Pass host import arguments with their WebAssembly types

CHANGELOG.md

@@ -1,3 +1,7 @@
+# 1.1.1
+
+- Fixed host import arguments arriving as `double` instead of their WebAssembly types (#18) @michaelthyregod
+
 # 1.1.0
 
 Released on Friday, August 21 2026.

src/AngleSharp.Wasm.Tests/WasmtimeRuntimeTests.cs

@@ -1,6 +1,8 @@
 namespace AngleSharp.Wasm.Tests;
 
 using System;
+using System.Collections.Generic;
+using System.Linq;
 using System.Threading.Tasks;
 using NUnit.Framework;
 
@@ -43,6 +45,21 @@ public sealed class WasmtimeRuntimeTests
         0x0A, 0x09, 0x01, 0x07, 0x00, 0x10, 0x00, 0x41, 0x01, 0x6A, 0x0B,
     };
 
+    // (module
+    //   (import "host" "echo" (func $echo (param i32 i64 f32 f64)))
+    //   (func (export "run") (param i32 i64 f32 f64)
+    //     local.get 0 local.get 1 local.get 2 local.get 3 call $echo))
+    private static readonly byte[] HostImportArgumentsModule =
+    {
+        0x00, 0x61, 0x73, 0x6D,
+        0x01, 0x00, 0x00, 0x00,
+        0x01, 0x08, 0x01, 0x60, 0x04, 0x7F, 0x7E, 0x7D, 0x7C, 0x00,
+        0x02, 0x0D, 0x01, 0x04, 0x68, 0x6F, 0x73, 0x74, 0x04, 0x65, 0x63, 0x68, 0x6F, 0x00, 0x00,
+        0x03, 0x02, 0x01, 0x00,
+        0x07, 0x07, 0x01, 0x03, 0x72, 0x75, 0x6E, 0x00, 0x01,
+        0x0A, 0x0E, 0x01, 0x0C, 0x00, 0x20, 0x00, 0x20, 0x01, 0x20, 0x02, 0x20, 0x03, 0x10, 0x00, 0x0B,
+    };
+
     [Test]
     public async Task CanCompileInstantiateAndInvokeExport()
     {
@@ -97,4 +114,34 @@ public async Task CanInstantiateWithHostImport()
 
         Assert.That(Convert.ToInt32(result), Is.EqualTo(42));
     }
+
+    [Test]
+    public async Task HostImportReceivesArgumentsWithTheirWasmTypes()
+    {
+        using var runtime = new WasmtimeWasmRuntime();
+        using var module = await runtime.CompileAsync(HostImportArgumentsModule).ConfigureAwait(false);
+        var types = new[] { WasmValueType.Int32, WasmValueType.Int64, WasmValueType.Float32, WasmValueType.Float64 };
+        IReadOnlyList<object?>? received = null;
+
+        var imports = new[]
+        {
+            new WasmImportFunction(
+                "host",
+                "echo",
+                types,
+                Array.Empty<WasmValueType>(),
+                arguments =>
+                {
+                    received = arguments;
+                    return null;
+                }),
+        };
+
+        using var instance = await runtime.InstantiateAsync(module, imports).ConfigureAwait(false);
+        await instance.InvokeAsync("run", new object?[] { 7, 9007199254740993L, 1.5f, 2.25 }).ConfigureAwait(false);
+
+        Assert.That(received, Is.EqualTo(new object?[] { 7, 9007199254740993L, 1.5f, 2.25 }));
+        Assert.That(received!.Select(argument => argument?.GetType()),
+            Is.EqualTo(new[] { typeof(int), typeof(long), typeof(float), typeof(double) }));
+    }
 }

src/AngleSharp.Wasm/WasmtimeWasmRuntime.cs

@@ -126,10 +126,10 @@ private static void BindImport(Linker linker, WasmImportFunction import)
         {
             converted[i] = types[i] switch
             {
-                WasmValueType.Int32 => arguments[i].AsInt32(),
-                WasmValueType.Int64 => arguments[i].AsInt64(),
-                WasmValueType.Float32 => arguments[i].AsSingle(),
-                WasmValueType.Float64 => arguments[i].AsDouble(),
+                WasmValueType.Int32 => (object)arguments[i].AsInt32(),
+                WasmValueType.Int64 => (object)arguments[i].AsInt64(),
+                WasmValueType.Float32 => (object)arguments[i].AsSingle(),
+                WasmValueType.Float64 => (object)arguments[i].AsDouble(),
                 _ => throw new NotSupportedException($"Unsupported argument type '{types[i]}'."),
             };
         }