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warn when generator function without any yield expression (#13847) #19413

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9 changes: 7 additions & 2 deletions src/compiler/checker.ts
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Expand Up @@ -17283,7 +17283,12 @@ namespace ts {
else {
let types: Type[];
if (functionFlags & FunctionFlags.Generator) { // Generator or AsyncGenerator function
types = concatenate(checkAndAggregateYieldOperandTypes(func, checkMode), checkAndAggregateReturnExpressionTypes(func, checkMode));
const aggregatedYield = checkAndAggregateYieldOperandTypes(func, checkMode);
const aggregatedReturn = checkAndAggregateReturnExpressionTypes(func, checkMode)
if (aggregatedReturn.length && aggregatedYield.length === 0) {
error(func, Diagnostics.A_generator_cannot_have_a_return_statement_and_no_yield_statements);
}
types = concatenate(aggregatedYield, aggregatedReturn);
if (!types || types.length === 0) {
const iterableIteratorAny = functionFlags & FunctionFlags.Async
? createAsyncIterableIteratorType(anyType) // AsyncGenerator function
Expand Down Expand Up @@ -25071,7 +25076,7 @@ namespace ts {
if (isInAmbientContext(node)) {
return grammarErrorOnNode(node.asteriskToken, Diagnostics.Generators_are_not_allowed_in_an_ambient_context);
}
if (!node.body) {
else {
return grammarErrorOnNode(node.asteriskToken, Diagnostics.An_overload_signature_cannot_be_declared_as_a_generator);
}
}
Expand Down
4 changes: 4 additions & 0 deletions src/compiler/diagnosticMessages.json
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Expand Up @@ -911,6 +911,10 @@
"category": "Error",
"code": 1329
},
"A generator cannot have a return statement and no yield statements.": {
"category": "Error",
"code": 1330
},

"Duplicate identifier '{0}'.": {
"category": "Error",
Expand Down
2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.classMethods.es2015.js
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Expand Up @@ -38,7 +38,6 @@ class C6 {
//// [C7.ts]
class C7 {
async * f() {
return 1;
}
}
//// [C8.ts]
Expand Down Expand Up @@ -215,7 +214,6 @@ var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _ar
class C7 {
f() {
return __asyncGenerator(this, arguments, function* f_1() {
return 1;
});
}
}
Expand Down
2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.classMethods.es2015.symbols
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Expand Up @@ -67,8 +67,6 @@ class C7 {

async * f() {
>f : Symbol(C7.f, Decl(C7.ts, 0, 10))

return 1;
}
}
=== tests/cases/conformance/emitter/es2015/asyncGenerators/C8.ts ===
Expand Down
5 changes: 1 addition & 4 deletions tests/baselines/reference/emitter.asyncGenerators.classMethods.es2015.types
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Expand Up @@ -80,10 +80,7 @@ class C7 {
>C7 : C7

async * f() {
>f : () => AsyncIterableIterator<1>

return 1;
>1 : 1
>f : () => AsyncIterableIterator<any>
}
}
=== tests/cases/conformance/emitter/es2015/asyncGenerators/C8.ts ===
Expand Down
3 changes: 1 addition & 2 deletions tests/baselines/reference/emitter.asyncGenerators.classMethods.es5.js
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Expand Up @@ -38,7 +38,6 @@ class C6 {
//// [C7.ts]
class C7 {
async * f() {
return 1;
}
}
//// [C8.ts]
Expand Down Expand Up @@ -497,7 +496,7 @@ var C7 = /** @class */ (function () {
C7.prototype.f = function () {
return __asyncGenerator(this, arguments, function f_1() {
return __generator(this, function (_a) {
return [2 /*return*/, 1];
return [2 /*return*/];
});
});
};
Expand Down
2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.classMethods.es5.symbols
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Expand Up @@ -67,8 +67,6 @@ class C7 {

async * f() {
>f : Symbol(C7.f, Decl(C7.ts, 0, 10))

return 1;
}
}
=== tests/cases/conformance/emitter/es5/asyncGenerators/C8.ts ===
Expand Down
5 changes: 1 addition & 4 deletions tests/baselines/reference/emitter.asyncGenerators.classMethods.es5.types
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Expand Up @@ -80,10 +80,7 @@ class C7 {
>C7 : C7

async * f() {
>f : () => AsyncIterableIterator<1>

return 1;
>1 : 1
>f : () => AsyncIterableIterator<any>
}
}
=== tests/cases/conformance/emitter/es5/asyncGenerators/C8.ts ===
Expand Down
2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.classMethods.esnext.js
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Expand Up @@ -38,7 +38,6 @@ class C6 {
//// [C7.ts]
class C7 {
async * f() {
return 1;
}
}
//// [C8.ts]
Expand Down Expand Up @@ -98,7 +97,6 @@ class C6 {
//// [C7.js]
class C7 {
async *f() {
return 1;
}
}
//// [C8.js]
Expand Down
2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.classMethods.esnext.symbols
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Expand Up @@ -67,8 +67,6 @@ class C7 {

async * f() {
>f : Symbol(C7.f, Decl(C7.ts, 0, 10))

return 1;
}
}
=== tests/cases/conformance/emitter/esnext/asyncGenerators/C8.ts ===
Expand Down
5 changes: 1 addition & 4 deletions tests/baselines/reference/emitter.asyncGenerators.classMethods.esnext.types
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Expand Up @@ -80,10 +80,7 @@ class C7 {
>C7 : C7

async * f() {
>f : () => AsyncIterableIterator<1>

return 1;
>1 : 1
>f : () => AsyncIterableIterator<any>
}
}
=== tests/cases/conformance/emitter/esnext/asyncGenerators/C8.ts ===
Expand Down
2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es2015.js
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Expand Up @@ -25,7 +25,6 @@ async function * f6() {
}
//// [F7.ts]
async function * f7() {
return 1;
}


Expand Down Expand Up @@ -171,6 +170,5 @@ var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _ar
};
function f7() {
return __asyncGenerator(this, arguments, function* f7_1() {
return 1;
});
}
2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es2015.symbols
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Expand Up @@ -40,7 +40,5 @@ async function * f6() {
=== tests/cases/conformance/emitter/es2015/asyncGenerators/F7.ts ===
async function * f7() {
>f7 : Symbol(f7, Decl(F7.ts, 0, 0))

return 1;
}

5 changes: 1 addition & 4 deletions tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es2015.types
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Expand Up @@ -53,9 +53,6 @@ async function * f6() {
}
=== tests/cases/conformance/emitter/es2015/asyncGenerators/F7.ts ===
async function * f7() {
>f7 : () => AsyncIterableIterator<1>

return 1;
>1 : 1
>f7 : () => AsyncIterableIterator<any>
}

3 changes: 1 addition & 2 deletions tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es5.js
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Expand Up @@ -25,7 +25,6 @@ async function * f6() {
}
//// [F7.ts]
async function * f7() {
return 1;
}


Expand Down Expand Up @@ -433,7 +432,7 @@ var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _ar
function f7() {
return __asyncGenerator(this, arguments, function f7_1() {
return __generator(this, function (_a) {
return [2 /*return*/, 1];
return [2 /*return*/];
});
});
}
2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es5.symbols
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Expand Up @@ -40,7 +40,5 @@ async function * f6() {
=== tests/cases/conformance/emitter/es5/asyncGenerators/F7.ts ===
async function * f7() {
>f7 : Symbol(f7, Decl(F7.ts, 0, 0))

return 1;
}

5 changes: 1 addition & 4 deletions tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es5.types
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Expand Up @@ -53,9 +53,6 @@ async function * f6() {
}
=== tests/cases/conformance/emitter/es5/asyncGenerators/F7.ts ===
async function * f7() {
>f7 : () => AsyncIterableIterator<1>

return 1;
>1 : 1
>f7 : () => AsyncIterableIterator<any>
}

2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.esnext.js
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Expand Up @@ -25,7 +25,6 @@ async function * f6() {
}
//// [F7.ts]
async function * f7() {
return 1;
}


Expand Down Expand Up @@ -54,5 +53,4 @@ async function* f6() {
}
//// [F7.js]
async function* f7() {
return 1;
}
2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.esnext.symbols
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Expand Up @@ -40,7 +40,5 @@ async function * f6() {
=== tests/cases/conformance/emitter/esnext/asyncGenerators/F7.ts ===
async function * f7() {
>f7 : Symbol(f7, Decl(F7.ts, 0, 0))

return 1;
}

5 changes: 1 addition & 4 deletions tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.esnext.types
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Expand Up @@ -53,9 +53,6 @@ async function * f6() {
}
=== tests/cases/conformance/emitter/esnext/asyncGenerators/F7.ts ===
async function * f7() {
>f7 : () => AsyncIterableIterator<1>

return 1;
>1 : 1
>f7 : () => AsyncIterableIterator<any>
}

2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es2015.js
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Expand Up @@ -25,7 +25,6 @@ const f6 = async function * () {
}
//// [F7.ts]
const f7 = async function * () {
return 1;
}


Expand Down Expand Up @@ -171,6 +170,5 @@ var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _ar
};
const f7 = function () {
return __asyncGenerator(this, arguments, function* () {
return 1;
});
};
2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es2015.symbols
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Expand Up @@ -40,7 +40,5 @@ const f6 = async function * () {
=== tests/cases/conformance/emitter/es2015/asyncGenerators/F7.ts ===
const f7 = async function * () {
>f7 : Symbol(f7, Decl(F7.ts, 0, 5))

return 1;
}

7 changes: 2 additions & 5 deletions tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es2015.types
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Expand Up @@ -59,10 +59,7 @@ const f6 = async function * () {
}
=== tests/cases/conformance/emitter/es2015/asyncGenerators/F7.ts ===
const f7 = async function * () {
>f7 : () => AsyncIterableIterator<1>
>async function * () { return 1;} : () => AsyncIterableIterator<1>

return 1;
>1 : 1
>f7 : () => AsyncIterableIterator<any>
>async function * () {} : () => AsyncIterableIterator<any>
}

3 changes: 1 addition & 2 deletions tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es5.js
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Expand Up @@ -25,7 +25,6 @@ const f6 = async function * () {
}
//// [F7.ts]
const f7 = async function * () {
return 1;
}


Expand Down Expand Up @@ -433,7 +432,7 @@ var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _ar
var f7 = function () {
return __asyncGenerator(this, arguments, function () {
return __generator(this, function (_a) {
return [2 /*return*/, 1];
return [2 /*return*/];
});
});
};
2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es5.symbols
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Expand Up @@ -40,7 +40,5 @@ const f6 = async function * () {
=== tests/cases/conformance/emitter/es5/asyncGenerators/F7.ts ===
const f7 = async function * () {
>f7 : Symbol(f7, Decl(F7.ts, 0, 5))

return 1;
}

7 changes: 2 additions & 5 deletions tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es5.types
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Expand Up @@ -59,10 +59,7 @@ const f6 = async function * () {
}
=== tests/cases/conformance/emitter/es5/asyncGenerators/F7.ts ===
const f7 = async function * () {
>f7 : () => AsyncIterableIterator<1>
>async function * () { return 1;} : () => AsyncIterableIterator<1>

return 1;
>1 : 1
>f7 : () => AsyncIterableIterator<any>
>async function * () {} : () => AsyncIterableIterator<any>
}

2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.functionExpressions.esnext.js
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Expand Up @@ -25,7 +25,6 @@ const f6 = async function * () {
}
//// [F7.ts]
const f7 = async function * () {
return 1;
}


Expand Down Expand Up @@ -54,5 +53,4 @@ const f6 = async function* () {
};
//// [F7.js]
const f7 = async function* () {
return 1;
};
2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.functionExpressions.esnext.symbols
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Expand Up @@ -40,7 +40,5 @@ const f6 = async function * () {
=== tests/cases/conformance/emitter/esnext/asyncGenerators/F7.ts ===
const f7 = async function * () {
>f7 : Symbol(f7, Decl(F7.ts, 0, 5))

return 1;
}

7 changes: 2 additions & 5 deletions tests/baselines/reference/emitter.asyncGenerators.functionExpressions.esnext.types
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Expand Up @@ -59,10 +59,7 @@ const f6 = async function * () {
}
=== tests/cases/conformance/emitter/esnext/asyncGenerators/F7.ts ===
const f7 = async function * () {
>f7 : () => AsyncIterableIterator<1>
>async function * () { return 1;} : () => AsyncIterableIterator<1>

return 1;
>1 : 1
>f7 : () => AsyncIterableIterator<any>
>async function * () {} : () => AsyncIterableIterator<any>
}

2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.objectLiteralMethods.es2015.js
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Expand Up @@ -38,7 +38,6 @@ const o6 = {
//// [O7.ts]
const o7 = {
async * f() {
return 1;
}
}

Expand Down Expand Up @@ -198,7 +197,6 @@ var __asyncGenerator = (this && this.__asyncGenerator) || function (thisArg, _ar
const o7 = {
f() {
return __asyncGenerator(this, arguments, function* f_1() {
return 1;
});
}
};
2 changes: 0 additions & 2 deletions tests/baselines/reference/emitter.asyncGenerators.objectLiteralMethods.es2015.symbols
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Expand Up @@ -67,8 +67,6 @@ const o7 = {

async * f() {
>f : Symbol(f, Decl(O7.ts, 0, 12))

return 1;
}
}

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