From 0674899b88859b91a1f304c3f27cd02de50d7bc0 Mon Sep 17 00:00:00 2001
From: Boshen <boshenc@gmail.com>
Date: Wed, 5 Apr 2023 14:36:37 +0800
Subject: [PATCH] Fuzz async (#257)

* fix(parser): parse `async(...null)` as call expression

relates #255

* fix(parser): parse `null?async():null`

relates #255
---
 crates/oxc_parser/src/js/function.rs | 26 +++++++++++++++++---------
 crates/oxc_parser/src/lib.rs         | 11 +++++++++--
 tasks/coverage/babel.snap            |  7 +++----
 tasks/coverage/typescript.snap       | 14 +++++++++++---
 4 files changed, 40 insertions(+), 18 deletions(-)

diff --git a/crates/oxc_parser/src/js/function.rs b/crates/oxc_parser/src/js/function.rs
index a94d33cad..14f095341 100644
--- a/crates/oxc_parser/src/js/function.rs
+++ b/crates/oxc_parser/src/js/function.rs
@@ -351,16 +351,24 @@ impl<'a> Parser<'a> {
             Kind::LParen => match self.nth_kind(offset + 1) {
                 // '()' is an arrow expression if followed by an '=>', a type annotation or body.
                 // Otherwise, a parenthesized expression with a missing inner expression
-                Kind::RParen
-                    if matches!(
-                        self.nth_kind(offset + 2),
-                        Kind::Arrow | Kind::Colon | Kind::LCurly
-                    ) =>
-                {
-                    IsParenthesizedArrowFunction::True
+                Kind::RParen => {
+                    let kind = self.nth_kind(offset + 2);
+                    if self.ts_enabled() && kind == Kind::Colon {
+                        IsParenthesizedArrowFunction::Maybe
+                    } else if matches!(kind, Kind::Arrow | Kind::LCurly) {
+                        IsParenthesizedArrowFunction::True
+                    } else {
+                        IsParenthesizedArrowFunction::False
+                    }
                 }
-                // Rest parameter '(...a' is certainly not a parenthesized expression
-                Kind::Dot3 => IsParenthesizedArrowFunction::True,
+                // Rest parameter
+                // '(...ident' is not a parenthesized expression
+                // '(...null' is a parenthesized expression
+                Kind::Dot3 => match self.nth_kind(offset + 1) {
+                    Kind::Ident => IsParenthesizedArrowFunction::True,
+                    kind if kind.is_literal() => IsParenthesizedArrowFunction::False,
+                    _ => IsParenthesizedArrowFunction::Maybe,
+                },
                 // '([ ...', '({ ... } can either be a parenthesized object or array expression or a destructing parameter
                 Kind::LBrack | Kind::LCurly => IsParenthesizedArrowFunction::Maybe,
                 _ if self.nth_kind(offset + 1).is_binding_identifier()
diff --git a/crates/oxc_parser/src/lib.rs b/crates/oxc_parser/src/lib.rs
index 748d151f9..be2b6408a 100644
--- a/crates/oxc_parser/src/lib.rs
+++ b/crates/oxc_parser/src/lib.rs
@@ -276,13 +276,20 @@ mod test {
         let allocator = Allocator::default();
         let source_type = SourceType::default();
 
-        let tests = [
+        let fail = [
             "1<(V=82<<t-j0<(V=$<LBI<(V=ut<I<(V=$<LBI<(V=uIV=82<<t-j0<(V=$<LBI<(V=ut<I<(V=$<LBI<(V<II>",
         ];
 
-        for source in tests {
+        for source in fail {
             let ret = Parser::new(&allocator, source, source_type).parse();
             assert!(!ret.errors.is_empty());
         }
+
+        let pass = ["async(...null)", "null?async():null", "switch(null){case async():}"];
+
+        for source in pass {
+            let ret = Parser::new(&allocator, source, source_type).parse();
+            assert!(ret.errors.is_empty());
+        }
     }
 }
diff --git a/tasks/coverage/babel.snap b/tasks/coverage/babel.snap
index c8f83e6f0..55ea47f62 100644
--- a/tasks/coverage/babel.snap
+++ b/tasks/coverage/babel.snap
@@ -3925,7 +3925,7 @@ Expect to Parse: "typescript/types/const-type-parameters/input.ts"
   × Unexpected token
    ╭─[es2015/uncategorised/286/input.js:1:1]
  1 │ (...[ 5 ]) => {}
-   ·       ─
+   ·  ───
    ╰────
 
   × Cannot assign to 'eval' in strict mode
@@ -6920,11 +6920,10 @@ Expect to Parse: "typescript/types/const-type-parameters/input.ts"
    ·     ───
    ╰────
 
-  × Expected `=>` but found `+`
+  × Unexpected token
    ╭─[esprima/es2015-arrow-function/rest-without-arrow/input.js:1:1]
  1 │ (...a) + 1
-   ·        ┬
-   ·        ╰── `=>` expected
+   ·  ───
    ╰────
 
   × Cannot assign to 'eval' in strict mode
diff --git a/tasks/coverage/typescript.snap b/tasks/coverage/typescript.snap
index 548fd2967..70cd778e9 100644
--- a/tasks/coverage/typescript.snap
+++ b/tasks/coverage/typescript.snap
@@ -9214,15 +9214,23 @@ Expect to Parse: "salsa/privateIdentifierExpando.ts"
  5 │ 
    ╰────
 
-  × Expected `=>` but found `{`
+  × Empty parenthesized expression
    ╭─[parser/ecmascript5/RegressionTests/parser509669.ts:1:1]
  1 │ function foo():any {
  2 │  return ():void {};
-   ·                 ┬
-   ·                 ╰── `=>` expected
+   ·          ▲
  3 │ }
    ╰────
 
+  × Expected a semicolon or an implicit semicolon after a statement, but found none
+   ╭─[parser/ecmascript5/RegressionTests/parser509669.ts:1:1]
+ 1 │ function foo():any {
+ 2 │  return ():void {};
+   ·           ▲
+ 3 │ }
+   ╰────
+  help: Try insert a semicolon here
+
   × Expected `}` but found `EOF`
    ╭─[parser/ecmascript5/RegressionTests/parser512084.ts:1:1]
  1 │ class foo {