Auto merge of #131076 - lukas-code:doc-stab2, r=notriddle

rustdoc: rewrite stability inheritance as a doc pass

Since doc inlining can almost arbitrarily change the module hierarchy, we can't just use the HIR ancestors of an item to compute its effective stability. This PR moves the stability inheritance that I implemented in https://github.com/rust-lang/rust/pull/130798 into a new doc pass `propagate-stability` that runs after doc inlining and uses the post-inlining ancestors of an item to correctly compute its effective stability.

fixes https://github.com/rust-lang/rust/issues/131020

r? `@notriddle`

1 files changed, 12 insertions, 19 deletions

diff --git a/src/librustdoc/html/render/print_item.rs b/src/librustdoc/html/render/print_item.rs
index d120e7f36eb..38276e4d20c 100644
--- a/src/librustdoc/html/render/print_item.rs
+++ b/src/librustdoc/html/render/print_item.rs
@@ -436,16 +436,9 @@ fn item_module(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Item, items:
             }
 
             clean::ImportItem(ref import) => {
-                let stab_tags = if let Some(import_def_id) = import.source.did {
-                    // Just need an item with the correct def_id and attrs
-                    let import_item =
-                        clean::Item { item_id: import_def_id.into(), ..(*myitem).clone() };
-
-                    let stab_tags = Some(extra_info_tags(&import_item, item, tcx).to_string());
-                    stab_tags
-                } else {
-                    None
-                };
+                let stab_tags = import.source.did.map_or_else(String::new, |import_def_id| {
+                    extra_info_tags(tcx, myitem, item, Some(import_def_id)).to_string()
+                });
 
                 w.write_str(ITEM_TABLE_ROW_OPEN);
                 let id = match import.kind {
@@ -454,7 +447,6 @@ fn item_module(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Item, items:
                     }
                     clean::ImportKind::Glob => String::new(),
                 };
-                let stab_tags = stab_tags.unwrap_or_default();
                 let (stab_tags_before, stab_tags_after) = if stab_tags.is_empty() {
                     ("", "")
                 } else {
@@ -521,7 +513,7 @@ fn item_module(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Item, items:
                      {docs_before}{docs}{docs_after}",
                     name = EscapeBodyTextWithWbr(myitem.name.unwrap().as_str()),
                     visibility_and_hidden = visibility_and_hidden,
-                    stab_tags = extra_info_tags(myitem, item, tcx),
+                    stab_tags = extra_info_tags(tcx, myitem, item, None),
                     class = myitem.type_(),
                     unsafety_flag = unsafety_flag,
                     href = item_path(myitem.type_(), myitem.name.unwrap().as_str()),
@@ -544,9 +536,10 @@ fn item_module(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Item, items:
 /// Render the stability, deprecation and portability tags that are displayed in the item's summary
 /// at the module level.
 fn extra_info_tags<'a, 'tcx: 'a>(
+    tcx: TyCtxt<'tcx>,
     item: &'a clean::Item,
     parent: &'a clean::Item,
-    tcx: TyCtxt<'tcx>,
+    import_def_id: Option<DefId>,
 ) -> impl fmt::Display + 'a + Captures<'tcx> {
     display_fn(move |f| {
         fn tag_html<'a>(
@@ -564,18 +557,18 @@ fn extra_info_tags<'a, 'tcx: 'a>(
         }
 
         // The trailing space after each tag is to space it properly against the rest of the docs.
-        if let Some(depr) = &item.deprecation(tcx) {
+        let deprecation = import_def_id
+            .map_or_else(|| item.deprecation(tcx), |import_did| tcx.lookup_deprecation(import_did));
+        if let Some(depr) = deprecation {
             let message = if depr.is_in_effect() { "Deprecated" } else { "Deprecation planned" };
             write!(f, "{}", tag_html("deprecated", "", message))?;
         }
 
         // The "rustc_private" crates are permanently unstable so it makes no sense
         // to render "unstable" everywhere.
-        if item
-            .stability(tcx)
-            .as_ref()
-            .is_some_and(|s| s.is_unstable() && s.feature != sym::rustc_private)
-        {
+        let stability = import_def_id
+            .map_or_else(|| item.stability(tcx), |import_did| tcx.lookup_stability(import_did));
+        if stability.is_some_and(|s| s.is_unstable() && s.feature != sym::rustc_private) {
             write!(f, "{}", tag_html("unstable", "", "Experimental"))?;
         }