settings-menu > a, #help-button > a {
+	color: #000;
+}
+
 #settings-menu > a:hover, #settings-menu > a:focus,
-#help-button > button:hover, #help-button > button:focus {
+#help-button > a:hover, #help-button > a:focus {
 	border-color: #717171;
 }