Empty element in CPATH variable

Empty element in CPATH variable

[aiishymanel]

Hi everyone,

the documentation explicitly states that empty elements in CPATH and other variables that control header search path can appear at thebeginning or end of a list. 

https://gcc.gnu.org/onlinedocs/cpp/Environment-Variables.html

But in reality nothing stops you from putting empty element anywhere in the list.

export CPATH="$HOME/include::$HOME/project/include"

cpp -nostdinc /dev/null -o /dev/null -v 2>&1 | awk '/#include/,/End/'

#include "..." search starts here:
#include <...> search starts here:
/root/include
.
/root/project/include
End of search list.

In general I would not consider it to be a bug, but the accent on the beginning and end of the list makes me wonder it it is a bug or a bad description.

Thanks,
Andrii

Re: Empty element in CPATH variable

[Jonathan Wakely]

On Sun, 24 Jul 2022, 13:41 aiishymanel--- via Gcc-help, <
gcc-help@gcc.gnu.org> wrote:

> Hi everyone,
>
> the documentation explicitly states that empty elements in CPATH and other
> variables that control header search path can appear at thebeginning or end
> of a list.
>
> https://gcc.gnu.org/onlinedocs/cpp/Environment-Variables.html
>
> But in reality nothing stops you from putting empty element anywhere in
> the list.
>

I think the idea is that it's obvious that "::" in the middle is an empty
path, but it's saying that it can also appear at the ends, like ":foo".



> export CPATH="$HOME/include::$HOME/project/include"
>
> cpp -nostdinc /dev/null -o /dev/null -v 2>&1 | awk '/#include/,/End/'
>
> #include "..." search starts here:
> #include <...> search starts here:
> /root/include
> .
> /root/project/include
> End of search list.
>
> In general I would not consider it to be a bug, but the accent on the
> beginning and end of the list makes me wonder it it is a bug or a bad
> description.
>

I suppose it could say empty elements can appear anywhere, including the
beginning or end.



> Thanks,
> Andrii
>