4 files changed, 70 insertions, 28 deletions

diff --git a/crates/ide/src/diagnostics.rs b/crates/ide/src/diagnostics.rs
index 27d347dbd..dcac7c76d 100644
--- a/crates/ide/src/diagnostics.rs
+++ b/crates/ide/src/diagnostics.rs
@@ -299,10 +299,10 @@ fn unresolved_fix(id: &'static str, label: &str, target: TextRange) -> Assist {
 
 #[cfg(test)]
 mod tests {
-    use expect_test::{expect, Expect};
+    use expect_test::Expect;
     use ide_assists::AssistResolveStrategy;
     use stdx::trim_indent;
-    use test_utils::assert_eq_text;
+    use test_utils::{assert_eq_text, extract_annotations};
 
     use crate::{fixture, DiagnosticsConfig};
 
@@ -396,26 +396,51 @@ mod tests {
         expect.assert_debug_eq(&diagnostics)
     }
 
+    pub(crate) fn check_diagnostics(ra_fixture: &str) {
+        let (analysis, file_id) = fixture::file(ra_fixture);
+        let diagnostics = analysis
+            .diagnostics(&DiagnosticsConfig::default(), AssistResolveStrategy::All, file_id)
+            .unwrap();
+
+        let expected = extract_annotations(&*analysis.file_text(file_id).unwrap());
+        let actual = diagnostics.into_iter().map(|d| (d.range, d.message)).collect::<Vec<_>>();
+        assert_eq!(expected, actual);
+    }
+
     #[test]
     fn test_unresolved_macro_range() {
-        check_expect(
-            r#"foo::bar!(92);"#,
-            expect![[r#"
-                [
-                    Diagnostic {
-                        message: "unresolved macro `foo::bar!`",
-                        range: 5..8,
-                        severity: Error,
-                        fixes: None,
-                        unused: false,
-                        code: Some(
-                            DiagnosticCode(
-                                "unresolved-macro-call",
-                            ),
-                        ),
-                    },
-                ]
-            "#]],
+        check_diagnostics(
+            r#"
+foo::bar!(92);
+   //^^^ unresolved macro `foo::bar!`
+"#,
+        );
+    }
+
+    #[test]
+    fn unresolved_import_in_use_tree() {
+        // Only the relevant part of a nested `use` item should be highlighted.
+        check_diagnostics(
+            r#"
+use does_exist::{Exists, DoesntExist};
+                       //^^^^^^^^^^^ unresolved import
+
+use {does_not_exist::*, does_exist};
+   //^^^^^^^^^^^^^^^^^ unresolved import
+
+use does_not_exist::{
+    a,
+  //^ unresolved import
+    b,
+  //^ unresolved import
+    c,
+  //^ unresolved import
+};
+
+mod does_exist {
+    pub struct Exists;
+}
+"#,
         );
     }
 
diff --git a/crates/ide/src/syntax_highlighting/highlight.rs b/crates/ide/src/syntax_highlighting/highlight.rs
index b4a3d39c9..9503c936d 100644
--- a/crates/ide/src/syntax_highlighting/highlight.rs
+++ b/crates/ide/src/syntax_highlighting/highlight.rs
@@ -71,7 +71,7 @@ pub(super) fn element(
         }
         NAME_REF => {
             let name_ref = element.into_node().and_then(ast::NameRef::cast).unwrap();
-            highlight_func_by_name_ref(sema, &name_ref).unwrap_or_else(|| {
+            highlight_func_by_name_ref(sema, krate, &name_ref).unwrap_or_else(|| {
                 let is_self = name_ref.self_token().is_some();
                 let h = match NameRefClass::classify(sema, &name_ref) {
                     Some(name_kind) => match name_kind {
@@ -108,7 +108,7 @@ pub(super) fn element(
                         NameRefClass::FieldShorthand { .. } => SymbolKind::Field.into(),
                     },
                     None if syntactic_name_ref_highlighting => {
-                        highlight_name_ref_by_syntax(name_ref, sema)
+                        highlight_name_ref_by_syntax(name_ref, sema, krate)
                     }
                     None => HlTag::UnresolvedReference.into(),
                 };
@@ -434,19 +434,23 @@ fn highlight_def(db: &RootDatabase, krate: Option<hir::Crate>, def: Definition)
 
 fn highlight_func_by_name_ref(
     sema: &Semantics<RootDatabase>,
+    krate: Option<hir::Crate>,
     name_ref: &ast::NameRef,
 ) -> Option<Highlight> {
     let mc = name_ref.syntax().parent().and_then(ast::MethodCallExpr::cast)?;
-    highlight_method_call(sema, &mc)
+    highlight_method_call(sema, krate, &mc)
 }
 
 fn highlight_method_call(
     sema: &Semantics<RootDatabase>,
+    krate: Option<hir::Crate>,
     method_call: &ast::MethodCallExpr,
 ) -> Option<Highlight> {
     let func = sema.resolve_method_call(&method_call)?;
+
     let mut h = SymbolKind::Function.into();
     h |= HlMod::Associated;
+
     if func.is_unsafe(sema.db) || sema.is_unsafe_method_call(&method_call) {
         h |= HlMod::Unsafe;
     }
@@ -454,7 +458,10 @@ fn highlight_method_call(
         h |= HlMod::Async;
     }
     if func.as_assoc_item(sema.db).and_then(|it| it.containing_trait(sema.db)).is_some() {
-        h |= HlMod::Trait
+        h |= HlMod::Trait;
+    }
+    if Some(func.module(sema.db).krate()) != krate {
+        h |= HlMod::Library;
     }
 
     if let Some(self_param) = func.self_param(sema.db) {
@@ -503,7 +510,11 @@ fn highlight_name_by_syntax(name: ast::Name) -> Highlight {
     tag.into()
 }
 
-fn highlight_name_ref_by_syntax(name: ast::NameRef, sema: &Semantics<RootDatabase>) -> Highlight {
+fn highlight_name_ref_by_syntax(
+    name: ast::NameRef,
+    sema: &Semantics<RootDatabase>,
+    krate: Option<hir::Crate>,
+) -> Highlight {
     let default = HlTag::UnresolvedReference;
 
     let parent = match name.syntax().parent() {
@@ -514,7 +525,7 @@ fn highlight_name_ref_by_syntax(name: ast::NameRef, sema: &Semantics<RootDatabas
     match parent.kind() {
         METHOD_CALL_EXPR => {
             return ast::MethodCallExpr::cast(parent)
-                .and_then(|it| highlight_method_call(sema, &it))
+                .and_then(|it| highlight_method_call(sema, krate, &it))
                 .unwrap_or_else(|| SymbolKind::Function.into());
         }
         FIELD_EXPR => {
diff --git a/crates/ide/src/syntax_highlighting/test_data/highlighting.html b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
index 055d21109..0264e39a3 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlighting.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
@@ -258,7 +258,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 
     <span class="keyword">let</span> <span class="variable declaration">control_flow</span> <span class="operator">=</span> <span class="module library">foo</span><span class="operator">::</span><span class="function library">identity</span><span class="parenthesis">(</span><span class="module library">foo</span><span class="operator">::</span><span class="enum library">ControlFlow</span><span class="operator">::</span><span class="enum_variant library">Continue</span><span class="parenthesis">)</span><span class="semicolon">;</span>
 
-    <span class="keyword control">if</span> <span class="keyword">let</span> <span class="module library">foo</span><span class="operator">::</span><span class="enum library">ControlFlow</span><span class="operator">::</span><span class="enum_variant library">Die</span> <span class="operator">=</span> <span class="variable">control_flow</span> <span class="brace">{</span>
+    <span class="keyword control">if</span> <span class="variable">control_flow</span><span class="operator">.</span><span class="function associated consuming library">should_die</span><span class="parenthesis">(</span><span class="parenthesis">)</span> <span class="brace">{</span>
         foo::<span class="macro">die!</span><span class="parenthesis">(</span><span class="parenthesis">)</span><span class="semicolon">;</span>
     <span class="brace">}</span>
 <span class="brace">}</span>
diff --git a/crates/ide/src/syntax_highlighting/tests.rs b/crates/ide/src/syntax_highlighting/tests.rs
index be4447ebb..662b53481 100644
--- a/crates/ide/src/syntax_highlighting/tests.rs
+++ b/crates/ide/src/syntax_highlighting/tests.rs
@@ -232,7 +232,7 @@ fn use_foo_items() {
 
     let control_flow = foo::identity(foo::ControlFlow::Continue);
 
-    if let foo::ControlFlow::Die = control_flow {
+    if control_flow.should_die() {
         foo::die!();
     }
 }
@@ -249,6 +249,12 @@ pub enum ControlFlow {
     Die,
 }
 
+impl ControlFlow {
+    pub fn should_die(self) -> bool {
+        matches!(self, ControlFlow::Die)
+    }
+}
+
 pub fn identity<T>(x: T) -> T { x }
 
 pub mod consts {