Ignore rustc_private items from std docs

Apply suggestions from code review

Co-authored-by: Joshua Nelson <joshua@yottadb.com>

src/librustdoc/clean/inline.rs

@@ -337,18 +337,13 @@ pub fn build_impl(
     // reachable in rustdoc generated documentation
     if !did.is_local() {
         if let Some(traitref) = associated_trait {
-            if !cx.renderinfo.borrow().access_levels.is_public(traitref.def_id) {
+            let did = traitref.def_id;
+            if !cx.renderinfo.borrow().access_levels.is_public(did) {
                 return;
             }
-        }
 
-        // Skip foreign unstable traits from lists of trait implementations and
-        // such. This helps prevent dependencies of the standard library, for
-        // example, from getting documented as "traits `u32` implements" which
-        // isn't really too helpful.
-        if let Some(trait_did) = associated_trait {
-            if let Some(stab) = cx.tcx.lookup_stability(trait_did.def_id) {
-                if stab.level.is_unstable() {
+            if let Some(stab) = tcx.lookup_stability(did) {
+                if stab.level.is_unstable() && stab.feature == sym::rustc_private {
                     return;
                 }
             }
@@ -372,6 +367,12 @@ pub fn build_impl(
             if !cx.renderinfo.borrow().access_levels.is_public(did) {
                 return;
             }
+
+            if let Some(stab) = tcx.lookup_stability(did) {
+                if stab.level.is_unstable() && stab.feature == sym::rustc_private {
+                    return;
+                }
+            }
         }
     }
 

src/tools/linkchecker/main.rs

@@ -142,6 +142,16 @@ fn is_exception(file: &Path, link: &str) -> bool {
     if let Some(entry) = LINKCHECK_EXCEPTIONS.iter().find(|&(f, _)| file.ends_with(f)) {
         entry.1.contains(&link)
     } else {
+        // FIXME(#63351): Concat trait in alloc/slice reexported in primitive page
+        //
+        // NOTE: This cannot be added to `LINKCHECK_EXCEPTIONS` because the resolved path
+        // calculated in `check` function is outside `build/<triple>/doc` dir.
+        // So the `strip_prefix` method just returns the old absolute broken path.
+        if file.ends_with("std/primitive.slice.html") {
+            if link.ends_with("std/primitive.slice.html") {
+                return true;
+            }
+        }
         false
     }
 }