Add tests for recursive deref

7 files changed, 169 insertions, 8 deletions

diff --git a/src/librustdoc/passes/collect_trait_impls.rs b/src/librustdoc/passes/collect_trait_impls.rs
index d559dd4effe..b306eb98bb5 100644
--- a/src/librustdoc/passes/collect_trait_impls.rs
+++ b/src/librustdoc/passes/collect_trait_impls.rs
@@ -81,8 +81,8 @@ crate fn collect_trait_impls(krate: Crate, cx: &mut DocContext<'_>) -> Crate {
     // scan through included items ahead of time to splice in Deref targets to the "valid" sets
     for it in &new_items {
         if let ImplItem(Impl { ref for_, ref trait_, ref items, .. }) = *it.kind {
-            if cleaner.keep_impl(for_)
-                && trait_.as_ref().map(|t| t.def_id()) == cx.tcx.lang_items().deref_trait()
+            if trait_.as_ref().map(|t| t.def_id()) == cx.tcx.lang_items().deref_trait()
+                && cleaner.keep_impl(for_)
             {
                 let target = items
                     .iter()
@@ -221,8 +221,11 @@ impl BadImplStripper {
             true
         } else if let Some(prim) = ty.primitive_type() {
             self.prims.contains(&prim)
-        } else if let Some(did) = ty.def_id_no_primitives() {
-            self.keep_impl_with_def_id(did.into())
+        } else if ty.def_id_no_primitives().is_some() {
+            // We want to keep *ALL* deref implementations in case some of them are used in
+            // the current crate.
+            // FIXME: Try to filter the one actually used...
+            true
         } else {
             false
         }
diff --git a/src/test/rustdoc-ui/recursive-deref-ice.rs b/src/test/rustdoc-ui/recursive-deref-ice.rs
new file mode 100644
index 00000000000..c44fd27f403
--- /dev/null
+++ b/src/test/rustdoc-ui/recursive-deref-ice.rs
@@ -0,0 +1,19 @@
+// check-pass
+
+// ICE found in https://github.com/rust-lang/rust/issues/83123
+
+pub struct Attribute;
+
+pub struct Map<'hir> {}
+impl<'hir> Map<'hir> {
+    pub fn attrs(&self) -> &'hir [Attribute] { &[] }
+}
+
+pub struct List<T>(T);
+
+impl<T> std::ops::Deref for List<T> {
+    type Target = [T];
+    fn deref(&self) -> &[T] {
+        &[]
+    }
+}
diff --git a/src/test/rustdoc/deref-recursive-pathbuf.rs b/src/test/rustdoc/deref-recursive-pathbuf.rs
new file mode 100644
index 00000000000..ac23eced386
--- /dev/null
+++ b/src/test/rustdoc/deref-recursive-pathbuf.rs
@@ -0,0 +1,24 @@
+// #26207: Show all methods reachable via Deref impls, recursing through multiple dereferencing
+// levels and across multiple crates.
+
+// @has 'foo/struct.Foo.html'
+// @has '-' '//*[@id="deref-methods-PathBuf"]' 'Methods from Deref<Target = PathBuf>'
+// @has '-' '//*[@class="impl-items"]//*[@id="method.as_path"]' 'pub fn as_path(&self)'
+// @has '-' '//*[@id="deref-methods-Path"]' 'Methods from Deref<Target = Path>'
+// @has '-' '//*[@class="impl-items"]//*[@id="method.exists"]' 'pub fn exists(&self)'
+// @has '-' '//*[@class="sidebar-title"]/a[@href="#deref-methods-PathBuf"]' 'Methods from Deref<Target=PathBuf>'
+// @has '-' '//*[@class="sidebar-links"]/a[@href="#method.as_path"]' 'as_path'
+// @has '-' '//*[@class="sidebar-title"]/a[@href="#deref-methods-Path"]' 'Methods from Deref<Target=Path>'
+// @has '-' '//*[@class="sidebar-links"]/a[@href="#method.exists"]' 'exists'
+
+#![crate_name = "foo"]
+
+use std::ops::Deref;
+use std::path::PathBuf;
+
+pub struct Foo(PathBuf);
+
+impl Deref for Foo {
+    type Target = PathBuf;
+    fn deref(&self) -> &PathBuf { &self.0 }
+}
diff --git a/src/test/rustdoc/deref-recursive.rs b/src/test/rustdoc/deref-recursive.rs
new file mode 100644
index 00000000000..ac43b10ec85
--- /dev/null
+++ b/src/test/rustdoc/deref-recursive.rs
@@ -0,0 +1,40 @@
+// #26207: Show all methods reachable via Deref impls, recursing through multiple dereferencing
+// levels if needed.
+
+// @has 'foo/struct.Foo.html'
+// @has '-' '//*[@id="deref-methods-Bar"]' 'Methods from Deref<Target = Bar>'
+// @has '-' '//*[@class="impl-items"]//*[@id="method.bar"]' 'pub fn bar(&self)'
+// @has '-' '//*[@id="deref-methods-Baz"]' 'Methods from Deref<Target = Baz>'
+// @has '-' '//*[@class="impl-items"]//*[@id="method.baz"]' 'pub fn baz(&self)'
+// @has '-' '//*[@class="sidebar-title"]/a[@href="#deref-methods-Bar"]' 'Methods from Deref<Target=Bar>'
+// @has '-' '//*[@class="sidebar-links"]/a[@href="#method.bar"]' 'bar'
+// @has '-' '//*[@class="sidebar-title"]/a[@href="#deref-methods-Baz"]' 'Methods from Deref<Target=Baz>'
+// @has '-' '//*[@class="sidebar-links"]/a[@href="#method.baz"]' 'baz'
+
+#![crate_name = "foo"]
+
+use std::ops::Deref;
+
+pub struct Foo(Bar);
+pub struct Bar(Baz);
+pub struct Baz;
+
+impl Deref for Foo {
+    type Target = Bar;
+    fn deref(&self) -> &Bar { &self.0 }
+}
+
+impl Deref for Bar {
+    type Target = Baz;
+    fn deref(&self) -> &Baz { &self.0 }
+}
+
+impl Bar {
+    /// This appears under `Foo` methods
+    pub fn bar(&self) {}
+}
+
+impl Baz {
+    /// This should also appear in `Foo` methods when recursing
+    pub fn baz(&self) {}
+}
diff --git a/src/test/rustdoc/deref-typedef.rs b/src/test/rustdoc/deref-typedef.rs
index d42ff384b29..ad7a96c5dad 100644
--- a/src/test/rustdoc/deref-typedef.rs
+++ b/src/test/rustdoc/deref-typedef.rs
@@ -1,12 +1,12 @@
 #![crate_name = "foo"]
 
 // @has 'foo/struct.Bar.html'
-// @has '-' '//*[@id="deref-methods"]' 'Methods from Deref<Target = FooJ>'
+// @has '-' '//*[@id="deref-methods-FooJ"]' 'Methods from Deref<Target = FooJ>'
 // @has '-' '//*[@class="impl-items"]//*[@id="method.foo_a"]' 'pub fn foo_a(&self)'
 // @has '-' '//*[@class="impl-items"]//*[@id="method.foo_b"]' 'pub fn foo_b(&self)'
 // @has '-' '//*[@class="impl-items"]//*[@id="method.foo_c"]' 'pub fn foo_c(&self)'
 // @has '-' '//*[@class="impl-items"]//*[@id="method.foo_j"]' 'pub fn foo_j(&self)'
-// @has '-' '//*[@class="sidebar-title"]/a[@href="#deref-methods"]' 'Methods from Deref<Target=FooJ>'
+// @has '-' '//*[@class="sidebar-title"]/a[@href="#deref-methods-FooJ"]' 'Methods from Deref<Target=FooJ>'
 // @has '-' '//*[@class="sidebar-links"]/a[@href="#method.foo_a"]' 'foo_a'
 // @has '-' '//*[@class="sidebar-links"]/a[@href="#method.foo_b"]' 'foo_b'
 // @has '-' '//*[@class="sidebar-links"]/a[@href="#method.foo_c"]' 'foo_c'
diff --git a/src/test/rustdoc/recursive-deref-sidebar.rs b/src/test/rustdoc/recursive-deref-sidebar.rs
index fcb636ade8f..65a7debc253 100644
--- a/src/test/rustdoc/recursive-deref-sidebar.rs
+++ b/src/test/rustdoc/recursive-deref-sidebar.rs
@@ -15,7 +15,7 @@ impl Deref for A {
     fn deref(&self) -> &B { todo!() }
 }
 
-// @!has recursive_deref_sidebar/struct.A.html '//div[@class="sidebar-links"]' 'foo_c'
+// @has recursive_deref_sidebar/struct.A.html '//div[@class="sidebar-links"]' 'foo_c'
 impl Deref for B {
     type Target = C;
     fn deref(&self) -> &C { todo!() }
diff --git a/src/test/rustdoc/recursive-deref.rs b/src/test/rustdoc/recursive-deref.rs
index 3d17bce4721..18634e1b360 100644
--- a/src/test/rustdoc/recursive-deref.rs
+++ b/src/test/rustdoc/recursive-deref.rs
@@ -1,7 +1,9 @@
 use std::ops::Deref;
 
+// Cyclic deref with the parent (which is not the top parent).
 pub struct A;
 pub struct B;
+pub struct C;
 
 // @has recursive_deref/struct.A.html '//h3[@class="code-header in-band"]' 'impl Deref for A'
 impl Deref for A {
@@ -14,7 +16,80 @@ impl Deref for A {
 
 // @has recursive_deref/struct.B.html '//h3[@class="code-header in-band"]' 'impl Deref for B'
 impl Deref for B {
-    type Target = A;
+    type Target = C;
+
+    fn deref(&self) -> &Self::Target {
+        panic!()
+    }
+}
+
+// @has recursive_deref/struct.C.html '//h3[@class="code-header in-band"]' 'impl Deref for C'
+impl Deref for C {
+    type Target = B;
+
+    fn deref(&self) -> &Self::Target {
+        panic!()
+    }
+}
+
+// Cyclic deref with the grand-parent (which is not the top parent).
+pub struct D;
+pub struct E;
+pub struct F;
+pub struct G;
+
+// @has recursive_deref/struct.D.html '//h3[@class="code-header in-band"]' 'impl Deref for D'
+impl Deref for D {
+    type Target = E;
+
+    fn deref(&self) -> &Self::Target {
+        panic!()
+    }
+}
+
+// @has recursive_deref/struct.E.html '//h3[@class="code-header in-band"]' 'impl Deref for E'
+impl Deref for E {
+    type Target = F;
+
+    fn deref(&self) -> &Self::Target {
+        panic!()
+    }
+}
+
+// @has recursive_deref/struct.F.html '//h3[@class="code-header in-band"]' 'impl Deref for F'
+impl Deref for F {
+    type Target = G;
+
+    fn deref(&self) -> &Self::Target {
+        panic!()
+    }
+}
+
+// @has recursive_deref/struct.G.html '//h3[@class="code-header in-band"]' 'impl Deref for G'
+impl Deref for G {
+    type Target = E;
+
+    fn deref(&self) -> &Self::Target {
+        panic!()
+    }
+}
+
+// Cyclic deref with top parent.
+pub struct H;
+pub struct I;
+
+// @has recursive_deref/struct.H.html '//h3[@class="code-header in-band"]' 'impl Deref for H'
+impl Deref for H {
+    type Target = I;
+
+    fn deref(&self) -> &Self::Target {
+        panic!()
+    }
+}
+
+// @has recursive_deref/struct.I.html '//h3[@class="code-header in-band"]' 'impl Deref for I'
+impl Deref for I {
+    type Target = H;
 
     fn deref(&self) -> &Self::Target {
         panic!()