Auto merge of #84283 - jsha:de-emphasize-attributes, r=GuillaumeGomez

rustdoc: Reduce visual weight of attributes.

Followup from #83337. As part of that PR, we stopped hiding attributes behind a toggle, because most things have just zero or one attributes. However, this made clear that the current rendering of attributes emphasizes them a lot, which distracts from function signatures. This PR changes their color of attributes to be the same as the toggles, and reduces their font weight.

This also removes `#[lang]` from the list of ALLOWED_ATTRIBUTES. This attribute is an implementation detail rather than part of the public-facing documentation.

![image](https://user-images.githubusercontent.com/220205/115131061-cc407d80-9fa9-11eb-9a77-ad3f3217f391.png)

Demo at https://hoffman-andrews.com/rust/de-emph-attr/std/string/struct.String.html#method.trim

5 files changed, 10 insertions, 4 deletions

diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index 8b5e1aa1817..7cb6466817c 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -986,7 +986,6 @@ fn render_assoc_item(
 
 const ALLOWED_ATTRIBUTES: &[Symbol] = &[
     sym::export_name,
-    sym::lang,
     sym::link_section,
     sym::must_use,
     sym::no_mangle,
diff --git a/src/librustdoc/html/static/rustdoc.css b/src/librustdoc/html/static/rustdoc.css
index 427564cd779..570dabbd361 100644
--- a/src/librustdoc/html/static/rustdoc.css
+++ b/src/librustdoc/html/static/rustdoc.css
@@ -967,6 +967,10 @@ a.test-arrow:hover{
 	color: inherit;
 }
 
+.code-attribute {
+	font-weight: 300;
+}
+
 .collapse-toggle {
 	font-weight: 300;
 	position: absolute;
diff --git a/src/librustdoc/html/static/themes/ayu.css b/src/librustdoc/html/static/themes/ayu.css
index 5f6f3d66e57..b0a8c41fb08 100644
--- a/src/librustdoc/html/static/themes/ayu.css
+++ b/src/librustdoc/html/static/themes/ayu.css
@@ -329,7 +329,8 @@ a.test-arrow:hover {
 	color: #c5c5c5;
 }
 
-.toggle-label {
+.toggle-label,
+.code-attribute {
 	color: #999;
 }
 
diff --git a/src/librustdoc/html/static/themes/dark.css b/src/librustdoc/html/static/themes/dark.css
index 2ce6cf4cc45..b702dc4a937 100644
--- a/src/librustdoc/html/static/themes/dark.css
+++ b/src/librustdoc/html/static/themes/dark.css
@@ -274,7 +274,8 @@ a.test-arrow:hover{
 	background-color: #4e8bca;
 }
 
-.toggle-label {
+.toggle-label,
+.code-attribute {
 	color: #999;
 }
 
diff --git a/src/librustdoc/html/static/themes/light.css b/src/librustdoc/html/static/themes/light.css
index 31b3562cfcb..566ed62a628 100644
--- a/src/librustdoc/html/static/themes/light.css
+++ b/src/librustdoc/html/static/themes/light.css
@@ -267,7 +267,8 @@ a.test-arrow:hover{
 	background-color: #4e8bca;
 }
 
-.toggle-label {
+.toggle-label,
+.code-attribute {
 	color: #999;
 }