Re: Moritz Grimm: Wondering about -Wstack-protector

[Hiroaki Etoh <ETOH_(_at_)_jp_(_dot_)_ibm_(_dot_)_com>]

> To: misc_(_at_)_openbsd_(_dot_)_org
> Subject: Wondering about -Wstack-protector
> 
> Hi,
> 
> there is something that I don't understand about Propolice and 
> - -Wstack-protector in gcc or g++.
> 
> When compiling the following program
> 
> $ cat test.c
> int main(void) {return(0);}
> $
> 
> I get:
> 
> $ gcc -Wstack-protector -o test test.c
> test.c: In function `main':
> test.c:1: warning: not protecting variables: it has a variable length 
buffer
> $
> 
> Whenever I use -Wstack-protector I get this warning, and the line it 
> occurs in is always the one with the final `}' of the main() function.
> 
> What does this mean, i.e. how bogus is this warning? I hope it's still 
> doing its Propolice job, but I have to say, this is somewhat confusing.
> 
> 
> Moritz

I understand gcc generates several extra instructions and data when it 
finds "main" function.  There may be a variable length buffer in them.   I 
tried to remove the warning, but I can't distinguish the variable from a 
user-written variable at the RTL level.

Hiroaki Etoh