Fix ethers-v5 code-generation for no-argument events

contracts/Events.sol

@@ -31,4 +31,6 @@ contract Events {
   function emit_event3_overloaded() public {
     emit Event3(1);
   }
+
+  event NoArgsEvent();
 }

packages/target-ethers-v4-test/types/Events.d.ts

@@ -40,6 +40,8 @@ interface EventsInterface extends Interface {
     Event3: TypedEventDescription<{
       encodeTopics([value1, value2]: [boolean | null, null]): string[];
     }>;
+
+    NoArgsEvent: TypedEventDescription<{ encodeTopics([]: []): string[] }>;
   };
 }
 
@@ -130,6 +132,8 @@ export class Events extends Contract {
     Event2(undefined: null): EventFilter;
 
     Event3(value1: boolean | null, value2: null): EventFilter;
+
+    NoArgsEvent(): EventFilter;
   };
 
   estimate: {

packages/target-ethers-v4-test/types/factories/Events__factory.ts

@@ -91,6 +91,12 @@ const _abi = [
     name: "Event3",
     type: "event",
   },
+  {
+    anonymous: false,
+    inputs: [],
+    name: "NoArgsEvent",
+    type: "event",
+  },
   {
     inputs: [],
     name: "emit_anon1",

packages/target-ethers-v5-test/types/Events.d.ts

@@ -74,12 +74,14 @@ interface EventsInterface extends ethers.utils.Interface {
     "Event1(uint256,uint256)": EventFragment;
     "Event2(uint256)": EventFragment;
     "Event3(bool,uint256)": EventFragment;
+    "NoArgsEvent()": EventFragment;
   };
 
   getEvent(nameOrSignatureOrTopic: "AnonEvent1"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "Event1"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "Event2"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "Event3"): EventFragment;
+  getEvent(nameOrSignatureOrTopic: "NoArgsEvent"): EventFragment;
 }
 
 export class Events extends Contract {
@@ -215,6 +217,8 @@ export class Events extends Contract {
       [boolean, BigNumber],
       { value1: boolean; value2: BigNumber }
     >;
+
+    NoArgsEvent(): TypedEventFilter<[], {}>;
   };
 
   estimateGas: {

packages/target-ethers-v5-test/types/factories/Events__factory.ts

@@ -91,6 +91,12 @@ const _abi = [
     name: "Event3",
     type: "event",
   },
+  {
+    anonymous: false,
+    inputs: [],
+    name: "NoArgsEvent",
+    type: "event",
+  },
   {
     inputs: [],
     name: "emit_anon1",

packages/target-ethers-v5/src/codegen/index.ts

@@ -274,11 +274,15 @@ function generateParamNames(params: Array<AbiParameter | EventArgDeclaration>):
 }
 
 function generateEvents(event: EventDeclaration) {
+  const outputTypes =
+    event.inputs.length > 0
+      ? generateOutputTypes(
+          true,
+          event.inputs.map((input, i) => ({ name: input.name ?? `arg${i.toString()}`, type: input.type })),
+        ).replace(' &', ',')
+      : '[], {}'
   return `
-  ${event.name}(${generateEventTypes(event.inputs)}): TypedEventFilter<${generateOutputTypes(
-    true,
-    event.inputs.map((input, i) => ({ name: input.name ?? `arg${i.toString()}`, type: input.type })),
-  ).replace(' &', ',')}>;
+  ${event.name}(${generateEventTypes(event.inputs)}): TypedEventFilter<${outputTypes}>;
 `
 }
 

packages/target-truffle-v4-test/types/truffle-contracts/Events.d.ts

@@ -40,7 +40,12 @@ export interface Event3_uint256 {
 
 type Event3 = Event3_bool_uint256 | Event3_uint256;
 
-type AllEvents = Event1 | Event3;
+export interface NoArgsEvent {
+  name: "NoArgsEvent";
+  args: {};
+}
+
+type AllEvents = Event1 | Event3 | NoArgsEvent;
 
 export interface EventsInstance extends Truffle.ContractInstance {
   emit_event1: {

packages/target-truffle-v5-test/types/truffle-contracts/Events.d.ts

@@ -54,7 +54,12 @@ export interface Event3_uint256 {
 
 type Event3 = Event3_bool_uint256 | Event3_uint256;
 
-type AllEvents = Event1 | Event2 | Event3;
+export interface NoArgsEvent {
+  name: "NoArgsEvent";
+  args: {};
+}
+
+type AllEvents = Event1 | Event2 | Event3 | NoArgsEvent;
 
 export interface EventsInstance extends Truffle.ContractInstance {
   emit_event1: {

packages/target-web3-v1-test/types/Events.d.ts

@@ -44,6 +44,7 @@ export type Event3_uint256 = ContractEventLog<{
   value1: string;
   0: string;
 }>;
+export type NoArgsEvent = ContractEventLog<{}>;
 
 export interface Events extends BaseContract {
   constructor(
@@ -82,6 +83,12 @@ export interface Events extends BaseContract {
       cb?: Callback<Event3_uint256>
     ): EventEmitter;
 
+    NoArgsEvent(cb?: Callback<NoArgsEvent>): EventEmitter;
+    NoArgsEvent(
+      options?: EventOptions,
+      cb?: Callback<NoArgsEvent>
+    ): EventEmitter;
+
     allEvents(options?: EventOptions, cb?: Callback<EventLog>): EventEmitter;
   };
 
@@ -90,4 +97,11 @@ export interface Events extends BaseContract {
 
   once(event: "Event2", cb: Callback<Event2>): void;
   once(event: "Event2", options: EventOptions, cb: Callback<Event2>): void;
+
+  once(event: "NoArgsEvent", cb: Callback<NoArgsEvent>): void;
+  once(
+    event: "NoArgsEvent",
+    options: EventOptions,
+    cb: Callback<NoArgsEvent>
+  ): void;
 }