Add mapbox_eternal (#1137)

* Add mapbox_eternal

* Fix compilation

packages/m/mapbox_eternal/patches/add_cstdint.patch

@@ -0,0 +1,12 @@
+diff --git a/include/mapbox/eternal.hpp b/include/mapbox/eternal.hpp
+index 10c2f82..ab92ccb 100644
+--- a/include/mapbox/eternal.hpp
++++ b/include/mapbox/eternal.hpp
+@@ -2,6 +2,7 @@
+ 
+ #include <utility>
+ #include <functional>
++#include <cstdint>
+ 
+ // GCC 4.9 compatibility
+ #if !defined(__clang__) && defined(__GNUC__) && __GNUC__ < 5

packages/m/mapbox_eternal/xmake.lua

@@ -0,0 +1,38 @@
+package("mapbox_eternal")
+
+    set_kind("library", {headeronly = true})
+    set_homepage("https://github.com/mapbox/eternal")
+    set_description("A C++14 compile-time/constexpr map and hash map with minimal binary footprint")
+    set_license("ISC")
+
+    set_urls("https://github.com/mapbox/eternal/archive/refs/tags/$(version).tar.gz",
+             "https://github.com/mapbox/eternal.git")
+
+    add_versions("v1.0.1", "7d799381b3786d0bd987eea75df2a81f581a64ee962e922a2f7a7d3d0c3d0421")
+    add_patches("v1.0.1", path.join(os.scriptdir(), "patches", "add_cstdint.patch"), "9a3724ec903fb9d8963ac1d144228f9b5800a102857ea80199b0251f254d89b4")
+
+    on_install(function (package)
+        os.cp("include/mapbox", package:installdir("include"))
+    end)
+
+    on_test(function (package)
+        assert(package:check_cxxsnippets({test = [[
+          struct Color
+          {
+              unsigned int r, g, b, a;
+          };
+          
+          constexpr auto colors = mapbox::eternal::map<mapbox::eternal::string, Color>({
+              { "red", { 255, 0, 0, 1 } },
+              { "green", { 0, 128, 0, 1 } },
+              { "yellow", { 255, 255, 0, 1 } },
+              { "white", { 255, 255, 255, 1 } },
+              { "black", { 0, 0, 0, 1 } }
+            });
+          
+            void test()
+            {
+                colors.contains("yellow");
+            }
+        ]]}, {configs = {languages = "c++14"}, includes = { "mapbox/eternal.hpp"} }))
+    end)