1 files changed, 101 insertions, 0 deletions
diff --git a/src/librustdoc/formats/mod.rs b/src/librustdoc/formats/mod.rs
new file mode 100644
index 000000000..b236bd7be
--- /dev/null
+++ b/src/librustdoc/formats/mod.rs
@@ -0,0 +1,101 @@
+pub(crate) mod cache;
+pub(crate) mod item_type;
+pub(crate) mod renderer;
+
+use rustc_hir::def_id::DefId;
+
+pub(crate) use renderer::{run_format, FormatRenderer};
+
+use crate::clean::{self, ItemId};
+use crate::html::render::Context;
+
+/// Specifies whether rendering directly implemented trait items or ones from a certain Deref
+/// impl.
+pub(crate) enum AssocItemRender<'a> {
+    All,
+    DerefFor { trait_: &'a clean::Path, type_: &'a clean::Type, deref_mut_: bool },
+}
+
+/// For different handling of associated items from the Deref target of a type rather than the type
+/// itself.
+#[derive(Copy, Clone, PartialEq)]
+pub(crate) enum RenderMode {
+    Normal,
+    ForDeref { mut_: bool },
+}
+
+/// Metadata about implementations for a type or trait.
+#[derive(Clone, Debug)]
+pub(crate) struct Impl {
+    pub(crate) impl_item: clean::Item,
+}
+
+impl Impl {
+    pub(crate) fn inner_impl(&self) -> &clean::Impl {
+        match *self.impl_item.kind {
+            clean::ImplItem(ref impl_) => impl_,
+            _ => panic!("non-impl item found in impl"),
+        }
+    }
+
+    pub(crate) fn trait_did(&self) -> Option<DefId> {
+        self.inner_impl().trait_.as_ref().map(|t| t.def_id())
+    }
+
+    /// This function is used to extract a `DefId` to be used as a key for the `Cache::impls` field.
+    ///
+    /// It allows to prevent having duplicated implementations showing up (the biggest issue was
+    /// with blanket impls).
+    ///
+    /// It panics if `self` is a `ItemId::Primitive`.
+    pub(crate) fn def_id(&self) -> DefId {
+        match self.impl_item.item_id {
+            ItemId::Blanket { impl_id, .. } => impl_id,
+            ItemId::Auto { trait_, .. } => trait_,
+            ItemId::DefId(def_id) => def_id,
+            ItemId::Primitive(_, _) => {
+                panic!(
+                    "Unexpected ItemId::Primitive in expect_def_id: {:?}",
+                    self.impl_item.item_id
+                )
+            }
+        }
+    }
+
+    // Returns true if this is an implementation on a "local" type, meaning:
+    // the type is in the current crate, or the type and the trait are both
+    // re-exported by the current crate.
+    pub(crate) fn is_on_local_type(&self, cx: &Context<'_>) -> bool {
+        let cache = cx.cache();
+        let for_type = &self.inner_impl().for_;
+        if let Some(for_type_did) = for_type.def_id(cache) {
+            // The "for" type is local if it's in the paths for the current crate.
+            if cache.paths.contains_key(&for_type_did) {
+                return true;
+            }
+            if let Some(trait_did) = self.trait_did() {
+                // The "for" type and the trait are from the same crate. That could
+                // be different from the current crate, for instance when both were
+                // re-exported from some other crate. But they are local with respect to
+                // each other.
+                if for_type_did.krate == trait_did.krate {
+                    return true;
+                }
+                // Hack: many traits and types in std are re-exported from
+                // core or alloc. In general, rustdoc is capable of recognizing
+                // these implementations as being on local types. However, in at
+                // least one case (https://github.com/rust-lang/rust/issues/97610),
+                // rustdoc gets confused and labels an implementation as being on
+                // a foreign type. To make sure that confusion doesn't pass on to
+                // the reader, consider all implementations in std, core, and alloc
+                // to be on local types.
+                let crate_name = cx.tcx().crate_name(trait_did.krate);
+                if matches!(crate_name.as_str(), "std" | "core" | "alloc") {
+                    return true;
+                }
+            }
+            return false;
+        };
+        true
+    }
+}