Clang: Fix highlighting lambda captures

This fixes the basic case, but e.g. captures with initializers, e.g.
[foo=bar] are not properly reported by libclang and thus "bar" is still
not highlighted for this case.

Task-number: QTCREATORBUG-15271
Change-Id: I1a2d465f71b0ae1a0406ef9e77d88898e8637958
Reviewed-by: Marco Bubke <marco.bubke@qt.io>
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

src/tools/clangbackend/source/tokeninfo.cpp

@@ -372,7 +372,8 @@ void TokenInfo::identifierKind(const Cursor &cursor, Recursion recursion)
             break;
         case CXCursor_ParmDecl:
         case CXCursor_VarDecl:
-            variableKind(cursor);
+        case CXCursor_VariableRef:
+            variableKind(cursor.referenced());
             break;
         case CXCursor_DeclRefExpr:
             identifierKind(cursor.referenced(), Recursion::RecursivePass);

tests/unit/unittest/tokenprocessor-test.cpp

@@ -1697,6 +1697,13 @@ TEST_F(TokenProcessor, DISABLED_NonConstArgumentConstructor)
     ASSERT_THAT(infos[3], HasMixin(HighlightingType::OutputArgument));
 }
 
+TEST_F(TokenProcessor, LambdaLocalVariableCapture)
+{
+    const auto infos = translationUnit.tokenInfosInRange(sourceRange(442, 47));
+
+    ASSERT_THAT(infos[4], HasOnlyType(HighlightingType::LocalVariable));
+}
+
 Data *TokenProcessor::d;
 
 void TokenProcessor::SetUpTestCase()