D GC for WebAssembly

[kassane]

Note

OpenD (D-fork), based on dmd-2.106 front-end (ldc2 v1.36.0) - upstream compat.
However, no have dub binary in opend tarballs.

Idea is to try using D features but without having to rewrite because of DRT (garbage collector) use.

Based info,
https://dpldocs.info/this-week-in-arsd/Blog.Posted_2024_10_25.html#xpack-emscripten (prebuilt druntime + phobos2 libs).
This solution follows on from an experiment referenced in #7 by @adamdruppe.

OpenD build sokol-d?

[adamdruppe]

does that mean it worked?

[kassane]

https://github.com/kassane/sokol-d/blob/de11612629c76bfd8ec6cbd7ca3efebaf36a10d5/src/examples/cube.d#L6-L13

works, -i=std -i=sokol -i=shaders -i=handmade

But std.stdio.writef emit:

/home/kassane/sokol-d/src/examples/cube.d(13): Deprecation: from file cube.d should be imported with 'import shaders.cube;'
/home/kassane/zig/opend-latest-linux-x86_64/bin/../import/std/stdio.d(3711): Error: `@safe` function `std.stdio.File.size` cannot call `@system` function `std.exception.collectException!(Exception, ulong).collectException`
/home/kassane/zig/opend-latest-linux-x86_64/bin/../import/std/exception.d(720):        which wasn't inferred `@safe` because of:
/home/kassane/zig/opend-latest-linux-x86_64/bin/../import/std/exception.d(720):        scope variable `t` may not be returned
/home/kassane/zig/opend-latest-linux-x86_64/bin/../import/std/exception.d(712):        `std.exception.collectException!(Exception, ulong).collectException` is declared here
/home/kassane/zig/opend-latest-linux-x86_64/bin/../import/std/string.d(6607): Error: `@safe` function `std.string.abbrev` cannot call `@system` function `std.algorithm.sorting.sort!("a < b", SwapStrategy.unstable, string[]).sort`
/home/kassane/zig/opend-latest-linux-x86_64/bin/../import/std/algorithm/sorting.d(1925):        `std.algorithm.sorting.sort!("a < b", SwapStrategy.unstable, string[]).sort` is declared here
/home/kassane/zig/opend-latest-linux-x86_64/bin/../import/std/uni/package.d(2888): Error: `@safe` function `std.uni.InversionList!(GcPolicy).InversionList.sanitize` cannot call `@system` function `std.uni.InversionList!(GcPolicy).InversionList.sanitize.sort!((a, b) => a.a < b.a, SwapStrategy.stable, Intervals!(uint[])).sort`
/home/kassane/zig/opend-latest-linux-x86_64/bin/../import/std/algorithm/sorting.d(2369):        which calls `std.uni.InversionList!(GcPolicy).InversionList.sanitize.sort!().sort`
/home/kassane/zig/opend-latest-linux-x86_64/bin/../import/std/algorithm/sorting.d(2546):        which calls `std.uni.InversionList!(GcPolicy).InversionList.sanitize.mergeAt!().mergeAt`
/home/kassane/zig/opend-latest-linux-x86_64/bin/../import/std/algorithm/sorting.d(2570):        which calls `std.uni.InversionList!(GcPolicy).InversionList.sanitize.merge!().merge`
/home/kassane/zig/opend-latest-linux-x86_64/bin/../import/std/algorithm/sorting.d(2637):        which calls `std.uni.InversionList!(GcPolicy).InversionList.sanitize.mergeLo!().mergeLo`
/home/kassane/zig/opend-latest-linux-x86_64/bin/../import/std/algorithm/sorting.d(1925):        `std.uni.InversionList!(GcPolicy).InversionList.sanitize.sort!((a, b) => a.a < b.a, SwapStrategy.stable, Intervals!(uint[])).sort` is declared here
/home/kassane/zig/opend-latest-linux-x86_64/bin/../import/std/uni/package.d(1962): Error: template instance `std.uni.InversionList!(GcPolicy)` error instantiating

[kassane]

OpenD xpack-emscripten in zig build (buildrunner) works if disable use_emmalloc, no black-screen
https://github.com/kassane/sokol-d/blob/0b26d447e29564bda797deccac46c0c4e2719d32/build.zig#L589
Need only add druntime in

@@ -809,6 +811,7 @@ pub fn emLinkStep(b: *Build, options: EmLinkOptions) !*Build.Step.InstallDir {
         emcc.addArg(arg);
     }
 
+    emcc.addFileArg(path(b, "/home/kassane/zig/opend-latest-linux-x86_64/xpacks/opend-latest-xpack-emscripten/lib/libdruntime-ldc.a"));
     // add the main lib, and then scan for library dependencies and add those too
     emcc.addArtifactArg(options.lib_main);
     var it = options.lib_main.root_module.iterateDependencies(options.lib_main, false);

More likely, it allows zig to get xpack-emscripten from the zon file, like the rest of the dependencies.

---

@@ -809,6 +811,9 @@ pub fn emLinkStep(b: *Build, options: EmLinkOptions) !*Build.Step.InstallDir {
         emcc.addArg(arg);
     }
 
+    const xpack = b.dependency("xpack", .{}).path("lib").getPath(b);
+
+    emcc.addFileArg(path(b, b.fmt("{s}/libdruntime-ldc.a", .{xpack})));
     // add the main lib, and then scan for library dependencies and add those too
     emcc.addArtifactArg(options.lib_main);
     var it = options.lib_main.root_module.iterateDependencies(options.lib_main, false);
diff --git a/build.zig.zon b/build.zig.zon
index 56a72de..dec1763 100644
--- a/build.zig.zon
+++ b/build.zig.zon
@@ -23,5 +23,9 @@
             .url = "git+https://github.com/floooh/sokol-tools-bin#3388e3b2c04b532a55b072d79e77c9fc44c3ca50",
             .hash = "1220bd7b3c90b9b827145dfb25cf35fa2bfbb1d04ff597d5540eda06b97f3fb612a7",
         },
+        .xpack = .{
+            .url = "https://github.com/opendlang/opend/releases/download/CI/opend-latest-xpack-emscripten.tar.xz",
+            .hash = "12207ff27668e40a4054a60bda3fd33c3d49c603a8b06c568afad536a969ccf3c410",
+        },
     },
 }

[adamdruppe]

Try removing that -preview=all thing, looks like some dip1000 spam from phobos there. "scope variable t may not be returned" is a dip1000 thing and dip1000 isn't really supported (by anybody, hence why it is hidden behind a preview switch). But also possible there's some bug in the safe.

Note that the hash of xpacks are subject to change at any time; if I git push master it is likely to change that hash as it overwrites the file.

[kassane]

-preview=all

Ok, replacing to -preview=rvaluerefparam only (required by shaders.* - autogenerated @safe compat).

[kassane]

sample: https://github.com/kassane/sokol-d/blob/main/src/examples/user_data.d

diff changes

-void frame_userdata(scope void* userdata) @trusted {
+void frame_userdata(scope void* userdata) @trusted
+{
     auto state = cast(ExampleUserData*) userdata;
 
     state.data++;
-    version (WebAssembly) {
-        // TODO support
-    }
-    else {
-        if (state.data % 13 == 0) {
-            state.map[state.data] = state.data * 13 / 3;
-        }
-        if (state.data % 12 == 0 && state.data % 15 == 0) {
-            state.map.clear();
-        }
+
+    if (state.data % 13 == 0)
+    {
+        state.map[state.data] = state.data * 13 / 3;
     }
-    debug {
-        import std.stdio : writeln;
-        try {
-            writeln(*state);
-        } catch (Exception) { }
+    if (state.data % 12 == 0 && state.data % 15 == 0)
+    {
+        state.map.clear();
     }
 
-    sg.Pass pass = { swapchain: sglue.swapchain };
+    import std.stdio : writeln;
+
+    writeln(*state);
+
+    sg.Pass pass = {swapchain: sglue.swapchain};
     sg.beginPass(pass);
     sg.endPass();
     sg.commit();
 }