On second thought, we want to preserve the textMate here where all punctuation that are from a Attr be highlited as Attribute

Author: GrayJack

crates/ra_ide/src/syntax_highlighting.rs

@@ -540,7 +540,6 @@ fn highlight_element(
             }
         }
         p if p.is_punct() => match p {
-            T![#] => HighlightTag::Attribute.into(),
             T![::] | T![->] | T![=>] | T![&] | T![..] | T![=] | T![@] => {
                 HighlightTag::Operator.into()
             }
@@ -581,6 +580,9 @@ fn highlight_element(
             _ if element.parent().and_then(ast::DotDotPat::cast).is_some() => {
                 HighlightTag::Operator.into()
             }
+            _ if element.parent().and_then(ast::Attr::cast).is_some() => {
+                HighlightTag::Attribute.into()
+            }
             _ => HighlightTag::Punctuation.into(),
         },
 

crates/ra_ide/test_data/highlight_doctest.html

@@ -50,7 +50,7 @@
     <span class="comment documentation">/// # Examples</span>
     <span class="comment documentation">///</span>
     <span class="comment documentation">/// ```</span>
-    <span class="comment documentation">/// #</span><span class="generic injected"> </span><span class="attribute injected">#</span><span class="punctuation injected">!</span><span class="punctuation injected">[</span><span class="function attribute injected">allow</span><span class="punctuation injected">(</span><span class="attribute injected">unused_mut</span><span class="punctuation injected">)</span><span class="punctuation injected">]</span>
+    <span class="comment documentation">/// #</span><span class="generic injected"> </span><span class="attribute injected">#</span><span class="attribute injected">!</span><span class="attribute injected">[</span><span class="function attribute injected">allow</span><span class="punctuation injected">(</span><span class="attribute injected">unused_mut</span><span class="punctuation injected">)</span><span class="attribute injected">]</span>
     <span class="comment documentation">/// </span><span class="keyword injected">let</span><span class="generic injected"> </span><span class="keyword injected">mut</span><span class="generic injected"> </span><span class="variable declaration injected mutable">foo</span><span class="punctuation injected">:</span><span class="generic injected"> </span><span class="struct injected">Foo</span><span class="generic injected"> </span><span class="operator injected">=</span><span class="generic injected"> </span><span class="struct injected">Foo</span><span class="operator injected">::</span><span class="function injected">new</span><span class="punctuation injected">(</span><span class="punctuation injected">)</span><span class="punctuation injected">;</span><span class="punctuation injected">
 </span>    <span class="comment documentation">/// ```</span>
     <span class="keyword">pub</span> <span class="keyword">const</span> <span class="keyword">fn</span> <span class="function declaration">new</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="struct">Foo</span> <span class="punctuation">{</span>

crates/ra_ide/test_data/highlighting.html

@@ -35,7 +35,7 @@
 
 .unresolved_reference { color: #FC5555; text-decoration: wavy underline; }
 </style>
-<pre><code><span class="attribute">#</span><span class="punctuation">[</span><span class="function attribute">derive</span><span class="punctuation">(</span><span class="attribute">Clone</span><span class="punctuation">,</span><span class="attribute"> Debug</span><span class="punctuation">)</span><span class="punctuation">]</span>
+<pre><code><span class="attribute">#</span><span class="attribute">[</span><span class="function attribute">derive</span><span class="punctuation">(</span><span class="attribute">Clone</span><span class="punctuation">,</span><span class="attribute"> Debug</span><span class="punctuation">)</span><span class="attribute">]</span>
 <span class="keyword">struct</span> <span class="struct declaration">Foo</span> <span class="punctuation">{</span>
     <span class="keyword">pub</span> <span class="field declaration">x</span><span class="punctuation">:</span> <span class="builtin_type">i32</span><span class="punctuation">,</span>
     <span class="keyword">pub</span> <span class="field declaration">y</span><span class="punctuation">:</span> <span class="builtin_type">i32</span><span class="punctuation">,</span>