Rollup merge of #75237 - nbdd0121:rustdoc, r=jyn514

Display elided lifetime for non-reference type in doc

In edition 2018 we encourage writing `<'_>` explicitly, so rustdoc should display like such as well.

Fixes #75225

~~Somehow when I run the compiled rustdoc using `cargo +stage2 doc` on other crates, it correctly produces `<'_>`, but I couldn't get the std doc to do the same with `./x.py doc --stage 2`. Might this be related to the recent change to x.py about how the doc is built?~~

2 files changed, 54 insertions, 0 deletions

diff --git a/src/test/rustdoc/auxiliary/elided-lifetime.rs b/src/test/rustdoc/auxiliary/elided-lifetime.rs
new file mode 100644
index 00000000000..4f2c93379d8
--- /dev/null
+++ b/src/test/rustdoc/auxiliary/elided-lifetime.rs
@@ -0,0 +1,11 @@
+#![crate_name = "bar"]
+
+pub struct Ref<'a>(&'a u32);
+
+pub fn test5(a: &u32) -> Ref {
+    Ref(a)
+}
+
+pub fn test6(a: &u32) -> Ref<'_> {
+    Ref(a)
+}
diff --git a/src/test/rustdoc/elided-lifetime.rs b/src/test/rustdoc/elided-lifetime.rs
new file mode 100644
index 00000000000..5a32554f972
--- /dev/null
+++ b/src/test/rustdoc/elided-lifetime.rs
@@ -0,0 +1,43 @@
+// aux-build:elided-lifetime.rs
+//
+// rust-lang/rust#75225
+//
+// Since Rust 2018 we encourage writing out <'_> explicitly to make it clear
+// that borrowing is occuring. Make sure rustdoc is following the same idiom.
+
+#![crate_name = "foo"]
+
+pub struct Ref<'a>(&'a u32);
+type ARef<'a> = Ref<'a>;
+
+// @has foo/fn.test1.html
+// @matches - "Ref</a>&lt;'_&gt;"
+pub fn test1(a: &u32) -> Ref {
+    Ref(a)
+}
+
+// @has foo/fn.test2.html
+// @matches - "Ref</a>&lt;'_&gt;"
+pub fn test2(a: &u32) -> Ref<'_> {
+    Ref(a)
+}
+
+// @has foo/fn.test3.html
+// @matches - "Ref</a>&lt;'_&gt;"
+pub fn test3(a: &u32) -> ARef {
+    Ref(a)
+}
+
+// @has foo/fn.test4.html
+// @matches - "Ref</a>&lt;'_&gt;"
+pub fn test4(a: &u32) -> ARef<'_> {
+    Ref(a)
+}
+
+// Ensure external paths in inlined docs also display elided lifetime
+// @has foo/bar/fn.test5.html
+// @matches - "Ref</a>&lt;'_&gt;"
+// @has foo/bar/fn.test6.html
+// @matches - "Ref</a>&lt;'_&gt;"
+#[doc(inline)]
+pub extern crate bar;