void{} vs void() as a void initializer

Asked Oct 27 '17 at 16:16

Active Dec 14 '18 at 17:54

Viewed 111 times

The void() construction can be used to "create a value of the type void" (strange but true). But the C++11+ initialization syntax with curly braces doesn't work in such case:

int f_int_parenthesis()
{
    return int();  // OK
}

int f_int_braces()
{
    return int{};  // OK
}

void f_void_parenthesis()
{
    return void(); // OK
}

void f_void_braces()
{
    return void{}; // error
}

The code compilability is checked with g++ 7.2.0 and clang++ 3.8.0 (compilation flags are -std=c++14 -Wall -Wextra -Werror -pedantic-errors -O0).

Why is it so? Is it a standard-compliant behavior?

asked Oct 27 '17 at 16:16

Constructor

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[This might help](https://stackoverflow.com/questions/37701321/construction-of-a-void-type) the ambiguity of the `void` type .. – txtechhelp Oct 27 '17 at 16:38
@txtechhelp What do you mean? – Constructor Oct 27 '17 at 16:56
The answers explain a little more with links to the standard, essentially `void()` allows a type `void{}` does not, thus the error. – txtechhelp Oct 27 '17 at 17:34
[`void{}` is neither a valid type nor a valid expression](https://stackoverflow.com/questions/39354065/is-void-legal-or-not). – skypjack Oct 27 '17 at 20:01
1

`void{}` should be legal soon: https://stackoverflow.com/a/53267943/27678 – AndyG Dec 14 '18 at 18:56
@AndyG Excellent! :-) Thank you. – Constructor Dec 14 '18 at 19:06

void{} vs void() as a void initializer

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