From 1129e8678038cfc938559b90b4155dde8b84edf3 Mon Sep 17 00:00:00 2001
From: LeSeulArtichaut <leseulartichaut@gmail.com>
Date: Sat, 23 Jan 2021 18:05:59 +0100
Subject: [PATCH 1/2] Cleanup `render_stability_since_raw` to remove code
 duplication

---
 src/librustdoc/html/render/mod.rs | 43 ++++++++++++-------------------
 1 file changed, 17 insertions(+), 26 deletions(-)

diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index 26afd705740b2..f15d43b7b1600 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -2934,34 +2934,25 @@ fn render_stability_since_raw(
     containing_ver: Option<&str>,
     containing_const_ver: Option<&str>,
 ) {
-    let ver = ver.and_then(|inner| if !inner.is_empty() { Some(inner) } else { None });
+    let ver = ver.filter(|inner| !inner.is_empty());
+    let const_ver = const_ver.filter(|inner| !inner.is_empty());
 
-    let const_ver = const_ver.and_then(|inner| if !inner.is_empty() { Some(inner) } else { None });
-
-    if let Some(v) = ver {
-        if let Some(cv) = const_ver {
-            if const_ver != containing_const_ver {
-                write!(
-                    w,
-                    "<span class=\"since\" title=\"Stable since Rust version {0}, const since {1}\">{0} (const: {1})</span>",
-                    v, cv
-                );
-            } else if ver != containing_ver {
-                write!(
-                    w,
-                    "<span class=\"since\" title=\"Stable since Rust version {0}\">{0}</span>",
-                    v
-                );
-            }
-        } else {
-            if ver != containing_ver {
-                write!(
-                    w,
-                    "<span class=\"since\" title=\"Stable since Rust version {0}\">{0}</span>",
-                    v
-                );
-            }
+    match (ver, const_ver) {
+        (Some(v), Some(cv)) if const_ver != containing_const_ver => {
+            write!(
+                w,
+                "<span class=\"since\" title=\"Stable since Rust version {0}, const since {1}\">{0} (const: {1})</span>",
+                v, cv
+            );
+        }
+        (Some(v), _) if ver != containing_ver => {
+            write!(
+                w,
+                "<span class=\"since\" title=\"Stable since Rust version {0}\">{0}</span>",
+                v
+            );
         }
+        _ => {}
     }
 }
 

From 20a460e1cf23262b46a7e9672a02c5f07b91eff5 Mon Sep 17 00:00:00 2001
From: LeSeulArtichaut <leseulartichaut@gmail.com>
Date: Sat, 23 Jan 2021 18:41:04 +0100
Subject: [PATCH 2/2] Fix rendering of stabilization version for trait
 implementors

---
 src/librustdoc/html/render/mod.rs             |  8 ++++----
 .../rustdoc/implementor-stable-version.rs     | 19 +++++++++++++++++++
 2 files changed, 23 insertions(+), 4 deletions(-)
 create mode 100644 src/test/rustdoc/implementor-stable-version.rs

diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index f15d43b7b1600..bfaadc38763c3 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -2471,7 +2471,7 @@ fn item_function(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, f: &clean::
 fn render_implementor(
     cx: &Context<'_>,
     implementor: &Impl,
-    parent: &clean::Item,
+    trait_: &clean::Item,
     w: &mut Buffer,
     implementor_dups: &FxHashMap<Symbol, (DefId, bool)>,
     aliases: &[String],
@@ -2491,11 +2491,11 @@ fn render_implementor(
         w,
         cx,
         implementor,
-        parent,
+        trait_,
         AssocItemLink::Anchor(None),
         RenderMode::Normal,
-        implementor.impl_item.stable_since(cx.tcx()).as_deref(),
-        implementor.impl_item.const_stable_since(cx.tcx()).as_deref(),
+        trait_.stable_since(cx.tcx()).as_deref(),
+        trait_.const_stable_since(cx.tcx()).as_deref(),
         false,
         Some(use_absolute),
         false,
diff --git a/src/test/rustdoc/implementor-stable-version.rs b/src/test/rustdoc/implementor-stable-version.rs
new file mode 100644
index 0000000000000..0a065d8095bf2
--- /dev/null
+++ b/src/test/rustdoc/implementor-stable-version.rs
@@ -0,0 +1,19 @@
+#![crate_name = "foo"]
+
+#![feature(staged_api)]
+
+#[stable(feature = "bar", since = "OLD 1.0")]
+pub trait Bar {}
+
+#[stable(feature = "baz", since = "OLD 1.0")]
+pub trait Baz {}
+
+pub struct Foo;
+
+// @has foo/trait.Bar.html '//div[@id="implementors-list"]//span[@class="since"]' 'NEW 2.0'
+#[stable(feature = "foobar", since = "NEW 2.0")]
+impl Bar for Foo {}
+
+// @!has foo/trait.Baz.html '//div[@id="implementors-list"]//span[@class="since"]' 'OLD 1.0'
+#[stable(feature = "foobaz", since = "OLD 1.0")]
+impl Baz for Foo {}