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Re: Usage of static in array declaration

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On 9/10/2021 7:38 AM, Thiago Adams wrote:
> 
> It is not clear to me  why this static was created and
> what is the behavior.

I think it is pretty clearly explained in the standard and elsewhere: to 
help the compiler to optimize the code.

> For instance,
> void F(char name[static 10]){
> }
> 
> Can I pass a pointer to char*?

Of course. The parameter type is still `char *`. What prompted the question?

> I will check some compilers to see what is the actual behavior
> 
> gcc 11.2
> 
> void f(char name[static 10]){}
> 
> int main()
> {
>   char *p = "abc";
>   f(p);
> }
> gives me the same warning with our without static.
> 
>   warning: 'f' accessing 10 bytes in a region of size 4 [-Wstringop-overflow=]
> 
> no warning here
> 
> void f(char name[static 10]){}
> 
> extern char* s1;
> int main()
> {
>   f(s1);
> }
> 

For obvious reasons, the compiler was "smart enough" to issue the 
warning in the first case. In the second case it is simply impossible.

This feature will produce a tangible difference in code generation. For 
example, such parameter cannot be null. For example, Clang will 
aggressively discard branches that would've been taken for a null parameter

https://godbolt.org/z/Y5KKzPbv8

-- 
Best regards,
Andrey Tarasevich

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Usage of static in array declaration Thiago Adams <thiago.adams@gmail.com> - 2021-09-10 07:38 -0700
  Re: Usage of static in array declaration Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-09-10 07:58 -0700
    Re: Usage of static in array declaration Thiago Adams <thiago.adams@gmail.com> - 2021-09-10 09:17 -0700
      Re: Usage of static in array declaration Thiago Adams <thiago.adams@gmail.com> - 2021-09-10 09:37 -0700
      Re: Usage of static in array declaration "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-09-10 09:46 -0700
  Re: Usage of static in array declaration "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-09-10 08:32 -0700
    Re: Usage of static in array declaration Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-09-10 11:26 -0700

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