rustdoc: Remove Crate.primitives

This involves no longer filtering out impls on primitive types that
aren't defined with `#[doc(primitive)]` somewhere in the dependency
graph. But, I don't think that filtering is necessary or really has any
effect.

Author: camelid

src/librustdoc/clean/types.rs

@@ -118,15 +118,14 @@ impl From<DefId> for ItemId {
 crate struct Crate {
     crate module: Item,
     crate externs: Vec<ExternalCrate>,
-    crate primitives: ThinVec<(DefId, PrimitiveType)>,
     /// Only here so that they can be filtered through the rustdoc passes.
     crate external_traits: Rc<RefCell<FxHashMap<DefId, TraitWithExtraInfo>>>,
     crate collapsed: bool,
 }
 
 // `Crate` is frequently moved by-value. Make sure it doesn't unintentionally get bigger.
 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-rustc_data_structures::static_assert_size!(Crate, 104);
+rustc_data_structures::static_assert_size!(Crate, 96);
 
 impl Crate {
     crate fn name(&self, tcx: TyCtxt<'_>) -> Symbol {

src/librustdoc/clean/utils.rs

@@ -76,13 +76,7 @@ crate fn krate(cx: &mut DocContext<'_>) -> Crate {
         }));
     }
 
-    Crate {
-        module,
-        externs,
-        primitives,
-        external_traits: cx.external_traits.clone(),
-        collapsed: false,
-    }
+    Crate { module, externs, external_traits: cx.external_traits.clone(), collapsed: false }
 }
 
 fn external_generic_args(

src/librustdoc/passes/collect_trait_impls.rs

@@ -20,8 +20,6 @@ crate fn collect_trait_impls(krate: Crate, cx: &mut DocContext<'_>) -> Crate {
         (synth.fold_crate(krate), synth.impls)
     });
 
-    let prims: FxHashSet<PrimitiveType> = krate.primitives.iter().map(|p| p.1).collect();
-
     let crate_items = {
         let mut coll = ItemCollector::new();
         krate = cx.sess().time("collect_items_for_trait_impls", || coll.fold_crate(krate));
@@ -51,7 +49,7 @@ crate fn collect_trait_impls(krate: Crate, cx: &mut DocContext<'_>) -> Crate {
         }
     }
 
-    let mut cleaner = BadImplStripper { prims, items: crate_items };
+    let mut cleaner = BadImplStripper { items: crate_items };
     let mut type_did_to_deref_target: FxHashMap<DefId, &Type> = FxHashMap::default();
 
     // Follow all `Deref` targets of included items and recursively add them as valid
@@ -62,9 +60,7 @@ crate fn collect_trait_impls(krate: Crate, cx: &mut DocContext<'_>) -> Crate {
     ) {
         if let Some(target) = map.get(&type_did) {
             debug!("add_deref_target: type {:?}, target {:?}", type_did, target);
-            if let Some(target_prim) = target.primitive_type() {
-                cleaner.prims.insert(target_prim);
-            } else if let Some(target_did) = target.def_id_no_primitives() {
+            if let Some(target_did) = target.def_id_no_primitives() {
                 // `impl Deref<Target = S> for S`
                 if target_did == type_did {
                     // Avoid infinite cycles
@@ -90,9 +86,7 @@ crate fn collect_trait_impls(krate: Crate, cx: &mut DocContext<'_>) -> Crate {
                     })
                     .expect("Deref impl without Target type");
 
-                if let Some(prim) = target.primitive_type() {
-                    cleaner.prims.insert(prim);
-                } else if let Some(did) = target.def_id(&cx.cache) {
+                if let Some(did) = target.def_id(&cx.cache) {
                     cleaner.items.insert(did.into());
                 }
                 if let Some(for_did) = for_.def_id_no_primitives() {
@@ -208,7 +202,6 @@ impl DocFolder for ItemCollector {
 }
 
 struct BadImplStripper {
-    prims: FxHashSet<PrimitiveType>,
     items: FxHashSet<ItemId>,
 }
 
@@ -217,8 +210,6 @@ impl BadImplStripper {
         if let Generic(_) = ty {
             // keep impls made on generics
             true
-        } else if let Some(prim) = ty.primitive_type() {
-            self.prims.contains(&prim)
         } else if let Some(did) = ty.def_id_no_primitives() {
             is_deref || self.keep_impl_with_def_id(did.into())
         } else {