Rollup merge of rust-lang#120596 - GuillaumeGomez:jump-to-def-non-local-link, r=notriddle

[rustdoc] Correctly generate path for non-local items in source code pages

While browsing some crates using the "jump to def" feature, I realized that a lot of items didn't have a link generated. The reason is because we only cache foreign items if they appear in the documented API. This means that for the others, we need to infer them.

r? ``@notriddle``

Author: matthiaskrgr

src/librustdoc/clean/inline.rs

@@ -191,15 +191,28 @@ pub(crate) fn load_attrs<'hir>(cx: &DocContext<'hir>, did: DefId) -> &'hir [ast:
     cx.tcx.get_attrs_unchecked(did)
 }
 
+pub(crate) fn item_relative_path(tcx: TyCtxt<'_>, def_id: DefId) -> Vec<Symbol> {
+    tcx.def_path(def_id)
+        .data
+        .into_iter()
+        .filter_map(|elem| {
+            // extern blocks (and a few others things) have an empty name.
+            match elem.data.get_opt_name() {
+                Some(s) if !s.is_empty() => Some(s),
+                _ => None,
+            }
+        })
+        .collect()
+}
+
 /// Record an external fully qualified name in the external_paths cache.
 ///
 /// These names are used later on by HTML rendering to generate things like
 /// source links back to the original item.
 pub(crate) fn record_extern_fqn(cx: &mut DocContext<'_>, did: DefId, kind: ItemType) {
     let crate_name = cx.tcx.crate_name(did.krate);
 
-    let relative =
-        cx.tcx.def_path(did).data.into_iter().filter_map(|elem| elem.data.get_opt_name());
+    let relative = item_relative_path(cx.tcx, did);
     let fqn = if let ItemType::Macro = kind {
         // Check to see if it is a macro 2.0 or built-in macro
         if matches!(
@@ -210,7 +223,7 @@ pub(crate) fn record_extern_fqn(cx: &mut DocContext<'_>, did: DefId, kind: ItemT
         ) {
             once(crate_name).chain(relative).collect()
         } else {
-            vec![crate_name, relative.last().expect("relative was empty")]
+            vec![crate_name, *relative.last().expect("relative was empty")]
         }
     } else {
         once(crate_name).chain(relative).collect()

src/librustdoc/formats/item_type.rs

@@ -4,7 +4,7 @@ use std::fmt;
 
 use serde::{Serialize, Serializer};
 
-use rustc_hir::def::DefKind;
+use rustc_hir::def::{CtorOf, DefKind};
 use rustc_span::hygiene::MacroKind;
 
 use crate::clean;
@@ -115,7 +115,15 @@ impl<'a> From<&'a clean::Item> for ItemType {
 
 impl From<DefKind> for ItemType {
     fn from(other: DefKind) -> Self {
-        match other {
+        Self::from_def_kind(other, None)
+    }
+}
+
+impl ItemType {
+    /// Depending on the parent kind, some variants have a different translation (like a `Method`
+    /// becoming a `TyMethod`).
+    pub(crate) fn from_def_kind(kind: DefKind, parent_kind: Option<DefKind>) -> Self {
+        match kind {
             DefKind::Enum => Self::Enum,
             DefKind::Fn => Self::Function,
             DefKind::Mod => Self::Module,
@@ -131,30 +139,35 @@ impl From<DefKind> for ItemType {
                 MacroKind::Attr => ItemType::ProcAttribute,
                 MacroKind::Derive => ItemType::ProcDerive,
             },
-            DefKind::ForeignTy
-            | DefKind::Variant
-            | DefKind::AssocTy
-            | DefKind::TyParam
+            DefKind::ForeignTy => Self::ForeignType,
+            DefKind::Variant => Self::Variant,
+            DefKind::Field => Self::StructField,
+            DefKind::AssocTy => Self::AssocType,
+            DefKind::AssocFn => {
+                if let Some(DefKind::Trait) = parent_kind {
+                    Self::TyMethod
+                } else {
+                    Self::Method
+                }
+            }
+            DefKind::Ctor(CtorOf::Struct, _) => Self::Struct,
+            DefKind::Ctor(CtorOf::Variant, _) => Self::Variant,
+            DefKind::AssocConst => Self::AssocConst,
+            DefKind::TyParam
             | DefKind::ConstParam
-            | DefKind::Ctor(..)
-            | DefKind::AssocFn
-            | DefKind::AssocConst
             | DefKind::ExternCrate
             | DefKind::Use
             | DefKind::ForeignMod
             | DefKind::AnonConst
             | DefKind::InlineConst
             | DefKind::OpaqueTy
-            | DefKind::Field
             | DefKind::LifetimeParam
             | DefKind::GlobalAsm
             | DefKind::Impl { .. }
             | DefKind::Closure => Self::ForeignType,
         }
     }
-}
 
-impl ItemType {
     pub(crate) fn as_str(&self) -> &'static str {
         match *self {
             ItemType::Module => "mod",

src/librustdoc/html/format.rs

@@ -32,6 +32,7 @@ use crate::clean::{
     self, types::ExternalLocation, utils::find_nearest_parent_module, ExternalCrate, ItemId,
     PrimitiveType,
 };
+use crate::formats::cache::Cache;
 use crate::formats::item_type::ItemType;
 use crate::html::escape::Escape;
 use crate::html::render::Context;
@@ -581,22 +582,11 @@ fn generate_macro_def_id_path(
     cx: &Context<'_>,
     root_path: Option<&str>,
 ) -> Result<(String, ItemType, Vec<Symbol>), HrefError> {
-    let tcx = cx.shared.tcx;
+    let tcx = cx.tcx();
     let crate_name = tcx.crate_name(def_id.krate);
     let cache = cx.cache();
 
-    let fqp: Vec<Symbol> = tcx
-        .def_path(def_id)
-        .data
-        .into_iter()
-        .filter_map(|elem| {
-            // extern blocks (and a few others things) have an empty name.
-            match elem.data.get_opt_name() {
-                Some(s) if !s.is_empty() => Some(s),
-                _ => None,
-            }
-        })
-        .collect();
+    let fqp = clean::inline::item_relative_path(tcx, def_id);
     let mut relative = fqp.iter().copied();
     let cstore = CStore::from_tcx(tcx);
     // We need this to prevent a `panic` when this function is used from intra doc links...
@@ -651,92 +641,168 @@ fn generate_macro_def_id_path(
     Ok((url, ItemType::Macro, fqp))
 }
 
+fn generate_item_def_id_path(
+    mut def_id: DefId,
+    original_def_id: DefId,
+    cx: &Context<'_>,
+    root_path: Option<&str>,
+    original_def_kind: DefKind,
+) -> Result<(String, ItemType, Vec<Symbol>), HrefError> {
+    use crate::rustc_trait_selection::infer::TyCtxtInferExt;
+    use crate::rustc_trait_selection::traits::query::normalize::QueryNormalizeExt;
+    use rustc_middle::traits::ObligationCause;
+
+    let tcx = cx.tcx();
+    let crate_name = tcx.crate_name(def_id.krate);
+
+    // No need to try to infer the actual parent item if it's not an associated item from the `impl`
+    // block.
+    if def_id != original_def_id && matches!(tcx.def_kind(def_id), DefKind::Impl { .. }) {
+        let infcx = tcx.infer_ctxt().build();
+        def_id = infcx
+            .at(&ObligationCause::dummy(), tcx.param_env(def_id))
+            .query_normalize(ty::Binder::dummy(tcx.type_of(def_id).instantiate_identity()))
+            .map(|resolved| infcx.resolve_vars_if_possible(resolved.value))
+            .ok()
+            .and_then(|normalized| normalized.skip_binder().ty_adt_def())
+            .map(|adt| adt.did())
+            .unwrap_or(def_id);
+    }
+
+    let relative = clean::inline::item_relative_path(tcx, def_id);
+    let fqp: Vec<Symbol> = once(crate_name).chain(relative).collect();
+
+    let def_kind = tcx.def_kind(def_id);
+    let shortty = def_kind.into();
+    let module_fqp = to_module_fqp(shortty, &fqp);
+    let mut is_remote = false;
+
+    let url_parts = url_parts(cx.cache(), def_id, &module_fqp, &cx.current, &mut is_remote)?;
+    let (url_parts, shortty, fqp) = make_href(root_path, shortty, url_parts, &fqp, is_remote)?;
+    if def_id == original_def_id {
+        return Ok((url_parts, shortty, fqp));
+    }
+    let kind = ItemType::from_def_kind(original_def_kind, Some(def_kind));
+    Ok((format!("{url_parts}#{kind}.{}", tcx.item_name(original_def_id)), shortty, fqp))
+}
+
+fn to_module_fqp(shortty: ItemType, fqp: &[Symbol]) -> &[Symbol] {
+    if shortty == ItemType::Module { fqp } else { &fqp[..fqp.len() - 1] }
+}
+
+fn url_parts(
+    cache: &Cache,
+    def_id: DefId,
+    module_fqp: &[Symbol],
+    relative_to: &[Symbol],
+    is_remote: &mut bool,
+) -> Result<UrlPartsBuilder, HrefError> {
+    match cache.extern_locations[&def_id.krate] {
+        ExternalLocation::Remote(ref s) => {
+            *is_remote = true;
+            let s = s.trim_end_matches('/');
+            let mut builder = UrlPartsBuilder::singleton(s);
+            builder.extend(module_fqp.iter().copied());
+            Ok(builder)
+        }
+        ExternalLocation::Local => Ok(href_relative_parts(module_fqp, relative_to).collect()),
+        ExternalLocation::Unknown => Err(HrefError::DocumentationNotBuilt),
+    }
+}
+
+fn make_href(
+    root_path: Option<&str>,
+    shortty: ItemType,
+    mut url_parts: UrlPartsBuilder,
+    fqp: &[Symbol],
+    is_remote: bool,
+) -> Result<(String, ItemType, Vec<Symbol>), HrefError> {
+    if !is_remote && let Some(root_path) = root_path {
+        let root = root_path.trim_end_matches('/');
+        url_parts.push_front(root);
+    }
+    debug!(?url_parts);
+    match shortty {
+        ItemType::Module => {
+            url_parts.push("index.html");
+        }
+        _ => {
+            let prefix = shortty.as_str();
+            let last = fqp.last().unwrap();
+            url_parts.push_fmt(format_args!("{prefix}.{last}.html"));
+        }
+    }
+    Ok((url_parts.finish(), shortty, fqp.to_vec()))
+}
+
 pub(crate) fn href_with_root_path(
-    did: DefId,
+    original_did: DefId,
     cx: &Context<'_>,
     root_path: Option<&str>,
 ) -> Result<(String, ItemType, Vec<Symbol>), HrefError> {
     let tcx = cx.tcx();
-    let def_kind = tcx.def_kind(did);
+    let def_kind = tcx.def_kind(original_did);
     let did = match def_kind {
         DefKind::AssocTy | DefKind::AssocFn | DefKind::AssocConst | DefKind::Variant => {
             // documented on their parent's page
-            tcx.parent(did)
+            tcx.parent(original_did)
         }
+        // If this a constructor, we get the parent (either a struct or a variant) and then
+        // generate the link for this item.
+        DefKind::Ctor(..) => return href_with_root_path(tcx.parent(original_did), cx, root_path),
         DefKind::ExternCrate => {
             // Link to the crate itself, not the `extern crate` item.
-            if let Some(local_did) = did.as_local() {
+            if let Some(local_did) = original_did.as_local() {
                 tcx.extern_mod_stmt_cnum(local_did).unwrap_or(LOCAL_CRATE).as_def_id()
             } else {
-                did
+                original_did
             }
         }
-        _ => did,
+        _ => original_did,
     };
     let cache = cx.cache();
     let relative_to = &cx.current;
-    fn to_module_fqp(shortty: ItemType, fqp: &[Symbol]) -> &[Symbol] {
-        if shortty == ItemType::Module { fqp } else { &fqp[..fqp.len() - 1] }
-    }
 
-    if !did.is_local()
-        && !cache.effective_visibilities.is_directly_public(tcx, did)
-        && !cache.document_private
-        && !cache.primitive_locations.values().any(|&id| id == did)
-    {
-        return Err(HrefError::Private);
+    if !original_did.is_local() {
+        // If we are generating an href for the "jump to def" feature, then the only case we want
+        // to ignore is if the item is `doc(hidden)` because we can't link to it.
+        if root_path.is_some() {
+            if tcx.is_doc_hidden(original_did) {
+                return Err(HrefError::Private);
+            }
+        } else if !cache.effective_visibilities.is_directly_public(tcx, did)
+            && !cache.document_private
+            && !cache.primitive_locations.values().any(|&id| id == did)
+        {
+            return Err(HrefError::Private);
+        }
     }
 
     let mut is_remote = false;
-    let (fqp, shortty, mut url_parts) = match cache.paths.get(&did) {
+    let (fqp, shortty, url_parts) = match cache.paths.get(&did) {
         Some(&(ref fqp, shortty)) => (fqp, shortty, {
             let module_fqp = to_module_fqp(shortty, fqp.as_slice());
             debug!(?fqp, ?shortty, ?module_fqp);
             href_relative_parts(module_fqp, relative_to).collect()
         }),
         None => {
-            if let Some(&(ref fqp, shortty)) = cache.external_paths.get(&did) {
+            // Associated items are handled differently with "jump to def". The anchor is generated
+            // directly here whereas for intra-doc links, we have some extra computation being
+            // performed there.
+            let def_id_to_get = if root_path.is_some() { original_did } else { did };
+            if let Some(&(ref fqp, shortty)) = cache.external_paths.get(&def_id_to_get) {
                 let module_fqp = to_module_fqp(shortty, fqp);
-                (
-                    fqp,
-                    shortty,
-                    match cache.extern_locations[&did.krate] {
-                        ExternalLocation::Remote(ref s) => {
-                            is_remote = true;
-                            let s = s.trim_end_matches('/');
-                            let mut builder = UrlPartsBuilder::singleton(s);
-                            builder.extend(module_fqp.iter().copied());
-                            builder
-                        }
-                        ExternalLocation::Local => {
-                            href_relative_parts(module_fqp, relative_to).collect()
-                        }
-                        ExternalLocation::Unknown => return Err(HrefError::DocumentationNotBuilt),
-                    },
-                )
+                (fqp, shortty, url_parts(cache, did, module_fqp, relative_to, &mut is_remote)?)
             } else if matches!(def_kind, DefKind::Macro(_)) {
                 return generate_macro_def_id_path(did, cx, root_path);
+            } else if did.is_local() {
+                return Err(HrefError::Private);
             } else {
-                return Err(HrefError::NotInExternalCache);
+                return generate_item_def_id_path(did, original_did, cx, root_path, def_kind);
             }
         }
     };
-    if !is_remote && let Some(root_path) = root_path {
-        let root = root_path.trim_end_matches('/');
-        url_parts.push_front(root);
-    }
-    debug!(?url_parts);
-    match shortty {
-        ItemType::Module => {
-            url_parts.push("index.html");
-        }
-        _ => {
-            let prefix = shortty.as_str();
-            let last = fqp.last().unwrap();
-            url_parts.push_fmt(format_args!("{prefix}.{last}.html"));
-        }
-    }
-    Ok((url_parts.finish(), shortty, fqp.to_vec()))
+    make_href(root_path, shortty, url_parts, fqp, is_remote)
 }
 
 pub(crate) fn href(