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[Concurrency] async autoclosures are only legal on async functions. #33446

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Merged
merged 2 commits into from
Aug 13, 2020
Merged

[Concurrency] async autoclosures are only legal on async functions. #33446

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a535463
[Concurrency] async autoclosures are only legal on async functions.
DougGregor Aug 13, 2020
eda621f
[Concurrency] Only suggest adding 'async' to functions.
DougGregor Aug 13, 2020
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32 changes: 19 additions & 13 deletions include/swift/AST/DiagnosticsSema.def
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Original file line number Diff line number Diff line change
Expand Up @@ -2174,9 +2174,6 @@ NOTE(protocol_witness_settable_conflict,none,
"candidate is not settable, but protocol requires it", ())
NOTE(protocol_witness_rethrows_conflict,none,
"candidate is not 'rethrows', but protocol requires it", ())
NOTE(protocol_witness_async_conflict,none,
"candidate is %select{not |}0'async', but protocol requirement is%select{| not}0",
(bool))
NOTE(protocol_witness_throws_conflict,none,
"candidate throws, but protocol does not allow it", ())
NOTE(protocol_witness_not_objc,none,
Expand Down Expand Up @@ -4036,6 +4033,16 @@ NOTE(note_error_to_optional,none,
"did you mean to handle error as optional value?", ())
NOTE(note_disable_error_propagation,none,
"did you mean to disable error propagation?", ())

WARNING(no_throw_in_try,none,
"no calls to throwing functions occur within 'try' expression", ())

WARNING(no_throw_in_do_with_catch,none,
"'catch' block is unreachable because no errors are thrown in 'do' block", ())

//------------------------------------------------------------------------------
// MARK: Concurrency
//------------------------------------------------------------------------------
ERROR(async_call_without_await,none,
"call is 'async' but is not marked with 'await'", ())
ERROR(async_call_without_await_in_autoclosure,none,
Expand All @@ -4056,12 +4063,15 @@ ERROR(async_in_nonasync_function,none,
(bool, bool))
NOTE(note_add_async_to_function,none,
"add 'async' to function %0 to make it asynchronous", (DeclName))

WARNING(no_throw_in_try,none,
"no calls to throwing functions occur within 'try' expression", ())

WARNING(no_throw_in_do_with_catch,none,
"'catch' block is unreachable because no errors are thrown in 'do' block", ())
ERROR(not_objc_function_async,none,
"'async' function cannot be represented in Objective-C", ())
NOTE(not_objc_function_type_async,none,
"'async' function types cannot be represented in Objective-C", ())
NOTE(protocol_witness_async_conflict,none,
"candidate is %select{not |}0'async', but protocol requirement is%select{| not}0",
(bool))
ERROR(async_autoclosure_nonasync_function,none,
"'async' autoclosure parameter in a non-'async' function", ())

//------------------------------------------------------------------------------
// MARK: Type Check Types
Expand Down Expand Up @@ -4417,10 +4427,6 @@ NOTE(not_objc_generic_type_param,none,
NOTE(not_objc_function_type_param,none,
"function types cannot be represented in Objective-C unless their "
"parameters and returns can be", ())
ERROR(not_objc_function_async,none,
"'async' function cannot be represented in Objective-C", ())
NOTE(not_objc_function_type_async,none,
"'async' function types cannot be represented in Objective-C", ())
NOTE(not_objc_function_type_throwing,none,
"throwing function types cannot be represented in Objective-C", ())
NOTE(objc_inferring_on_objc_protocol_member,none,
Expand Down
15 changes: 14 additions & 1 deletion lib/Sema/TypeCheckDecl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2148,9 +2148,22 @@ static Type validateParameterType(ParamDecl *decl) {
decl->setInvalid();
return ErrorType::get(ctx);
}
}

return Ty;
// async autoclosures can only occur as parameters to async functions.
if (decl->isAutoClosure()) {
if (auto fnType = Ty->getAs<FunctionType>()) {
if (fnType->isAsync() &&
!(isa<AbstractFunctionDecl>(dc) &&
cast<AbstractFunctionDecl>(dc)->hasAsync())) {
decl->diagnose(diag::async_autoclosure_nonasync_function);
if (auto func = dyn_cast<FuncDecl>(dc)) {
func->diagnose(diag::note_add_async_to_function, func->getName());
}
}
}
}

return Ty;
}

Expand Down
23 changes: 15 additions & 8 deletions test/expr/unary/async_await.swift
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Expand Up @@ -33,20 +33,27 @@ struct SomeStruct {
static var y = __await getInt() // expected-error{{'async' call cannot occur in a global variable initializer}}
}

func acceptAutoclosureNonAsync(_: @autoclosure () -> Int) { }
func acceptAutoclosureAsync(_: @autoclosure () async -> Int) { }
func acceptAutoclosureNonAsync(_: @autoclosure () -> Int) async { }
func acceptAutoclosureAsync(_: @autoclosure () async -> Int) async { }

func acceptAutoclosureNonAsyncBad(_: @autoclosure () async -> Int) { }
// expected-error@-1{{'async' autoclosure parameter in a non-'async' function}}
// expected-note@-2{{add 'async' to function 'acceptAutoclosureNonAsyncBad' to make it asynchronous}}

struct HasAsyncBad {
init(_: @autoclosure () async -> Int) { }
// expected-error@-1{{'async' autoclosure parameter in a non-'async' function}}
}

func testAutoclosure() async {
acceptAutoclosureAsync(getInt()) // expected-error{{call is 'async' in an autoclosure argument is not marked with 'await'}}
acceptAutoclosureNonAsync(getInt()) // expected-error{{'async' in an autoclosure that does not support concurrency}}
__await acceptAutoclosureAsync(getInt()) // expected-error{{call is 'async' in an autoclosure argument is not marked with 'await'}}
__await acceptAutoclosureNonAsync(getInt()) // expected-error{{'async' in an autoclosure that does not support concurrency}}

acceptAutoclosureAsync(__await getInt())
acceptAutoclosureNonAsync(__await getInt()) // expected-error{{'async' in an autoclosure that does not support concurrency}}
__await acceptAutoclosureAsync(__await getInt())
__await acceptAutoclosureNonAsync(__await getInt()) // expected-error{{'async' in an autoclosure that does not support concurrency}}

__await acceptAutoclosureAsync(getInt()) // expected-error{{call is 'async' in an autoclosure argument is not marked with 'await'}}
// expected-warning@-1{{no calls to 'async' functions occur within 'await' expression}}
__await acceptAutoclosureNonAsync(getInt()) // expected-error{{'async' in an autoclosure that does not support concurrency}}
// expected-warning@-1{{no calls to 'async' functions occur within 'await' expression}}
}

// Test inference of 'async' from the body of a closure.
Expand Down