From 19edb3ce808ee2b1190026b9d56cc6187e1ad9b1 Mon Sep 17 00:00:00 2001 From: Michael Howell Date: Thu, 24 Aug 2023 20:44:32 -0700 Subject: [PATCH] rustdoc: list matching impls on type aliases Remake of "List matching impls on type aliases" * 4b1d13d9841c815915433ca2a3088a8e3e97ad96 * 6f552c800b38b3e71c5e33a295e8b490d2018c71 * 2ce7cd906bde70d8cbd9b07b31c6a7bf1131c345 Partially reverts "Fix infinite loop when retrieving impls for type alias", but keeps the test case. This version of the PR avoids the infinite loop by structurally matching types instead of using full unification. This version does not support type alias trait bounds, but the compiler does not enforce those anyway (https://github.com/rust-lang/rust/issues/21903). --- src/librustdoc/html/render/mod.rs | 47 +++++++++++++-- tests/rustdoc/issue-32077-type-alias-impls.rs | 59 +++++++++++++++++++ 2 files changed, 102 insertions(+), 4 deletions(-) create mode 100644 tests/rustdoc/issue-32077-type-alias-impls.rs diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs index aef8f1a74fb5a..1d77ce74c80ea 100644 --- a/src/librustdoc/html/render/mod.rs +++ b/src/librustdoc/html/render/mod.rs @@ -54,6 +54,7 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_hir::def_id::{DefId, DefIdSet}; use rustc_hir::Mutability; use rustc_middle::middle::stability; +use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams}; use rustc_middle::ty::TyCtxt; use rustc_span::{ symbol::{sym, Symbol}, @@ -62,6 +63,7 @@ use rustc_span::{ use serde::ser::{SerializeMap, SerializeSeq}; use serde::{Serialize, Serializer}; +use crate::clean::types::TypeAliasItem; use crate::clean::{self, ItemId, RenderedLink, SelfTy}; use crate::error::Error; use crate::formats::cache::Cache; @@ -1139,8 +1141,40 @@ fn render_assoc_items_inner( info!("Documenting associated items of {:?}", containing_item.name); let shared = Rc::clone(&cx.shared); let cache = &shared.cache; - let Some(v) = cache.impls.get(&it) else { return }; - let (non_trait, traits): (Vec<_>, _) = v.iter().partition(|i| i.inner_impl().trait_.is_none()); + let tcx = cx.tcx(); + let av = if let TypeAliasItem(ait) = &*containing_item.kind && + let aliased_clean_type = ait.item_type.as_ref().unwrap_or(&ait.type_) && + let Some(aliased_type_defid) = aliased_clean_type.def_id(cache) && + let Some(mut av) = cache.impls.get(&aliased_type_defid).cloned() && + let Some(alias_def_id) = containing_item.item_id.as_def_id() + { + // This branch of the compiler compares types structually, but does + // not check trait bounds. That's probably fine, since type aliases + // don't normally constrain on them anyway. + // https://github.com/rust-lang/rust/issues/21903 + // + // If that changes, then this will need to check them with type + // unification. + let aliased_ty = tcx.type_of(alias_def_id).skip_binder(); + let reject_cx = DeepRejectCtxt { + treat_obligation_params: TreatParams::AsCandidateKey, + }; + av.retain(|impl_| { + if let Some(impl_def_id) = impl_.impl_item.item_id.as_def_id() { + reject_cx.types_may_unify(aliased_ty, tcx.type_of(impl_def_id).skip_binder()) + } else { + false + } + }); + av + } else { + Vec::new() + }; + let blank = Vec::new(); + let v = cache.impls.get(&it).unwrap_or(&blank); + let (non_trait, traits): (Vec<_>, _) = + v.iter().chain(&av[..]).partition(|i| i.inner_impl().trait_.is_none()); + let mut saw_impls = FxHashSet::default(); if !non_trait.is_empty() { let mut tmp_buf = Buffer::html(); let (render_mode, id, class_html) = match what { @@ -1169,6 +1203,9 @@ fn render_assoc_items_inner( }; let mut impls_buf = Buffer::html(); for i in &non_trait { + if !saw_impls.insert(i.def_id()) { + continue; + } render_impl( &mut impls_buf, cx, @@ -1214,8 +1251,10 @@ fn render_assoc_items_inner( let (synthetic, concrete): (Vec<&Impl>, Vec<&Impl>) = traits.into_iter().partition(|t| t.inner_impl().kind.is_auto()); - let (blanket_impl, concrete): (Vec<&Impl>, _) = - concrete.into_iter().partition(|t| t.inner_impl().kind.is_blanket()); + let (blanket_impl, concrete): (Vec<&Impl>, _) = concrete + .into_iter() + .filter(|t| saw_impls.insert(t.def_id())) + .partition(|t| t.inner_impl().kind.is_blanket()); render_all_impls(w, cx, containing_item, &concrete, &synthetic, &blanket_impl); } diff --git a/tests/rustdoc/issue-32077-type-alias-impls.rs b/tests/rustdoc/issue-32077-type-alias-impls.rs new file mode 100644 index 0000000000000..555d0579bee79 --- /dev/null +++ b/tests/rustdoc/issue-32077-type-alias-impls.rs @@ -0,0 +1,59 @@ +// Regression test for . + +#![crate_name = "foo"] + +pub struct GenericStruct(T); + +impl GenericStruct { + pub fn on_gen(arg: T) {} +} + +impl GenericStruct { + pub fn on_u32(arg: u32) {} +} + +pub trait Foo {} +pub trait Bar {} + +impl Foo for GenericStruct {} +impl Bar for GenericStruct {} + +// @has 'foo/type.TypedefStruct.html' +// We check that we have the implementation of the type alias itself. +// @has - '//*[@id="impl-TypedefStruct"]/h3' 'impl TypedefStruct' +// @has - '//*[@id="method.on_alias"]/h4' 'pub fn on_alias()' +// @has - '//*[@id="impl-GenericStruct%3CT%3E"]/h3' 'impl GenericStruct' +// @has - '//*[@id="method.on_gen"]/h4' 'pub fn on_gen(arg: T)' +// @has - '//*[@id="impl-Foo-for-GenericStruct%3CT%3E"]/h3' 'impl Foo for GenericStruct' +// This trait implementation doesn't match the type alias parameters so shouldn't appear in docs. +// @!has - '//h3' 'impl Bar for GenericStruct {}' +// Same goes for the `Deref` impl. +// @!has - '//h2' 'Methods from Deref' +pub type TypedefStruct = GenericStruct; + +impl TypedefStruct { + pub fn on_alias() {} +} + +impl std::ops::Deref for GenericStruct { + type Target = u32; + + fn deref(&self) -> &Self::Target { + &self.0 + } +} + +pub struct Wrap(GenericStruct); + +// @has 'foo/type.Alias.html' +// @has - '//h2' 'Methods from Deref' +// @has - '//*[@id="impl-Deref-for-Wrap%3CT%3E"]/h3' 'impl Deref for Wrap' +pub type Alias = Wrap; + +impl std::ops::Deref for Wrap { + type Target = GenericStruct; + + fn deref(&self) -> &Self::Target { + &self.0 + } +}