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Oleksandr Tarasiuk (a-tarasyuk) wants to merge 5 commits into
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fix(64231): avoid parsing async() calls as typed arrows in conditionals #64233

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a1110c5
fix async and yield parsing
a-tarasyuk Oct 17, 2026
f7389f8
Merge branch 'main' into fix/64231
a-tarasyuk Oct 18, 2026
8a8315d
separate expression parsing flags
a-tarasyuk Oct 18, 2026
ecdf5be
Merge branch 'main' of https://github.com/microsoft/TypeScript into f…
a-tarasyuk Oct 18, 2026
9021186
Merge branch 'fix/64231' of https://github.com/a-tarasyuk/TypeScript …
a-tarasyuk Oct 18, 2026
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111 changes: 68 additions & 43 deletions tsc/internal/parser/parser.go
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455 changes: 455 additions & 0 deletions tsc/internal/parser/parser_test.go
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8 changes: 8 additions & 0 deletions tsc/internal/parser/types.go
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Original file line number Diff line number Diff line change
Expand Up @@ -12,3 +12,11 @@ const (
ParseFlagsIgnoreMissingOpenBrace ParseFlags = 1 << 4
ParseFlagsJSDoc ParseFlags = 1 << 5
)

type ExpressionParseFlags uint32

const (
ExpressionParseFlagsNone ExpressionParseFlags = 0
ExpressionParseFlagsDisallowArrowReturnType ExpressionParseFlags = 1 << 0
ExpressionParseFlagsAllowAmbiguousAsyncArrow ExpressionParseFlags = 1 << 1
)
79 changes: 79 additions & 0 deletions tsc/testdata/baselines/reference/compiler/parenthesizedAsyncArrowFunction.js
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,49 @@
// Repro from #20096

let foo = (async bar => bar);

const a = true;
const b = 1;
const c = [b];

function async(...c: number[]): number {
return b;
}

const f1 = a ? async() : 0;
const f2 = a ? async() : x => x;
const f3 = a ? a ? async() : 0 : b;
const f4 = a ? x => async() : x => x;
const f5 = a ? async (): Promise<number> => b : () => b;
const f6 = a ? async (): Promise<number> => { return b; } : () => b;
const f7 = a ? async (): Promise<number> => a ? async() : 0 : () => b;
const f8 = a ? (): number => b : () => b;

const f9 = a ? async(...c) : 0;
const f10 = a ? async(...c) : x => x;
const f11 = a ? async (...c: number[]): Promise<number> => c.length : () => 0;
const f12 = a ? async() : x => async (...c): Promise<number> => c.length;

type T = Promise<number>;
const f13 = a ? async() : x => async (): Promise<number> => b;
const f14 = a ? async() : x => async (): T => 0;
const f15 = a ? (b) : x => async (): T => 0;
const f16 = a ? async(...c) : x => async (): T => 0;
const f17 = a ? async() : x => (y): number => y;
const f18 = a ? async() : x => async <U>(): T => 0;
const f19 = a ? async(...c) : x => (y): number => y;
const f20 = a ? async(...c) : x => async <U>(): T => 0;
const f21 = a ? (x): number => (b): T => 0;
const f22 = a ? async <U>(): Promise<number> => (b): T => 0;
const f23 = a ? async () => async() : x => x;
const f24 = a ? async (...c) => async() : x => x;
const f25 = a ? () => async() : x => x;
const f26 = a ? async (c: number): Promise<number> => async() : x => x;

function* g() {
const f1 = a ? yield async(...c) : 0;
const f2 = a ? yield async(...c) : x => x;
}


//// [parenthesizedAsyncArrowFunction.js]
Expand All @@ -19,3 +62,39 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
});
};
let foo = ((bar) => __awaiter(void 0, void 0, void 0, function* () { return bar; }));
const a = true;
const b = 1;
const c = [b];
function async(...c) {
return b;
}
const f1 = a ? async() : 0;
const f2 = a ? async() : x => x;
const f3 = a ? a ? async() : 0 : b;
const f4 = a ? x => async() : x => x;
const f5 = a ? () => __awaiter(void 0, void 0, void 0, function* () { return b; }) : () => b;
const f6 = a ? () => __awaiter(void 0, void 0, void 0, function* () { return b; }) : () => b;
const f7 = a ? () => __awaiter(void 0, void 0, void 0, function* () { return a ? async() : 0; }) : () => b;
const f8 = a ? () => b : () => b;
const f9 = a ? async(...c) : 0;
const f10 = a ? async(...c) : x => x;
const f11 = a ? (...c) => __awaiter(void 0, void 0, void 0, function* () { return c.length; }) : () => 0;
const f12 = a ? async() : x => (...c) => __awaiter(void 0, void 0, void 0, function* () { return c.length; });
const f13 = a ? async() : x => () => __awaiter(void 0, void 0, void 0, function* () { return b; });
const f14 = a ? async() : x => () => __awaiter(void 0, void 0, void 0, function* () { return 0; });
const f15 = a ? (b) : x => () => __awaiter(void 0, void 0, void 0, function* () { return 0; });
const f16 = a ? async(...c) : x => () => __awaiter(void 0, void 0, void 0, function* () { return 0; });
const f17 = a ? async() : x => (y) => y;
const f18 = a ? async() : x => () => __awaiter(void 0, void 0, void 0, function* () { return 0; });
const f19 = a ? async(...c) : x => (y) => y;
const f20 = a ? async(...c) : x => () => __awaiter(void 0, void 0, void 0, function* () { return 0; });
const f21 = a ? (x) => (b) : T => 0;
const f22 = a ? () => __awaiter(void 0, void 0, void 0, function* () { return (b); }) : T => 0;
const f23 = a ? () => __awaiter(void 0, void 0, void 0, function* () { return async(); }) : x => x;
const f24 = a ? (...c) => __awaiter(void 0, void 0, void 0, function* () { return async(); }) : x => x;
const f25 = a ? () => async() : x => x;
const f26 = a ? (c) => __awaiter(void 0, void 0, void 0, function* () { return async(); }) : x => x;
function* g() {
const f1 = a ? yield async(...c) : 0;
const f2 = a ? yield async(...c) : x => x;
}
239 changes: 239 additions & 0 deletions tsc/testdata/baselines/reference/compiler/parenthesizedAsyncArrowFunction.symbols
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Expand Up @@ -8,3 +8,242 @@ let foo = (async bar => bar);
>bar : Symbol(bar, Decl(parenthesizedAsyncArrowFunction.ts, 2, 16))
>bar : Symbol(bar, Decl(parenthesizedAsyncArrowFunction.ts, 2, 16))

const a = true;
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))

const b = 1;
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))

const c = [b];
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 6, 5))
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))

function async(...c: number[]): number {
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 8, 15))

return b;
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))
}

const f1 = a ? async() : 0;
>f1 : Symbol(f1, Decl(parenthesizedAsyncArrowFunction.ts, 12, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))

const f2 = a ? async() : x => x;
>f2 : Symbol(f2, Decl(parenthesizedAsyncArrowFunction.ts, 13, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 13, 24))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 13, 24))

const f3 = a ? a ? async() : 0 : b;
>f3 : Symbol(f3, Decl(parenthesizedAsyncArrowFunction.ts, 14, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))

const f4 = a ? x => async() : x => x;
>f4 : Symbol(f4, Decl(parenthesizedAsyncArrowFunction.ts, 15, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 15, 14))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 15, 29))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 15, 29))

const f5 = a ? async (): Promise<number> => b : () => b;
>f5 : Symbol(f5, Decl(parenthesizedAsyncArrowFunction.ts, 16, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))

const f6 = a ? async (): Promise<number> => { return b; } : () => b;
>f6 : Symbol(f6, Decl(parenthesizedAsyncArrowFunction.ts, 17, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))

const f7 = a ? async (): Promise<number> => a ? async() : 0 : () => b;
>f7 : Symbol(f7, Decl(parenthesizedAsyncArrowFunction.ts, 18, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))

const f8 = a ? (): number => b : () => b;
>f8 : Symbol(f8, Decl(parenthesizedAsyncArrowFunction.ts, 19, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))

const f9 = a ? async(...c) : 0;
>f9 : Symbol(f9, Decl(parenthesizedAsyncArrowFunction.ts, 21, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 6, 5))

const f10 = a ? async(...c) : x => x;
>f10 : Symbol(f10, Decl(parenthesizedAsyncArrowFunction.ts, 22, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 6, 5))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 22, 29))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 22, 29))

const f11 = a ? async (...c: number[]): Promise<number> => c.length : () => 0;
>f11 : Symbol(f11, Decl(parenthesizedAsyncArrowFunction.ts, 23, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 23, 23))
>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
>c.length : Symbol(Array.length, Decl(lib.es5.d.ts, --, --))
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 23, 23))
>length : Symbol(Array.length, Decl(lib.es5.d.ts, --, --))

const f12 = a ? async() : x => async (...c): Promise<number> => c.length;
>f12 : Symbol(f12, Decl(parenthesizedAsyncArrowFunction.ts, 24, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 24, 25))
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 24, 38))
>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
>c.length : Symbol(Array.length, Decl(lib.es5.d.ts, --, --))
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 24, 38))
>length : Symbol(Array.length, Decl(lib.es5.d.ts, --, --))

type T = Promise<number>;
>T : Symbol(T, Decl(parenthesizedAsyncArrowFunction.ts, 24, 73))
>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))

const f13 = a ? async() : x => async (): Promise<number> => b;
>f13 : Symbol(f13, Decl(parenthesizedAsyncArrowFunction.ts, 27, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 27, 25))
>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))

const f14 = a ? async() : x => async (): T => 0;
>f14 : Symbol(f14, Decl(parenthesizedAsyncArrowFunction.ts, 28, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 28, 25))
>T : Symbol(T, Decl(parenthesizedAsyncArrowFunction.ts, 24, 73))

const f15 = a ? (b) : x => async (): T => 0;
>f15 : Symbol(f15, Decl(parenthesizedAsyncArrowFunction.ts, 29, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 29, 21))
>T : Symbol(T, Decl(parenthesizedAsyncArrowFunction.ts, 24, 73))

const f16 = a ? async(...c) : x => async (): T => 0;
>f16 : Symbol(f16, Decl(parenthesizedAsyncArrowFunction.ts, 30, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 6, 5))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 30, 29))
>T : Symbol(T, Decl(parenthesizedAsyncArrowFunction.ts, 24, 73))

const f17 = a ? async() : x => (y): number => y;
>f17 : Symbol(f17, Decl(parenthesizedAsyncArrowFunction.ts, 31, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 31, 25))
>y : Symbol(y, Decl(parenthesizedAsyncArrowFunction.ts, 31, 32))
>y : Symbol(y, Decl(parenthesizedAsyncArrowFunction.ts, 31, 32))

const f18 = a ? async() : x => async <U>(): T => 0;
>f18 : Symbol(f18, Decl(parenthesizedAsyncArrowFunction.ts, 32, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 32, 25))
>U : Symbol(U, Decl(parenthesizedAsyncArrowFunction.ts, 32, 38))
>T : Symbol(T, Decl(parenthesizedAsyncArrowFunction.ts, 24, 73))

const f19 = a ? async(...c) : x => (y): number => y;
>f19 : Symbol(f19, Decl(parenthesizedAsyncArrowFunction.ts, 33, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 6, 5))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 33, 29))
>y : Symbol(y, Decl(parenthesizedAsyncArrowFunction.ts, 33, 36))
>y : Symbol(y, Decl(parenthesizedAsyncArrowFunction.ts, 33, 36))

const f20 = a ? async(...c) : x => async <U>(): T => 0;
>f20 : Symbol(f20, Decl(parenthesizedAsyncArrowFunction.ts, 34, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 6, 5))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 34, 29))
>U : Symbol(U, Decl(parenthesizedAsyncArrowFunction.ts, 34, 42))
>T : Symbol(T, Decl(parenthesizedAsyncArrowFunction.ts, 24, 73))

const f21 = a ? (x): number => (b): T => 0;
>f21 : Symbol(f21, Decl(parenthesizedAsyncArrowFunction.ts, 35, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 35, 17))
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))
>T : Symbol(T, Decl(parenthesizedAsyncArrowFunction.ts, 35, 35))

const f22 = a ? async <U>(): Promise<number> => (b): T => 0;
>f22 : Symbol(f22, Decl(parenthesizedAsyncArrowFunction.ts, 36, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>U : Symbol(U, Decl(parenthesizedAsyncArrowFunction.ts, 36, 23))
>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
>b : Symbol(b, Decl(parenthesizedAsyncArrowFunction.ts, 5, 5))
>T : Symbol(T, Decl(parenthesizedAsyncArrowFunction.ts, 36, 52))

const f23 = a ? async () => async() : x => x;
>f23 : Symbol(f23, Decl(parenthesizedAsyncArrowFunction.ts, 37, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 37, 37))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 37, 37))

const f24 = a ? async (...c) => async() : x => x;
>f24 : Symbol(f24, Decl(parenthesizedAsyncArrowFunction.ts, 38, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 38, 23))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 38, 41))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 38, 41))

const f25 = a ? () => async() : x => x;
>f25 : Symbol(f25, Decl(parenthesizedAsyncArrowFunction.ts, 39, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 39, 31))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 39, 31))

const f26 = a ? async (c: number): Promise<number> => async() : x => x;
>f26 : Symbol(f26, Decl(parenthesizedAsyncArrowFunction.ts, 40, 5))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 40, 23))
>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 40, 63))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 40, 63))

function* g() {
>g : Symbol(g, Decl(parenthesizedAsyncArrowFunction.ts, 40, 71))

const f1 = a ? yield async(...c) : 0;
>f1 : Symbol(f1, Decl(parenthesizedAsyncArrowFunction.ts, 43, 9))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 6, 5))

const f2 = a ? yield async(...c) : x => x;
>f2 : Symbol(f2, Decl(parenthesizedAsyncArrowFunction.ts, 44, 9))
>a : Symbol(a, Decl(parenthesizedAsyncArrowFunction.ts, 4, 5))
>async : Symbol(async, Decl(parenthesizedAsyncArrowFunction.ts, 6, 14))
>c : Symbol(c, Decl(parenthesizedAsyncArrowFunction.ts, 6, 5))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 44, 38))
>x : Symbol(x, Decl(parenthesizedAsyncArrowFunction.ts, 44, 38))
}

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