fix(ast): serialize Function.params like estree (#8772)

- part of #2854

This PR attempts to handle estree ast incompatibility of
`Function.params: FormalParameters` as mentioned in the above issue:

> `FormalParameters` is closer to ESTree now, but should be inlined
directly into `<node>.params` in multiple nodes.

Estree spec has `Function.params: Pattern[]`
https://github.com/estree/estree/blob/master/es5.md#functions, but oxc
already has `interface Pattern`, so I named it to `Function.params:
ParamPattern[]` for now.

Also I'm not sure about the testing (I suppose that's a part of
#8630), so I snapshoted one
example code. For comparison, here is acorn's output
https://astexplorer.net/#/gist/25138c0605f82dcfc1a8fd363dc2a681/5ad30d36c9f276519063e6fd2e340c113d8c85b0

---------

Co-authored-by: overlookmotel <theoverlookmotel@gmail.com>

Author: hi-ogawa

crates/oxc_ast/src/ast/js.rs

@@ -1552,6 +1552,9 @@ pub struct BindingRestElement<'a> {
 )]
 #[derive(Debug)]
 #[generate_derive(CloneIn, GetSpan, GetSpanMut, ContentEq, ESTree)]
+// https://github.com/estree/estree/blob/master/es5.md#patterns
+// https://github.com/DefinitelyTyped/DefinitelyTyped/blob/cd61c555bfc93e985b313263a42ed78074570d08/types/estree/index.d.ts#L411
+#[estree(add_ts_def = "type ParamPattern = FormalParameter | FormalParameterRest")]
 pub struct Function<'a> {
     pub span: Span,
     pub r#type: FunctionType,
@@ -1590,6 +1593,7 @@ pub struct Function<'a> {
     /// Function parameters.
     ///
     /// Does not include `this` parameters used by some TypeScript functions.
+    #[estree(ts_type = "ParamPattern[]")]
     pub params: Box<'a, FormalParameters<'a>>,
     /// The TypeScript return type annotation.
     #[ts]
@@ -1651,10 +1655,15 @@ pub struct FormalParameters<'a> {
 #[generate_derive(CloneIn, GetSpan, GetSpanMut, ContentEq, ESTree)]
 // Pluralize as `FormalParameterList` to avoid naming clash with `FormalParameters`.
 #[plural(FormalParameterList)]
+#[estree(no_type)]
 pub struct FormalParameter<'a> {
     pub span: Span,
     #[ts]
     pub decorators: Vec<'a, Decorator<'a>>,
+    #[estree(
+        flatten,
+        ts_type = "(BindingIdentifier | ObjectPattern | ArrayPattern | AssignmentPattern)"
+    )]
     pub pattern: BindingPattern<'a>,
     #[ts]
     pub accessibility: Option<TSAccessibility>,
@@ -1704,6 +1713,7 @@ pub struct ArrowFunctionExpression<'a> {
     pub r#async: bool,
     #[ts]
     pub type_parameters: Option<Box<'a, TSTypeParameterDeclaration<'a>>>,
+    #[estree(ts_type = "ParamPattern[]")]
     pub params: Box<'a, FormalParameters<'a>>,
     #[ts]
     pub return_type: Option<Box<'a, TSTypeAnnotation<'a>>>,

crates/oxc_ast/src/ast/ts.rs

@@ -973,6 +973,7 @@ pub struct TSCallSignatureDeclaration<'a> {
     pub span: Span,
     pub type_parameters: Option<Box<'a, TSTypeParameterDeclaration<'a>>>,
     pub this_param: Option<TSThisParameter<'a>>,
+    #[estree(ts_type = "ParamPattern[]")]
     pub params: Box<'a, FormalParameters<'a>>,
     pub return_type: Option<Box<'a, TSTypeAnnotation<'a>>>,
 }
@@ -1009,6 +1010,7 @@ pub struct TSMethodSignature<'a> {
     pub kind: TSMethodSignatureKind,
     pub type_parameters: Option<Box<'a, TSTypeParameterDeclaration<'a>>>,
     pub this_param: Option<Box<'a, TSThisParameter<'a>>>,
+    #[estree(ts_type = "ParamPattern[]")]
     pub params: Box<'a, FormalParameters<'a>>,
     pub return_type: Option<Box<'a, TSTypeAnnotation<'a>>>,
     pub scope_id: Cell<Option<ScopeId>>,
@@ -1022,6 +1024,7 @@ pub struct TSMethodSignature<'a> {
 pub struct TSConstructSignatureDeclaration<'a> {
     pub span: Span,
     pub type_parameters: Option<Box<'a, TSTypeParameterDeclaration<'a>>>,
+    #[estree(ts_type = "ParamPattern[]")]
     pub params: Box<'a, FormalParameters<'a>>,
     pub return_type: Option<Box<'a, TSTypeAnnotation<'a>>>,
     pub scope_id: Cell<Option<ScopeId>>,
@@ -1343,6 +1346,7 @@ pub struct TSFunctionType<'a> {
     /// ```
     pub this_param: Option<Box<'a, TSThisParameter<'a>>>,
     /// Function parameters. Akin to [`Function::params`].
+    #[estree(ts_type = "ParamPattern[]")]
     pub params: Box<'a, FormalParameters<'a>>,
     /// Return type of the function.
     /// ```ts
@@ -1359,6 +1363,7 @@ pub struct TSConstructorType<'a> {
     pub span: Span,
     pub r#abstract: bool,
     pub type_parameters: Option<Box<'a, TSTypeParameterDeclaration<'a>>>,
+    #[estree(ts_type = "ParamPattern[]")]
     pub params: Box<'a, FormalParameters<'a>>,
     pub return_type: Box<'a, TSTypeAnnotation<'a>>,
 }

crates/oxc_ast/src/generated/derive_estree.rs

@@ -1355,10 +1355,9 @@ impl Serialize for FunctionType {
 impl Serialize for FormalParameter<'_> {
     fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
         let mut map = serializer.serialize_map(None)?;
-        map.serialize_entry("type", "FormalParameter")?;
         self.span.serialize(serde::__private::ser::FlatMapSerializer(&mut map))?;
         map.serialize_entry("decorators", &self.decorators)?;
-        map.serialize_entry("pattern", &self.pattern)?;
+        self.pattern.serialize(serde::__private::ser::FlatMapSerializer(&mut map))?;
         map.serialize_entry("accessibility", &self.accessibility)?;
         map.serialize_entry("readonly", &self.readonly)?;
         map.serialize_entry("override", &self.r#override)?;

crates/oxc_ast/src/serialize.rs

@@ -11,10 +11,10 @@ use oxc_span::{Atom, Span};
 use oxc_syntax::number::BigintBase;
 
 use crate::ast::{
-    BigIntLiteral, BindingPatternKind, BooleanLiteral, Directive, Elision, FormalParameter,
-    FormalParameterKind, FormalParameters, JSXElementName, JSXIdentifier,
-    JSXMemberExpressionObject, NullLiteral, NumericLiteral, Program, RegExpFlags, RegExpLiteral,
-    RegExpPattern, Statement, StringLiteral, TSModuleBlock, TSTypeAnnotation,
+    BigIntLiteral, BindingPatternKind, BooleanLiteral, Directive, Elision, FormalParameters,
+    JSXElementName, JSXIdentifier, JSXMemberExpressionObject, NullLiteral, NumericLiteral, Program,
+    RegExpFlags, RegExpLiteral, RegExpPattern, Statement, StringLiteral, TSModuleBlock,
+    TSTypeAnnotation,
 };
 
 #[derive(Serialize)]
@@ -187,24 +187,10 @@ impl Serialize for FormalParameters<'_> {
             type_annotation: &rest.argument.type_annotation,
             optional: rest.argument.optional,
         });
-        let converted = SerFormalParameters {
-            span: self.span,
-            kind: self.kind,
-            items: ElementsAndRest::new(&self.items, converted_rest.as_ref()),
-        };
-        converted.serialize(serializer)
+        ElementsAndRest::new(&self.items, converted_rest.as_ref()).serialize(serializer)
     }
 }
 
-#[derive(Serialize)]
-#[serde(tag = "type", rename = "FormalParameters")]
-struct SerFormalParameters<'a, 'b> {
-    #[serde(flatten)]
-    span: Span,
-    kind: FormalParameterKind,
-    items: ElementsAndRest<'b, FormalParameter<'a>, SerFormalParameterRest<'a, 'b>>,
-}
-
 #[derive(Serialize)]
 #[serde(tag = "type", rename = "RestElement", rename_all = "camelCase")]
 struct SerFormalParameterRest<'a, 'b> {

napi/parser/test/__snapshots__/parse.test.ts.snap

@@ -0,0 +1,110 @@
+// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+exports[`parse > estree function params 1`] = `
+{
+  "async": true,
+  "body": {
+    "directives": [],
+    "end": 48,
+    "start": 46,
+    "statements": [],
+    "type": "FunctionBody",
+  },
+  "declare": false,
+  "end": 48,
+  "generator": false,
+  "id": {
+    "end": 19,
+    "name": "test",
+    "start": 15,
+    "type": "Identifier",
+  },
+  "params": [
+    {
+      "accessibility": null,
+      "decorators": [],
+      "end": 21,
+      "name": "x",
+      "optional": false,
+      "override": false,
+      "readonly": false,
+      "start": 20,
+      "type": "Identifier",
+      "typeAnnotation": null,
+    },
+    {
+      "accessibility": null,
+      "decorators": [],
+      "end": 28,
+      "optional": false,
+      "override": false,
+      "properties": [
+        {
+          "computed": false,
+          "end": 26,
+          "key": {
+            "end": 26,
+            "name": "y",
+            "start": 25,
+            "type": "Identifier",
+          },
+          "shorthand": true,
+          "start": 25,
+          "type": "BindingProperty",
+          "value": {
+            "end": 26,
+            "name": "y",
+            "optional": false,
+            "start": 25,
+            "type": "Identifier",
+            "typeAnnotation": null,
+          },
+        },
+      ],
+      "readonly": false,
+      "start": 23,
+      "type": "ObjectPattern",
+      "typeAnnotation": null,
+    },
+    {
+      "accessibility": null,
+      "decorators": [],
+      "elements": [
+        {
+          "end": 33,
+          "name": "z",
+          "optional": false,
+          "start": 32,
+          "type": "Identifier",
+          "typeAnnotation": null,
+        },
+      ],
+      "end": 35,
+      "optional": false,
+      "override": false,
+      "readonly": false,
+      "start": 30,
+      "type": "ArrayPattern",
+      "typeAnnotation": null,
+    },
+    {
+      "argument": {
+        "end": 44,
+        "name": "rest",
+        "start": 40,
+        "type": "Identifier",
+      },
+      "end": 44,
+      "optional": false,
+      "start": 37,
+      "type": "RestElement",
+      "typeAnnotation": null,
+    },
+  ],
+  "returnType": null,
+  "start": 0,
+  "thisParam": null,
+  "type": "FunctionDeclaration",
+  "typeParameters": null,
+}
+`;

napi/parser/test/parse.test.ts

@@ -26,6 +26,14 @@ describe('parse', () => {
     });
     expect(code.substring(comment.start, comment.end)).toBe('/*' + comment.value + '*/');
   });
+
+  it('estree function params', async () => {
+    const ret = await parseAsync(
+      'test.js',
+      `async function test(x, { y }, [ z ], ...rest) {}`,
+    );
+    expect(ret.program.body[0]).matchSnapshot();
+  });
 });
 
 describe('error', () => {

npm/oxc-types/types.d.ts

@@ -718,11 +718,13 @@ export interface Function extends Span {
   declare: boolean;
   typeParameters: TSTypeParameterDeclaration | null;
   thisParam: TSThisParameter | null;
-  params: FormalParameters;
+  params: ParamPattern[];
   returnType: TSTypeAnnotation | null;
   body: FunctionBody | null;
 }
 
+export type ParamPattern = FormalParameter | FormalParameterRest;
+
 export type FunctionType =
   | 'FunctionDeclaration'
   | 'FunctionExpression'
@@ -742,14 +744,15 @@ export interface FormalParameterRest extends Span {
   optional: boolean;
 }
 
-export interface FormalParameter extends Span {
-  type: 'FormalParameter';
-  decorators: Array<Decorator>;
-  pattern: BindingPattern;
-  accessibility: TSAccessibility | null;
-  readonly: boolean;
-  override: boolean;
-}
+export type FormalParameter =
+  & ({
+    decorators: Array<Decorator>;
+    accessibility: TSAccessibility | null;
+    readonly: boolean;
+    override: boolean;
+  })
+  & Span
+  & (BindingIdentifier | ObjectPattern | ArrayPattern | AssignmentPattern);
 
 export type FormalParameterKind = 'FormalParameter' | 'UniqueFormalParameters' | 'ArrowFormalParameters' | 'Signature';
 
@@ -764,7 +767,7 @@ export interface ArrowFunctionExpression extends Span {
   expression: boolean;
   async: boolean;
   typeParameters: TSTypeParameterDeclaration | null;
-  params: FormalParameters;
+  params: ParamPattern[];
   returnType: TSTypeAnnotation | null;
   body: FunctionBody;
 }
@@ -1532,7 +1535,7 @@ export interface TSCallSignatureDeclaration extends Span {
   type: 'TSCallSignatureDeclaration';
   typeParameters: TSTypeParameterDeclaration | null;
   thisParam: TSThisParameter | null;
-  params: FormalParameters;
+  params: ParamPattern[];
   returnType: TSTypeAnnotation | null;
 }
 
@@ -1546,14 +1549,14 @@ export interface TSMethodSignature extends Span {
   kind: TSMethodSignatureKind;
   typeParameters: TSTypeParameterDeclaration | null;
   thisParam: TSThisParameter | null;
-  params: FormalParameters;
+  params: ParamPattern[];
   returnType: TSTypeAnnotation | null;
 }
 
 export interface TSConstructSignatureDeclaration extends Span {
   type: 'TSConstructSignatureDeclaration';
   typeParameters: TSTypeParameterDeclaration | null;
-  params: FormalParameters;
+  params: ParamPattern[];
   returnType: TSTypeAnnotation | null;
 }
 
@@ -1642,15 +1645,15 @@ export interface TSFunctionType extends Span {
   type: 'TSFunctionType';
   typeParameters: TSTypeParameterDeclaration | null;
   thisParam: TSThisParameter | null;
-  params: FormalParameters;
+  params: ParamPattern[];
   returnType: TSTypeAnnotation;
 }
 
 export interface TSConstructorType extends Span {
   type: 'TSConstructorType';
   abstract: boolean;
   typeParameters: TSTypeParameterDeclaration | null;
-  params: FormalParameters;
+  params: ParamPattern[];
   returnType: TSTypeAnnotation;
 }