Add meta module

asl/meta/BUILD.bazel

@@ -0,0 +1,18 @@
+cc_library(
+    name = "meta",
+    hdrs = [
+        "types.hpp",
+    ],
+    visibility = ["//visibility:public"],
+)
+
+cc_test(
+    name = "types_tests",
+    srcs = [
+        "types_tests.cpp",
+    ],
+    deps = [
+        ":meta",
+    ],
+)
+

asl/meta/types.hpp

@@ -0,0 +1,14 @@
+#pragma once
+
+namespace asl {
+
+template<typename T> using void_t = void;
+
+template<typename T, typename = void>
+inline constexpr bool referenceable = false;
+
+template<typename T>
+inline constexpr bool referenceable<T, void_t<T&>> = true;
+
+} // namespace asl
+

asl/meta/types_tests.cpp

@@ -0,0 +1,16 @@
+#include "asl/meta/types.hpp"
+
+using namespace asl;
+
+static_assert(referenceable<int>);
+static_assert(referenceable<int&>);
+static_assert(referenceable<int&&>);
+static_assert(!referenceable<void>);
+static_assert(referenceable<void*>);
+static_assert(referenceable<void()>);
+static_assert(referenceable<void(*)()>);
+static_assert(!referenceable<void() const>);
+static_assert(!referenceable<void() &>);
+static_assert(!referenceable<void() const &&>);
+
+int main() { return 0; }