rustdoc: Elide const-unstable if also unstable overall

It's confusing because if a function is unstable overall, there's no
need to highlight the constness is also unstable. Technically, these
attributes (overall stability and const-stability) are separate, but in
practice, we don't even show the const-unstable's feature flag (it's
normally the same as the overall function).

1 files changed, 13 insertions, 8 deletions

diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index f3ae4b76883..1d0bc328641 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -1016,18 +1016,23 @@ fn render_stability_since_raw_with_extra(
                 .map(|since| (format!("const since {since}"), format!("const: {since}")))
         }
         Some(ConstStability { level: StabilityLevel::Unstable { issue, .. }, feature, .. }) => {
-            let unstable = if let Some(n) = issue {
-                format!(
-                    "<a \
+            if stable_version.is_none() {
+                // don't display const unstable if entirely unstable
+                None
+            } else {
+                let unstable = if let Some(n) = issue {
+                    format!(
+                        "<a \
                         href=\"https://github.com/rust-lang/rust/issues/{n}\" \
                         title=\"Tracking issue for {feature}\"\
                        >unstable</a>"
-                )
-            } else {
-                String::from("unstable")
-            };
+                    )
+                } else {
+                    String::from("unstable")
+                };
 
-            Some((String::from("const unstable"), format!("const: {unstable}")))
+                Some((String::from("const unstable"), format!("const: {unstable}")))
+            }
         }
         _ => None,
     };