Rollup merge of #73101 - jyn514:rustdoc-absolute-module, r=Manishearth

Resolve items for cross-crate imports relative to the original module

~~Blocked on https://github.com/rust-lang/rust/pull/73103 and https://github.com/rust-lang/rust/pull/73566~~

Closes https://github.com/rust-lang/rust/issues/65983.

I tested on the following code (as mentioned in https://github.com/rust-lang/rust/issues/65983#issuecomment-640250993):

```
pub use rand::Rng;
```
and rustdoc generated the following link: https://rust-random.github.io/rand/rand_core/trait.RngCore.html

17 files changed, 173 insertions, 2 deletions

diff --git a/src/test/rustdoc-ui/intra-links-private.rs b/src/test/rustdoc-ui/intra-links-private.rs
index b7906aba5b1..86cf9fed3da 100644
--- a/src/test/rustdoc-ui/intra-links-private.rs
+++ b/src/test/rustdoc-ui/intra-links-private.rs
@@ -1,7 +1,7 @@
 // check-pass
 // revisions: public private
 // [private]compile-flags: --document-private-items
-#![cfg_attr(private, deny(intra_doc_resolution_failure))]
+#![cfg_attr(private, deny(intra_doc_link_resolution_failure))]
 
 /// docs [DontDocMe]
 //[public]~^ WARNING `[DontDocMe]` public documentation for `DocMe` links to a private item
diff --git a/src/test/rustdoc/intra-doc-crate/additional_doc.rs b/src/test/rustdoc/intra-doc-crate/additional_doc.rs
new file mode 100644
index 00000000000..adfa7f5754e
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/additional_doc.rs
@@ -0,0 +1,10 @@
+// aux-build:additional_doc.rs
+// build-aux-docs
+#![deny(intra_doc_link_resolution_failure)]
+
+extern crate my_rand;
+
+// @has 'additional_doc/trait.Rng.html' '//a[@href="../additional_doc/trait.Rng.html"]' 'Rng'
+// @has 'additional_doc/trait.Rng.html' '//a[@href="../my_rand/trait.RngCore.html"]' 'RngCore'
+/// This is an [`Rng`].
+pub use my_rand::Rng;
diff --git a/src/test/rustdoc/intra-doc-crate/auxiliary/additional_doc.rs b/src/test/rustdoc/intra-doc-crate/auxiliary/additional_doc.rs
new file mode 100644
index 00000000000..8b8793e75ed
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/auxiliary/additional_doc.rs
@@ -0,0 +1,6 @@
+#![crate_name = "my_rand"]
+#![deny(intra_doc_link_resolution_failure)]
+
+pub trait RngCore {}
+/// Rng extends [`RngCore`].
+pub trait Rng: RngCore {}
diff --git a/src/test/rustdoc/intra-doc-crate/auxiliary/intra-doc-basic.rs b/src/test/rustdoc/intra-doc-crate/auxiliary/intra-doc-basic.rs
new file mode 100644
index 00000000000..2ee5835a7df
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/auxiliary/intra-doc-basic.rs
@@ -0,0 +1,7 @@
+#![crate_name = "a"]
+#![deny(intra_doc_link_resolution_failure)]
+
+pub struct Foo;
+
+/// Link to [Foo]
+pub struct Bar;
diff --git a/src/test/rustdoc/intra-doc-crate/auxiliary/macro_inner.rs b/src/test/rustdoc/intra-doc-crate/auxiliary/macro_inner.rs
new file mode 100644
index 00000000000..abd41fec130
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/auxiliary/macro_inner.rs
@@ -0,0 +1,10 @@
+#![crate_name = "macro_inner"]
+#![deny(intra_doc_link_resolution_failure)]
+
+pub struct Foo;
+
+/// See also [`Foo`]
+#[macro_export]
+macro_rules! my_macro {
+    () => {}
+}
diff --git a/src/test/rustdoc/intra-doc-crate/auxiliary/module.rs b/src/test/rustdoc/intra-doc-crate/auxiliary/module.rs
new file mode 100644
index 00000000000..5d63d7e37b6
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/auxiliary/module.rs
@@ -0,0 +1,7 @@
+#![crate_name = "module_inner"]
+#![deny(intra_doc_link_resolution_failure)]
+/// [SomeType] links to [bar]
+pub struct SomeType;
+pub trait SomeTrait {}
+/// [bar] links to [SomeTrait] and also [SomeType]
+pub mod bar {}
diff --git a/src/test/rustdoc/intra-doc-crate/auxiliary/proc_macro.rs b/src/test/rustdoc/intra-doc-crate/auxiliary/proc_macro.rs
new file mode 100644
index 00000000000..0d5a954075d
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/auxiliary/proc_macro.rs
@@ -0,0 +1,20 @@
+// force-host
+// no-prefer-dynamic
+// compile-flags: --crate-type proc-macro
+#![crate_type="proc-macro"]
+#![crate_name="proc_macro_inner"]
+
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+
+/// Links to [`OtherDerive`]
+#[proc_macro_derive(DeriveA)]
+pub fn a_derive(input: TokenStream) -> TokenStream {
+    input
+}
+
+#[proc_macro_derive(OtherDerive)]
+pub fn other_derive(input: TokenStream) -> TokenStream {
+    input
+}
diff --git a/src/test/rustdoc/intra-doc-crate/auxiliary/submodule-inner.rs b/src/test/rustdoc/intra-doc-crate/auxiliary/submodule-inner.rs
new file mode 100644
index 00000000000..3a22d13e673
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/auxiliary/submodule-inner.rs
@@ -0,0 +1,12 @@
+#![crate_name = "a"]
+#![deny(intra_doc_link_resolution_failure)]
+
+pub mod bar {
+   pub struct Bar;
+}
+
+pub mod foo {
+  use crate::bar;
+  /// link to [bar::Bar]
+  pub struct Foo;
+}
diff --git a/src/test/rustdoc/intra-doc-crate/auxiliary/submodule-outer.rs b/src/test/rustdoc/intra-doc-crate/auxiliary/submodule-outer.rs
new file mode 100644
index 00000000000..b8ca4e44e1f
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/auxiliary/submodule-outer.rs
@@ -0,0 +1,13 @@
+#![crate_name = "bar"]
+#![deny(intra_doc_link_resolution_failure)]
+
+pub trait Foo {
+    /// [`Bar`] [`Baz`]
+    fn foo();
+}
+
+pub trait Bar {
+}
+
+pub trait Baz {
+}
diff --git a/src/test/rustdoc/intra-doc-crate/auxiliary/traits.rs b/src/test/rustdoc/intra-doc-crate/auxiliary/traits.rs
new file mode 100644
index 00000000000..c16e39d56f3
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/auxiliary/traits.rs
@@ -0,0 +1,16 @@
+#![crate_name = "inner"]
+/// this is a trait
+pub trait SomeTrait {
+    /// this is a method for [a trait][SomeTrait]
+    fn foo();
+}
+
+pub mod bar {
+    use super::SomeTrait;
+
+    pub struct BarStruct;
+
+    impl SomeTrait for BarStruct {
+        fn foo() {}
+    }
+}
diff --git a/src/test/rustdoc/intra-doc-crate/basic.rs b/src/test/rustdoc/intra-doc-crate/basic.rs
new file mode 100644
index 00000000000..a245a0f8453
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/basic.rs
@@ -0,0 +1,9 @@
+// aux-build:intra-doc-basic.rs
+// build-aux-docs
+#![deny(intra_doc_link_resolution_failure)]
+
+// from https://github.com/rust-lang/rust/issues/65983
+extern crate a;
+
+// @has 'basic/struct.Bar.html' '//a[@href="../a/struct.Foo.html"]' 'Foo'
+pub use a::Bar;
diff --git a/src/test/rustdoc/intra-doc-crate/macro.rs b/src/test/rustdoc/intra-doc-crate/macro.rs
new file mode 100644
index 00000000000..72fd57b6b0c
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/macro.rs
@@ -0,0 +1,12 @@
+// ignore-tidy-linelength
+// aux-build:macro_inner.rs
+// aux-build:proc_macro.rs
+// build-aux-docs
+#![deny(intra_doc_link_resolution_failure)]
+extern crate macro_inner;
+extern crate proc_macro_inner;
+
+// @has 'macro/macro.my_macro.html' '//a[@href="../macro_inner/struct.Foo.html"]' 'Foo'
+pub use macro_inner::my_macro;
+// @has 'macro/derive.DeriveA.html' '//a[@href="../proc_macro_inner/derive.OtherDerive.html"]' 'OtherDerive'
+pub use proc_macro_inner::DeriveA;
diff --git a/src/test/rustdoc/intra-doc-crate/module.rs b/src/test/rustdoc/intra-doc-crate/module.rs
new file mode 100644
index 00000000000..67fa7293f37
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/module.rs
@@ -0,0 +1,8 @@
+// outer.rs
+// aux-build: module.rs
+// build-aux-docs
+#![deny(intra_doc_link_resolution_failure)]
+extern crate module_inner;
+// @has 'module/bar/index.html' '//a[@href="../../module_inner/trait.SomeTrait.html"]' 'SomeTrait'
+// @has 'module/bar/index.html' '//a[@href="../../module_inner/struct.SomeType.html"]' 'SomeType'
+pub use module_inner::bar;
diff --git a/src/test/rustdoc/intra-doc-crate/submodule-inner.rs b/src/test/rustdoc/intra-doc-crate/submodule-inner.rs
new file mode 100644
index 00000000000..b4b615bf9ed
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/submodule-inner.rs
@@ -0,0 +1,8 @@
+// aux-build:submodule-inner.rs
+// build-aux-docs
+#![deny(intra_doc_link_resolution_failure)]
+
+extern crate a;
+
+// @has 'submodule_inner/struct.Foo.html' '//a[@href="../a/bar/struct.Bar.html"]' 'Bar'
+pub use a::foo::Foo;
diff --git a/src/test/rustdoc/intra-doc-crate/submodule-outer.rs b/src/test/rustdoc/intra-doc-crate/submodule-outer.rs
new file mode 100644
index 00000000000..6b30ef8b3de
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/submodule-outer.rs
@@ -0,0 +1,16 @@
+// aux-build:submodule-outer.rs
+// edition:2018
+#![deny(intra_doc_link_resolution_failure)]
+
+extern crate bar as bar_;
+
+// from https://github.com/rust-lang/rust/issues/60883
+pub mod bar {
+    pub use ::bar_::Bar;
+}
+
+// NOTE: we re-exported both `Foo` and `Bar` here,
+// NOTE: so they are inlined and therefore we link to the current module.
+// @has 'submodule_outer/trait.Foo.html' '//a[@href="../submodule_outer/bar/trait.Bar.html"]' 'Bar'
+// @has 'submodule_outer/trait.Foo.html' '//a[@href="../submodule_outer/trait.Baz.html"]' 'Baz'
+pub use ::bar_::{Foo, Baz};
diff --git a/src/test/rustdoc/intra-doc-crate/traits.rs b/src/test/rustdoc/intra-doc-crate/traits.rs
new file mode 100644
index 00000000000..61733123690
--- /dev/null
+++ b/src/test/rustdoc/intra-doc-crate/traits.rs
@@ -0,0 +1,17 @@
+// ignore-test
+// ^ this is https://github.com/rust-lang/rust/issues/73829
+// aux-build:traits.rs
+// build-aux-docs
+// ignore-tidy-line-length
+#![deny(intra_doc_link_resolution_failure)]
+
+extern crate inner;
+use inner::SomeTrait;
+
+pub struct SomeStruct;
+
+ // @has 'traits/struct.SomeStruct.html' '//a[@href="../inner/trait.SomeTrait.html"]' 'SomeTrait'
+impl SomeTrait for SomeStruct {
+    // @has 'traits/struct.SomeStruct.html' '//a[@href="../inner/trait.SomeTrait.html"]' 'a trait'
+    fn foo() {}
+}
diff --git a/src/test/rustdoc/intra-link-prim-precedence.rs b/src/test/rustdoc/intra-link-prim-precedence.rs
index ca83d5e2281..d7ebb73b3be 100644
--- a/src/test/rustdoc/intra-link-prim-precedence.rs
+++ b/src/test/rustdoc/intra-link-prim-precedence.rs
@@ -1,5 +1,5 @@
 // ignore-tidy-linelength
-#![deny(intra_doc_resolution_failure)]
+#![deny(intra_doc_link_resolution_failure)]
 
 pub mod char {}