BridgeJS: Check thrown errors before lifting return values

Author: krodak

Plugins/BridgeJS/Sources/BridgeJSLink/BridgeJSLink.swift

@@ -1809,6 +1809,7 @@ public struct BridgeJSLink {
                 body.write("const \(returnVariable) = \(call);")
                 fragmentArguments = [returnVariable]
             }
+            body.write(lines: checkExceptionLines())
             let liftedValues = try liftingFragment.printCode(fragmentArguments, context)
             assert(liftedValues.count <= 1, "Lifting fragment should produce at most one value")
             return liftedValues.first
@@ -1818,10 +1819,11 @@ public struct BridgeJSLink {
             let call =
                 "\(JSGlueVariableScope.reservedInstance).exports.\(abiName)(\(parameterForwardings.joined(separator: ", ")))"
             body.write("const ret = \(call);")
+            body.write(lines: checkExceptionLines())
             return "ret"
         }
 
-        func checkExceptionLines() -> [String] {
+        private func checkExceptionLines() -> [String] {
             guard effects.isThrows else {
                 return []
             }
@@ -1837,10 +1839,9 @@ public struct BridgeJSLink {
             ]
         }
 
-        /// Renders the thunk body (body code, exception handling, and optional return) into a printer.
+        /// Renders the thunk body and optional return; `call`/`callConstructor` put the exception check in `body`.
         func renderFunctionBody(into printer: CodeFragmentPrinter, returnExpr: String?) {
             printer.write(contentsOf: body)
-            printer.write(lines: checkExceptionLines())
             if let returnExpr = returnExpr {
                 printer.write("return \(returnExpr);")
             }
@@ -3490,7 +3491,6 @@ extension BridgeJSLink {
                 getterPrinter.write("get \(property.resolvedJSName)() {")
                 getterPrinter.indent {
                     getterPrinter.write(contentsOf: getterThunkBuilder.body)
-                    getterPrinter.write(lines: getterThunkBuilder.checkExceptionLines())
                     if let returnExpr = getterReturnExpr {
                         getterPrinter.write("return \(returnExpr);")
                     }
@@ -3517,7 +3517,6 @@ extension BridgeJSLink {
                     setterPrinter.write("set \(property.resolvedJSName)(\(setterThunkBuilder.parameterList)) {")
                     setterPrinter.indent {
                         setterPrinter.write(contentsOf: setterThunkBuilder.body)
-                        setterPrinter.write(lines: setterThunkBuilder.checkExceptionLines())
                     }
                     setterPrinter.write("},")
 

Plugins/BridgeJS/Tests/BridgeJSToolTests/Inputs/MacroSwift/ThrowingReturns.swift

@@ -0,0 +1,72 @@
+import JavaScriptKit
+
+@JS protocol ThrowingDelegate {
+    func notify()
+}
+
+@JS class ThrowingBox {
+    @JS init(value: Int) throws(JSException) {}
+
+    @JS func method() throws(JSException) -> JSObject {
+        return JSObject()
+    }
+
+    @JS static func staticMethod() throws(JSException) -> ThrowingBox {
+        return try ThrowingBox(value: 0)
+    }
+}
+
+@JS struct ThrowingPoint {
+    var x: Int
+
+    @JS func method() throws(JSException) -> JSObject {
+        return JSObject()
+    }
+
+    @JS static func staticMethod() throws(JSException) -> JSObject {
+        return JSObject()
+    }
+}
+
+@JS enum ThrowingDirection {
+    case north
+    case south
+
+    @JS static func staticMethod() throws(JSException) -> JSObject {
+        return JSObject()
+    }
+}
+
+@JS enum ThrowingTheme: String {
+    case light
+    case dark
+}
+
+@JS enum ThrowingPayload {
+    case value(Int)
+    case message(String)
+}
+
+@JS enum ThrowingNamespace {
+    @JS static func namespaced() throws(JSException) -> JSObject {
+        return JSObject()
+    }
+}
+
+@JS func throwingVoid() throws(JSException) {}
+@JS func throwingInt() throws(JSException) -> Int { 0 }
+@JS func throwingString() throws(JSException) -> String { "" }
+@JS func throwingJSObject() throws(JSException) -> JSObject { JSObject() }
+@JS func throwingOptionalJSObject() throws(JSException) -> JSObject? { nil }
+@JS func throwingJSValue() throws(JSException) -> JSValue { .undefined }
+@JS func throwingProtocol() throws(JSException) -> ThrowingDelegate { fatalError() }
+@JS func throwingClass() throws(JSException) -> ThrowingBox { try ThrowingBox(value: 0) }
+@JS func throwingOptionalClass() throws(JSException) -> ThrowingBox? { nil }
+@JS func throwingClosure() throws(JSException) -> (Int) -> Int { { $0 } }
+@JS func throwingStruct() throws(JSException) -> ThrowingPoint { ThrowingPoint(x: 0) }
+@JS func throwingCaseEnum() throws(JSException) -> ThrowingDirection { .north }
+@JS func throwingRawValueEnum() throws(JSException) -> ThrowingTheme { .light }
+@JS func throwingAssociatedValueEnum() throws(JSException) -> ThrowingPayload { .value(0) }
+@JS func throwingArray() throws(JSException) -> [Int] { [] }
+@JS func throwingDictionary() throws(JSException) -> [String: Int] { [:] }
+@JS func throwingAsync() async throws(JSException) -> JSObject { JSObject() }