Auto merge of #118441 - GuillaumeGomez:display-stability-version, r=<try>

Always display stability version even if it's the same as the containing item

Fixes #118439.

Currently, if the containing item's version is the same as the item's version (like a method), we don't display it on the item.

This was something done on purpose as you can see [here](https://github.com/rust-lang/rust/blob/e9b7bf011478aa8c19ac49afc99853a66ba04319/src/librustdoc/html/render/mod.rs#L949-L955). It was implemented in #30686.

I think we should change this because on pages with a lot of items, if someone arrives (through the search or a link) to an item far below the page, they won't know the stability version unless they scroll to the top, which isn't great.

You can see the result [here](https://rustdoc.crud.net/imperio/display-stability-version/std/pin/struct.Pin.html#method.new).

r? `@notriddle`

Author: bors

src/librustdoc/clean/types.rs

@@ -592,13 +592,6 @@ impl Item {
         }
     }
 
-    pub(crate) fn const_stable_since(&self, tcx: TyCtxt<'_>) -> Option<StableSince> {
-        match self.const_stability(tcx)?.level {
-            StabilityLevel::Stable { since, .. } => Some(since),
-            StabilityLevel::Unstable { .. } => None,
-        }
-    }
-
     pub(crate) fn is_non_exhaustive(&self) -> bool {
         self.attrs.other_attrs.iter().any(|a| a.has_name(sym::non_exhaustive))
     }

src/librustdoc/html/render/mod.rs

@@ -955,32 +955,20 @@ fn assoc_method(
 /// consequence of the above rules.
 fn render_stability_since_raw_with_extra(
     w: &mut Buffer,
-    ver: Option<StableSince>,
+    stable_version: Option<StableSince>,
     const_stability: Option<ConstStability>,
-    containing_ver: Option<StableSince>,
-    containing_const_ver: Option<StableSince>,
     extra_class: &str,
 ) -> bool {
-    let stable_version = if ver != containing_ver
-        && let Some(ver) = &ver
-    {
-        since_to_string(ver)
-    } else {
-        None
-    };
-
     let mut title = String::new();
     let mut stability = String::new();
 
-    if let Some(ver) = stable_version {
-        stability.push_str(ver.as_str());
-        title.push_str(&format!("Stable since Rust version {ver}"));
+    if let Some(version) = stable_version.and_then(|version| since_to_string(&version)) {
+        stability.push_str(&version);
+        title.push_str(&format!("Stable since Rust version {version}"));
     }
 
     let const_title_and_stability = match const_stability {
-        Some(ConstStability { level: StabilityLevel::Stable { since, .. }, .. })
-            if Some(since) != containing_const_ver =>
-        {
+        Some(ConstStability { level: StabilityLevel::Stable { since, .. }, .. }) => {
             since_to_string(&since)
                 .map(|since| (format!("const since {since}"), format!("const: {since}")))
         }
@@ -1035,17 +1023,8 @@ fn render_stability_since_raw(
     w: &mut Buffer,
     ver: Option<StableSince>,
     const_stability: Option<ConstStability>,
-    containing_ver: Option<StableSince>,
-    containing_const_ver: Option<StableSince>,
 ) -> bool {
-    render_stability_since_raw_with_extra(
-        w,
-        ver,
-        const_stability,
-        containing_ver,
-        containing_const_ver,
-        "",
-    )
+    render_stability_since_raw_with_extra(w, ver, const_stability, "")
 }
 
 fn render_assoc_item(
@@ -1535,7 +1514,6 @@ fn render_impl(
         cx: &mut Context<'_>,
         item: &clean::Item,
         parent: &clean::Item,
-        containing_item: &clean::Item,
         link: AssocItemLink<'_>,
         render_mode: RenderMode,
         is_default_item: bool,
@@ -1630,7 +1608,7 @@ fn render_impl(
                         })
                         .map(|item| format!("{}.{name}", item.type_()));
                     write!(w, "<section id=\"{id}\" class=\"{item_type}{in_trait_class}\">");
-                    render_rightside(w, cx, item, containing_item, render_mode);
+                    render_rightside(w, cx, item, render_mode);
                     if trait_.is_some() {
                         // Anchors are only used on trait impls.
                         write!(w, "<a href=\"#{id}\" class=\"anchor\">§</a>");
@@ -1652,7 +1630,7 @@ fn render_impl(
                 let source_id = format!("{item_type}.{name}");
                 let id = cx.derive_id(&source_id);
                 write!(w, "<section id=\"{id}\" class=\"{item_type}{in_trait_class}\">");
-                render_rightside(w, cx, item, containing_item, render_mode);
+                render_rightside(w, cx, item, render_mode);
                 if trait_.is_some() {
                     // Anchors are only used on trait impls.
                     write!(w, "<a href=\"#{id}\" class=\"anchor\">§</a>");
@@ -1738,7 +1716,6 @@ fn render_impl(
             cx,
             trait_item,
             if trait_.is_some() { &i.impl_item } else { parent },
-            parent,
             link,
             render_mode,
             false,
@@ -1754,7 +1731,6 @@ fn render_impl(
         t: &clean::Trait,
         i: &clean::Impl,
         parent: &clean::Item,
-        containing_item: &clean::Item,
         render_mode: RenderMode,
         rendering_params: ImplRenderingParameters,
     ) {
@@ -1782,7 +1758,6 @@ fn render_impl(
                 cx,
                 trait_item,
                 parent,
-                containing_item,
                 assoc_link,
                 render_mode,
                 true,
@@ -1805,7 +1780,6 @@ fn render_impl(
                 t,
                 i.inner_impl(),
                 &i.impl_item,
-                parent,
                 render_mode,
                 rendering_params,
             );
@@ -1827,7 +1801,6 @@ fn render_impl(
             cx,
             i,
             parent,
-            parent,
             rendering_params.show_def_docs,
             use_absolute,
             aliases,
@@ -1875,20 +1848,14 @@ fn render_impl(
 
 // Render the items that appear on the right side of methods, impls, and
 // associated types. For example "1.0.0 (const: 1.39.0) · source".
-fn render_rightside(
-    w: &mut Buffer,
-    cx: &Context<'_>,
-    item: &clean::Item,
-    containing_item: &clean::Item,
-    render_mode: RenderMode,
-) {
+fn render_rightside(w: &mut Buffer, cx: &Context<'_>, item: &clean::Item, render_mode: RenderMode) {
     let tcx = cx.tcx();
 
     // FIXME: Once https://github.com/rust-lang/rust/issues/67792 is implemented, we can remove
     // this condition.
-    let (const_stability, const_stable_since) = match render_mode {
-        RenderMode::Normal => (item.const_stability(tcx), containing_item.const_stable_since(tcx)),
-        RenderMode::ForDeref { .. } => (None, None),
+    let const_stability = match render_mode {
+        RenderMode::Normal => item.const_stability(tcx),
+        RenderMode::ForDeref { .. } => None,
     };
     let src_href = cx.src_href(item);
     let has_src_ref = src_href.is_some();
@@ -1898,8 +1865,6 @@ fn render_rightside(
         &mut rightside,
         item.stable_since(tcx),
         const_stability,
-        containing_item.stable_since(tcx),
-        const_stable_since,
         if has_src_ref { "" } else { " rightside" },
     );
     if let Some(link) = src_href {
@@ -1921,7 +1886,6 @@ pub(crate) fn render_impl_summary(
     cx: &mut Context<'_>,
     i: &Impl,
     parent: &clean::Item,
-    containing_item: &clean::Item,
     show_def_docs: bool,
     use_absolute: Option<bool>,
     // This argument is used to reference same type with different paths to avoid duplication
@@ -1936,7 +1900,7 @@ pub(crate) fn render_impl_summary(
         format!(" data-aliases=\"{}\"", aliases.join(","))
     };
     write!(w, "<section id=\"{id}\" class=\"impl\"{aliases}>");
-    render_rightside(w, cx, &i.impl_item, containing_item, RenderMode::Normal);
+    render_rightside(w, cx, &i.impl_item, RenderMode::Normal);
     write!(
         w,
         "<a href=\"#{id}\" class=\"anchor\">§</a>\

src/librustdoc/html/render/print_item.rs

@@ -224,8 +224,6 @@ pub(super) fn print_item(
         &mut stability_since_raw,
         item.stable_since(cx.tcx()),
         item.const_stability(cx.tcx()),
-        None,
-        None,
     );
     let stability_since_raw: String = stability_since_raw.into_inner();
 
@@ -847,7 +845,7 @@ fn item_trait(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, t: &clean:
             write!(w, "<details class=\"toggle{method_toggle_class}\" open><summary>");
         }
         write!(w, "<section id=\"{id}\" class=\"method\">");
-        render_rightside(w, cx, m, t, RenderMode::Normal);
+        render_rightside(w, cx, m, RenderMode::Normal);
         write!(w, "<h4 class=\"code-header\">");
         render_assoc_item(
             w,
@@ -1708,8 +1706,6 @@ fn item_variants(
             w,
             variant.stable_since(tcx),
             variant.const_stability(tcx),
-            it.stable_since(tcx),
-            it.const_stable_since(tcx),
             " rightside",
         );
         w.write_str("<h3 class=\"code-header\">");

tests/rustdoc/const-display.rs

@@ -72,8 +72,8 @@ impl Foo {
 pub struct Bar;
 
 impl Bar {
-    // Do not show non-const stabilities that are the same as the enclosing item.
-    // @matches 'foo/struct.Bar.html' '//span[@class="since"]' '^const: 1.2.0$'
+    // Show non-const stabilities that are the same as the enclosing item.
+    // @has 'foo/struct.Bar.html' '//span[@class="since"]' '1.0.0 (const: 1.2.0)'
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const2", since = "1.2.0")]
     pub const fn stable_impl() -> u32 { 42 }

tests/rustdoc/deref/deref-const-fn.rs

@@ -26,7 +26,7 @@ pub struct Foo {
 
 // @has 'foo/struct.Foo.html'
 // @has - '//*[@id="method.len"]' 'pub fn len(&self) -> usize'
-// @!has - '//*[@id="method.len"]//span[@class="since"]' '1.0.0'
+// @has - '//*[@id="method.len"]//span[@class="since"]' '1.0.0'
 // @!has - '//*[@id="method.len"]//span[@class="since"]' '(const: 1.0.0)'
 #[stable(feature = "rust1", since = "1.0.0")]
 impl std::ops::Deref for Foo {

tests/rustdoc/ensure-src-link.rs

@@ -2,5 +2,5 @@
 
 // This test ensures that the [src] link is present on traits items.
 
-// @has foo/trait.Iterator.html '//*[@id="method.zip"]//a[@class="src rightside"]' "source"
+// @has foo/trait.Iterator.html '//*[@id="method.zip"]//a[@class="src"]' "source"
 pub use std::iter::Iterator;

tests/rustdoc/implementor-stable-version.rs

@@ -16,6 +16,6 @@ pub struct Foo;
 #[stable(feature = "foobar", since = "4.4.4")]
 impl Bar for Foo {}
 
-// @!has foo/trait.Baz.html '//div[@id="implementors-list"]//span[@class="since"]' '3.3.3'
+// @has foo/trait.Baz.html '//div[@id="implementors-list"]//span[@class="since"]' '3.3.3'
 #[stable(feature = "foobaz", since = "3.3.3")]
 impl Baz for Foo {}