fix(napi-derive): an Option in front of a required parameter is no longer optional in TypeScript

This fixes a bug where having a parameter of type `Option<T>` followed by required parameters
would incorrectly declare the parameter as option in the TypeScript declaration file, resulting
in invalid syntax.

examples/napi/__test__/typegen.spec.ts.md

@@ -32,6 +32,10 @@ Generated by [AVA](https://avajs.dev).
     export function createBigInt(): bigint␊
     export function createBigIntI64(): bigint␊
     export function getCwd(callback: (arg0: string) => void): void␊
+    export function optionEnd(callback: (arg0: string, arg1?: string | undefined | null) => void): void␊
+    export function optionStart(callback: (arg0: string | undefined | null, arg1: string) => void): void␊
+    export function optionStartEnd(callback: (arg0: string | undefined | null, arg1: string, arg2?: string | undefined | null) => void): void␊
+    export function optionOnly(callback: (arg0?: string | undefined | null) => void): void␊
     /** napi = { version = 2, features = ["serde-json"] } */␊
     export function readFile(callback: (arg0: Error | undefined, arg1?: string | undefined | null) => void): void␊
     export function eitherStringOrNumber(input: string | number): number␊
@@ -208,6 +212,12 @@ Generated by [AVA](https://avajs.dev).
       constructor()␊
       get filePath(): number␊
     }␊
+    export class Optional {␊
+      static optionEnd(required: string, optional?: string | undefined | null): string␊
+      static optionStart(optional: string | undefined | null, required: string): string␊
+      static optionStartEnd(optional1: string | undefined | null, required: string, optional2?: string | undefined | null): string␊
+      static optionOnly(optional?: string | undefined | null): string␊
+    }␊
     export class ClassWithFactory {␊
       name: string␊
       static withName(name: string): ClassWithFactory␊

examples/napi/index.d.ts

@@ -22,6 +22,10 @@ export function bigintAdd(a: bigint, b: bigint): bigint
 export function createBigInt(): bigint
 export function createBigIntI64(): bigint
 export function getCwd(callback: (arg0: string) => void): void
+export function optionEnd(callback: (arg0: string, arg1?: string | undefined | null) => void): void
+export function optionStart(callback: (arg0: string | undefined | null, arg1: string) => void): void
+export function optionStartEnd(callback: (arg0: string | undefined | null, arg1: string, arg2?: string | undefined | null) => void): void
+export function optionOnly(callback: (arg0?: string | undefined | null) => void): void
 /** napi = { version = 2, features = ["serde-json"] } */
 export function readFile(callback: (arg0: Error | undefined, arg1?: string | undefined | null) => void): void
 export function eitherStringOrNumber(input: string | number): number
@@ -198,6 +202,12 @@ export class Asset {
   constructor()
   get filePath(): number
 }
+export class Optional {
+  static optionEnd(required: string, optional?: string | undefined | null): string
+  static optionStart(optional: string | undefined | null, required: string): string
+  static optionStartEnd(optional1: string | undefined | null, required: string, optional2?: string | undefined | null): string
+  static optionOnly(optional?: string | undefined | null): string
+}
 export class ClassWithFactory {
   name: string
   static withName(name: string): ClassWithFactory

examples/napi/src/callback.rs

@@ -6,6 +6,26 @@ fn get_cwd<T: Fn(String) -> Result<()>>(callback: T) {
   callback(env::current_dir().unwrap().to_string_lossy().to_string()).unwrap();
 }
 
+#[napi]
+fn option_end<T: Fn(String, Option<String>) -> Result<()>>(callback: T) {
+  callback("Hello".to_string(), None).unwrap();
+}
+
+#[napi]
+fn option_start<T: Fn(Option<String>, String) -> Result<()>>(callback: T) {
+  callback(None, "World".to_string()).unwrap();
+}
+
+#[napi]
+fn option_start_end<T: Fn(Option<String>, String, Option<String>) -> Result<()>>(callback: T) {
+  callback(None, "World".to_string(), None).unwrap();
+}
+
+#[napi]
+fn option_only<T: Fn(Option<String>) -> Result<()>>(callback: T) {
+  callback(None).unwrap();
+}
+
 /// napi = { version = 2, features = ["serde-json"] }
 #[napi]
 fn read_file<T: Fn(Result<()>, Option<String>) -> Result<()>>(callback: T) {

examples/napi/src/class.rs

@@ -237,3 +237,47 @@ impl JsAsset {
     return 1;
   }
 }
+
+#[napi]
+pub struct Optional {}
+
+#[napi]
+impl Optional {
+  #[napi]
+  pub fn option_end(required: String, optional: Option<String>) -> String {
+    match optional {
+      None => required,
+      Some(optional) => format!("{} {}", required, optional),
+    }
+  }
+
+  #[napi]
+  pub fn option_start(optional: Option<String>, required: String) -> String {
+    match optional {
+      None => required,
+      Some(optional) => format!("{} {}", optional, required),
+    }
+  }
+
+  #[napi]
+  pub fn option_start_end(
+    optional1: Option<String>,
+    required: String,
+    optional2: Option<String>,
+  ) -> String {
+    match (optional1, optional2) {
+      (None, None) => required,
+      (None, Some(optional2)) => format!("{} {}", required, optional2),
+      (Some(optional1), None) => format!("{} {}", optional1, required),
+      (Some(optional1), Some(optional2)) => format!("{} {} {}", optional1, required, optional2),
+    }
+  }
+
+  #[napi]
+  pub fn option_only(optional: Option<String>) -> String {
+    match optional {
+      None => "".to_string(),
+      Some(optional) => format!("{}", optional),
+    }
+  }
+}