Add library compatibility check

Author: kateinoigakukun

Package.swift

@@ -19,7 +19,9 @@ let package = Package(
                         "-Xlinker",
                         "--export=swjs_prepare_host_function_call",
                         "-Xlinker",
-                        "--export=swjs_cleanup_host_function_call"
+                        "--export=swjs_cleanup_host_function_call",
+                        "-Xlinker",
+                        "--export=swjs_library_version",
                     ],
                     .when(platforms: [.wasi])
                 )

Package@swift-5.2.swift

@@ -19,7 +19,9 @@ let package = Package(
                         "-Xlinker",
                         "--export=swjs_prepare_host_function_call",
                         "-Xlinker",
-                        "--export=swjs_cleanup_host_function_call"
+                        "--export=swjs_cleanup_host_function_call",
+                        "-Xlinker",
+                        "--export=swjs_library_version",
                     ]
                 )
             ]),

Runtime/src/index.ts

@@ -10,6 +10,7 @@ declare const window: GlobalVariable;
 declare const global: GlobalVariable;
 
 interface SwiftRuntimeExportedFunctions {
+    swjs_library_version(): number;
     swjs_prepare_host_function_call(size: number): pointer;
     swjs_cleanup_host_function_call(argv: pointer): void;
     swjs_call_host_function(
@@ -84,6 +85,7 @@ class SwiftRuntimeHeap {
 export class SwiftRuntime {
     private instance: WebAssembly.Instance | null;
     private heap: SwiftRuntimeHeap
+    private version: number = 400
 
     constructor() {
         this.instance = null;
@@ -92,6 +94,10 @@ export class SwiftRuntime {
 
     setInstance(instance: WebAssembly.Instance) {
         this.instance = instance
+        const exports = this.instance.exports as any as SwiftRuntimeExportedFunctions;
+        if (exports.swjs_library_version() != this.version) {
+          throw new Error("The versions of JavaScriptKit are incompatible.")
+        }
     }
 
     importObjects() {
@@ -351,4 +357,4 @@ export class SwiftRuntime {
             }
         }
     }
-}
+}

Sources/JavaScriptKit/Compatibility.swift

@@ -0,0 +1,4 @@
+@_cdecl("swjs_library_version")
+func _library_version() -> Double {
+    return 400
+}