Add modifiers to highlighting for extern crate

Author: asuto15

src/tools/rust-analyzer/crates/ide/src/syntax_highlighting/highlight.rs

@@ -703,7 +703,24 @@ fn highlight_name_ref_by_syntax(
     };
 
     match parent.kind() {
-        EXTERN_CRATE => HlTag::Symbol(SymbolKind::Module).into(),
+        EXTERN_CRATE => {
+            let mut h: Highlight = HlTag::Symbol(SymbolKind::Module).into();
+            let is_crate_root = if let Some(extern_crate) = ast::ExternCrate::cast(parent.clone()) {
+                if let Some(first_segment) = extern_crate.name_ref() {
+                    first_segment.syntax().text() == name.syntax().text()
+                } else {
+                    false
+                }
+            } else {
+                false
+            };
+
+            if is_crate_root {
+                h |= HlMod::CrateRoot;
+            }
+
+            h | HlMod::Library
+        },
         METHOD_CALL_EXPR => ast::MethodCallExpr::cast(parent)
             .and_then(|it| highlight_method_call(sema, krate, &it, edition))
             .unwrap_or_else(|| SymbolKind::Method.into()),

src/tools/rust-analyzer/crates/ide/src/syntax_highlighting/test_data/highlight_doctest.html

@@ -51,7 +51,13 @@
 <span class="comment documentation">//! ```</span>
 
 <span class="comment documentation">//! ```rust</span>
-<span class="comment documentation">//!</span><span class="comment documentation"> </span><span class="keyword injected">extern</span><span class="none injected"> </span><span class="keyword injected">crate</span><span class="none injected"> </span><span class="module injected">Krate</span><span class="semicolon injected">;</span>
+<span class="comment documentation">//!</span><span class="comment documentation"> </span><span class="keyword injected">extern</span><span class="none injected"> </span><span class="keyword injected">crate</span><span class="none injected"> </span><span class="self_keyword crate_root injected">self</span><span class="semicolon injected">;</span>
+<span class="comment documentation">//!</span><span class="comment documentation"> </span><span class="keyword injected">extern</span><span class="none injected"> </span><span class="keyword injected">crate</span><span class="none injected"> </span><span class="module crate_root injected library">std</span><span class="semicolon injected">;</span>
+<span class="comment documentation">//!</span><span class="comment documentation"> </span><span class="keyword injected">extern</span><span class="none injected"> </span><span class="keyword injected">crate</span><span class="none injected"> </span><span class="module crate_root injected library">core</span><span class="semicolon injected">;</span>
+<span class="comment documentation">//!</span><span class="comment documentation"> </span><span class="keyword injected">extern</span><span class="none injected"> </span><span class="keyword injected">crate</span><span class="none injected"> </span><span class="module crate_root injected library">alloc</span><span class="semicolon injected">;</span>
+<span class="comment documentation">//!</span><span class="comment documentation"> </span><span class="keyword injected">extern</span><span class="none injected"> </span><span class="keyword injected">crate</span><span class="none injected"> </span><span class="module crate_root injected library">proc_macro</span><span class="semicolon injected">;</span>
+<span class="comment documentation">//!</span><span class="comment documentation"> </span><span class="keyword injected">extern</span><span class="none injected"> </span><span class="keyword injected">crate</span><span class="none injected"> </span><span class="module crate_root injected library">test</span><span class="semicolon injected">;</span>
+<span class="comment documentation">//!</span><span class="comment documentation"> </span><span class="keyword injected">extern</span><span class="none injected"> </span><span class="keyword injected">crate</span><span class="none injected"> </span><span class="module crate_root injected library">Krate</span><span class="semicolon injected">;</span>
 <span class="comment documentation">//! ```</span>
 <span class="keyword">mod</span> <span class="module declaration">outline_module</span><span class="semicolon">;</span>
 

src/tools/rust-analyzer/crates/ide/src/syntax_highlighting/tests.rs

@@ -723,6 +723,12 @@ fn test_highlight_doc_comment() {
 //! ```
 
 //! ```rust
+//! extern crate self;
+//! extern crate std;
+//! extern crate core;
+//! extern crate alloc;
+//! extern crate proc_macro;
+//! extern crate test;
 //! extern crate Krate;
 //! ```
 mod outline_module;