Re: C23 auto x C++ auto.

Em 5/26/2024 12:03 PM, Thiago Adams escreveu:

Em 5/26/2024 11:23 AM, Michael S escreveu:

On Sun, 26 May 2024 10:49:30 -0300
Thiago Adams <thiago.adams@gmail.com> wrote:
>

I think most people is not aware of this:
>
  From 3096 C23 draft
>
"
6.7.9 Type inference
...
   2 For such a declaration that is the definition of an object the
init- declarator shall have the form
>
     direct-declarator = assignment-expression
"
>
Basically "direct-declarator" differs from "declarator" because it
does not contains pointer.
>
Then the type inference using auto and pointer is something undefined
in C23.
>
struct node{
      struct node * next;
>
};
int main(){
     struct node node = {};
     auto * p = node.next;
}
>
<source>:7:4: error: 'auto' requires a plain identifier, possibly
with attributes, as declarator
      7 |    auto * p = node.next;
        |    ^~~~
>
This differs from C++.
>
>

>
Differs in positive way. Less confusing.
>

I agree!
 

clang still accepts it.
https://godbolt.org/z/nxhcWGo5h
"For such a declaration that is the definition of an object the init-declarator shall have the form
direct-declarator = assignment-expression
..
177) Implementations need not accept a direct declarator that is not of the form
   identifier attribute-specifier-sequence opt
optionally enclosed in balanced pairs of parentheses;
if a direct declarator of a different form is accepted, the behavior is implementation-defined.
"