highlights(cpp): add support for concepts

Requires https://github.com/tree-sitter/tree-sitter-cpp/pull/138

lockfile.json

@@ -27,13 +27,13 @@
     "revision": "4fd115d3bb7046cd094f21bfe5766c302dbf64cd"
   },
   "cpp": {
-    "revision": "e8dcc9d2b404c542fd236ea5f7208f90be8a6e89"
+    "revision": "049c2a4edeb6c19bacefb4d40aa03c6fdc175575"
   },
   "css": {
     "revision": "a03f1d2d1dfbf6f8e0fdca5f9ff030228241eb57"
   },
   "cuda": {
-    "revision": "bc20ed7a36031437a69a88ef368af4b9f1ecec70"
+    "revision": "61de33bc41231a2e7c1970542c505a42d62c98eb"
   },
   "d": {
     "revision": "c2fbf21bd3aa45495fe13247e040ad5815250032"

queries/cpp/highlights.scm

@@ -30,6 +30,8 @@
 (function_declarator
   declarator: (field_identifier) @method)
 
+(concept_definition
+  name: (identifier) @type)
 
 (namespace_identifier) @namespace
 ((namespace_identifier) @type
@@ -123,6 +125,8 @@
  "using"
  "virtual"
  "co_await"
+ "concept"
+ "requires"
  (auto)
 ] @keyword
 

tests/query/highlights/cpp/concepts.cpp

@@ -0,0 +1,22 @@
+
+template <class T, class U>
+concept Derived = std::is_base_of<U, T>::value;
+//  ^ keyword
+//       ^ type
+
+template<typename T>
+concept Hashable = requires(T a) {
+//                   ^ keyword
+//                            ^ parameter
+//                          ^ type
+    { std::hash<T>{}(a) } -> std::convertible_to<std::size_t>;
+ typename CommonType<T, U>; // CommonType<T, U> is valid and names a type
+    { CommonType<T, U>{std::forward<T>(t)} }; 
+    { CommonType<T, U>{std::forward<U>(u)} }; 
+};
+
+
+template<typename T>
+    requires requires (T x) { x + x; } // ad-hoc constraint, note keyword used twice
+//                 ^ keyword
+T add(T a, T b) { return a + b; }