adjustments for experimental embedded support (#53)

* no print in embedded and renamed env setting

* add embedded wasm CI

* fix github CI file

* ...yaml...

* fixed missing function

.github/workflows/ci-embedded.yaml

@@ -0,0 +1,35 @@
+name: Build Embedded Wasm
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - "**.swift"
+      - "**.yml"
+  pull_request:
+    branches: [main]
+  workflow_dispatch:
+
+jobs:
+  linux:
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    strategy:
+      matrix:
+        image: ["swiftlang/swift:nightly-main"]
+
+    container:
+      image: ${{ matrix.image }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Build
+        run: |
+          swift build -c release \
+          --triple wasm32-unknown-none-wasm  \
+          -Xswiftc -enable-experimental-feature -Xswiftc Embedded \
+          -Xswiftc -enable-experimental-feature -Xswiftc Extern \
+          -Xswiftc -wmo -Xswiftc -disable-cmo \
+          -Xswiftc -cxx-interoperability-mode=default \
+          -Xcc -fdeclspec

Package@swift-6.swift

@@ -2,13 +2,15 @@
 import Foundation
 import PackageDescription
 
-let shouldBuildForEmbedded = ProcessInfo.processInfo.environment["EXPERIMENTAL_EMBEDDED_WASM"].flatMap(Bool.init) ?? false
+let shouldBuildForEmbedded = ProcessInfo.processInfo.environment["JAVASCRIPTKIT_EXPERIMENTAL_EMBEDDED_WASM"].flatMap(Bool.init) ?? false
 
 var featureFlags: [SwiftSetting] = [
     .enableUpcomingFeature("ExistentialAny"),
 ]
 
 if shouldBuildForEmbedded {
+    // currently this work-around only works for SwiftPM package dependencies on branches, not version tags
+    // see https://github.com/swiftlang/swift-package-manager/issues/7612
     featureFlags.append(
         .unsafeFlags([
             "-Xfrontend", "-emit-empty-object-file",

Sources/Elementary/Rendering/RenderingUtils.swift

@@ -12,9 +12,12 @@ extension _RenderingContext {
     @inline(__always)
     @usableFromInline
     func assertionFailureNoAsyncContext(_ type: (some HTML).Type) {
+        #if hasFeature(Embedded)
+        assertionFailure("Cannot render async content in a synchronous context, please use .render(into:) or .renderAsync() instead.")
+        #else
         let message = "Cannot render \(type) in a synchronous context, please use .render(into:) or .renderAsync() instead."
         print("Elementary rendering error: \(message)")
-        #if !hasFeature(Embedded)
+
         assertionFailure(message)
         #endif
     }