Add regression test for rust-lang#140739

Author: GuillaumeGomez

tests/rustdoc/type-alias/repr.rs

@@ -0,0 +1,42 @@
+// This test ensures that the `repr` attribute is displayed in type aliases.
+//
+// Regression test for <https://github.com/rust-lang/rust/issues/140739>.
+
+#![crate_name = "foo"]
+
+/// bla
+#[repr(C)]
+pub struct Foo1;
+
+//@ has 'foo/type.Bar1.html'
+//@ has - '//*[@class="rust item-decl"]/code' '#[repr(C)]pub struct Bar1;'
+// Ensures that we see the doc comment of the type alias and not of the aliased type.
+//@ has - '//*[@class="toggle top-doc"]/*[@class="docblock"]' 'bar'
+/// bar
+pub type Bar1 = Foo1;
+
+/// bla
+#[repr(C)]
+pub union Foo2 {
+    pub a: u8,
+}
+
+//@ has 'foo/type.Bar2.html'
+//@ matches - '//*[@class="rust item-decl"]' '#\[repr\(C\)\]\npub union Bar2 \{*'
+// Ensures that we see the doc comment of the type alias and not of the aliased type.
+//@ has - '//*[@class="toggle top-doc"]/*[@class="docblock"]' 'bar'
+/// bar
+pub type Bar2 = Foo2;
+
+/// bla
+#[repr(C)]
+pub enum Foo3 {
+    A,
+}
+
+//@ has 'foo/type.Bar3.html'
+//@ matches - '//*[@class="rust item-decl"]' '#\[repr\(C\)\]pub enum Bar3 \{*'
+// Ensures that we see the doc comment of the type alias and not of the aliased type.
+//@ has - '//*[@class="toggle top-doc"]/*[@class="docblock"]' 'bar'
+/// bar
+pub type Bar3 = Foo3;