add versioning namespace with a test. Fixes #13

include/ankerl/unordered_dense.h

@@ -34,6 +34,13 @@
 #define ANKERL_UNORDERED_DENSE_VERSION_MINOR 3 // NOLINT(cppcoreguidelines-macro-usage) backwards compatible functionality
 #define ANKERL_UNORDERED_DENSE_VERSION_PATCH 0 // NOLINT(cppcoreguidelines-macro-usage) backwards compatible bug fixes
 
+// API versioning with inline namespace, see https://www.foonathan.net/2018/11/inline-namespaces/
+#define ANKERL_UNORDERED_DENSE_VERSION_CONCAT1(major, minor, patch) v##major##_##minor##_##patch
+#define ANKERL_UNORDERED_DENSE_VERSION_CONCAT(major, minor, patch) ANKERL_UNORDERED_DENSE_VERSION_CONCAT1(major, minor, patch)
+#define ANKERL_UNORDERED_DENSE_NAMESPACE   \
+    ANKERL_UNORDERED_DENSE_VERSION_CONCAT( \
+        ANKERL_UNORDERED_DENSE_VERSION_MAJOR, ANKERL_UNORDERED_DENSE_VERSION_MINOR, ANKERL_UNORDERED_DENSE_VERSION_PATCH)
+
 #if defined(_MSVC_LANG)
 #    define ANKERL_UNORDERED_DENSE_CPP_VERSION _MSVC_LANG
 #else
@@ -90,6 +97,7 @@
 #    endif
 
 namespace ankerl::unordered_dense {
+inline namespace ANKERL_UNORDERED_DENSE_NAMESPACE {
 
 // hash ///////////////////////////////////////////////////////////////////////
 
@@ -1347,6 +1355,7 @@ using set = detail::table<Key, void, Hash, KeyEqual, std::pmr::polymorphic_alloc
 // deduction guides for alias templates are only possible since C++20
 // see https://en.cppreference.com/w/cpp/language/class_template_argument_deduction
 
+} // namespace ANKERL_UNORDERED_DENSE_NAMESPACE
 } // namespace ankerl::unordered_dense
 
 // std extensions /////////////////////////////////////////////////////////////

test/meson.build

@@ -54,6 +54,7 @@ test_sources = [
     'unit/max.cpp',
     'unit/move_to_moved.cpp',
     'unit/multiple_apis.cpp',
+    'unit/namespace.cpp',
     'unit/not_copyable.cpp',
     'unit/not_moveable.cpp',
     'unit/pmr.cpp',

test/unit/namespace.cpp

@@ -0,0 +1,11 @@
+#include <ankerl/unordered_dense.h>
+
+#include <doctest.h>
+
+static_assert(std::is_same_v<ankerl::unordered_dense::v1_3_0::map<int, int>, ankerl::unordered_dense::map<int, int>>);
+static_assert(std::is_same_v<ankerl::unordered_dense::v1_3_0::hash<int>, ankerl::unordered_dense::hash<int>>);
+
+TEST_CASE("version_namespace") {
+    auto map = ankerl::unordered_dense::v1_3_0::map<int, int>{};
+    REQUIRE(map.empty());
+}