Auto merge of #97842 - notriddle:notriddle/tuple-docs, r=jsha,GuillaumeGomez

Improve the tuple and unit trait docs

* Reduce duplicate impls; show only the `(T,)` and include a sentence saying that there exists ones up to twelve of them.
* Show `Copy` and `Clone`.
* Show auto traits like `Send` and `Sync`, and blanket impls like `Any`.

Here's the new version:

* <https://notriddle.com/notriddle-rustdoc-test/std/primitive.tuple.html>
* <https://notriddle.com/notriddle-rustdoc-test/std/primitive.unit.html>

3 files changed, 54 insertions, 0 deletions

diff --git a/src/test/rustdoc/primitive-tuple-auto-trait.rs b/src/test/rustdoc/primitive-tuple-auto-trait.rs
new file mode 100644
index 00000000000..71b0b077009
--- /dev/null
+++ b/src/test/rustdoc/primitive-tuple-auto-trait.rs
@@ -0,0 +1,22 @@
+// compile-flags: --crate-type lib --edition 2018
+
+#![crate_name = "foo"]
+#![feature(rustdoc_internals)]
+
+// @has foo/primitive.tuple.html '//a[@class="primitive"]' 'tuple'
+// @has - '//span[@class="in-band"]' 'Primitive Type tuple'
+// @has - '//section[@id="main-content"]//div[@class="docblock"]//p' 'this is a test!'
+// @has - '//h2[@id="synthetic-implementations"]' 'Auto Trait Implementations'
+// @has - '//div[@id="synthetic-implementations-list"]//h3' 'Send'
+// @has - '//div[@id="synthetic-implementations-list"]//h3' 'Sync'
+#[doc(primitive = "tuple")]
+/// this is a test!
+///
+// Hardcoded anchor to header written in library/core/src/primitive_docs.rs
+// @has - '//h2[@id="trait-implementations-1"]' 'Trait implementations'
+/// # Trait implementations
+///
+/// This header is hard-coded in the HTML format linking for `#[doc(tuple_variadics)]`.
+/// To make sure it gets linked correctly, we need to make sure the hardcoded anchor
+/// in the code matches what rustdoc generates for the header.
+mod tuple_prim {}
diff --git a/src/test/rustdoc/primitive-tuple-variadic.rs b/src/test/rustdoc/primitive-tuple-variadic.rs
new file mode 100644
index 00000000000..4fd6254f674
--- /dev/null
+++ b/src/test/rustdoc/primitive-tuple-variadic.rs
@@ -0,0 +1,18 @@
+// compile-flags: --crate-type lib --edition 2018
+
+#![crate_name = "foo"]
+#![feature(rustdoc_internals)]
+
+pub trait Foo {}
+
+// @has foo/trait.Foo.html
+// @has - '//section[@id="impl-Foo-for-(T%2C)"]/h3' 'impl<T> Foo for (T₁, T₂, …, Tₙ)'
+#[doc(tuple_variadic)]
+impl<T> Foo for (T,) {}
+
+pub trait Bar {}
+
+// @has foo/trait.Bar.html
+// @has - '//section[@id="impl-Bar-for-(U%2C)"]/h3' 'impl<U: Foo> Bar for (U₁, U₂, …, Uₙ)'
+#[doc(tuple_variadic)]
+impl<U: Foo> Bar for (U,) {}
diff --git a/src/test/rustdoc/primitive-unit-auto-trait.rs b/src/test/rustdoc/primitive-unit-auto-trait.rs
new file mode 100644
index 00000000000..76182622ef5
--- /dev/null
+++ b/src/test/rustdoc/primitive-unit-auto-trait.rs
@@ -0,0 +1,14 @@
+// compile-flags: --crate-type lib --edition 2018
+
+#![crate_name = "foo"]
+#![feature(rustdoc_internals)]
+
+// @has foo/primitive.unit.html '//a[@class="primitive"]' 'unit'
+// @has - '//span[@class="in-band"]' 'Primitive Type unit'
+// @has - '//section[@id="main-content"]//div[@class="docblock"]//p' 'this is a test!'
+// @has - '//h2[@id="synthetic-implementations"]' 'Auto Trait Implementations'
+// @has - '//div[@id="synthetic-implementations-list"]//h3' 'impl Send for ()'
+// @has - '//div[@id="synthetic-implementations-list"]//h3' 'impl Sync for ()'
+#[doc(primitive = "unit")]
+/// this is a test!
+mod unit_prim {}