Rollup merge of #142472 - GuillaumeGomez:doc-attribute-attribute, r=fmease

Add new `doc(attribute = "...")` attribute

Fixes rust-lang/rust#141123.

The implementation and purpose of this new `#[doc(attribute = "...")]` attribute is very close to `#[doc(keyword = "...")]`. Which means that luckily for us, most of the code needed was already in place and `@Noratrieb` nicely wrote a first draft that helped me implement this new attribute very fast.

Now with all this said, there is one thing I didn't do yet: adding a `rustdoc-js-std` test. I added GUI tests with search results for attributes so should be fine but I still plan on adding one for it once documentation for builtin attributes will be written into the core/std libs.

You can test it [here](https://rustdoc.crud.net/imperio/doc-attribute-attribute/foo/index.html).

cc `@Noratrieb` `@Veykril`

2 files changed, 4 insertions, 4 deletions

diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index 679e663f886..d4f7fb276a9 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/compiler/rustc_resolve/src/late.rs
@@ -5016,7 +5016,7 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
             }
             ResolveDocLinks::Exported
                 if !maybe_exported.eval(self.r)
-                    && !rustdoc::has_primitive_or_keyword_docs(attrs) =>
+                    && !rustdoc::has_primitive_or_keyword_or_attribute_docs(attrs) =>
             {
                 return;
             }
diff --git a/compiler/rustc_resolve/src/rustdoc.rs b/compiler/rustc_resolve/src/rustdoc.rs
index f9f2f84bc50..804792c6f28 100644
--- a/compiler/rustc_resolve/src/rustdoc.rs
+++ b/compiler/rustc_resolve/src/rustdoc.rs
@@ -373,8 +373,8 @@ pub fn inner_docs(attrs: &[impl AttributeExt]) -> bool {
     true
 }
 
-/// Has `#[rustc_doc_primitive]` or `#[doc(keyword)]`.
-pub fn has_primitive_or_keyword_docs(attrs: &[impl AttributeExt]) -> bool {
+/// Has `#[rustc_doc_primitive]` or `#[doc(keyword)]` or `#[doc(attribute)]`.
+pub fn has_primitive_or_keyword_or_attribute_docs(attrs: &[impl AttributeExt]) -> bool {
     for attr in attrs {
         if attr.has_name(sym::rustc_doc_primitive) {
             return true;
@@ -382,7 +382,7 @@ pub fn has_primitive_or_keyword_docs(attrs: &[impl AttributeExt]) -> bool {
             && let Some(items) = attr.meta_item_list()
         {
             for item in items {
-                if item.has_name(sym::keyword) {
+                if item.has_name(sym::keyword) || item.has_name(sym::attribute) {
                     return true;
                 }
             }