Re: [PATCH] inttostr.h: add compile-time buffer overrun checks

[Paolo Bonzini]

On 10/25/2010 07:58 PM, Paul Eggert wrote:
> On 10/25/10 03:09, Paolo Bonzini wrote:
>
> > Maybe this could use "func (n, alloca (INT_BUFSIZE_BOUND (t)))" if C99
> > is not in use?
>
> No, alas, because on some hosts, alloca cannot be used within an
> argument to a call.  This is because alloca messes with the stack
> pointer at the same time that the compiler is pushing things onto the
> stack.  This is documented in gnulib's lib/alloca.in.h.

Ugh, makes sense.

> For C89 compilers, possibly we could detect at compile time whether
> it's safe to call alloca from within a function's argument.  (Is this
> safe in GCC?

I can take a look at the code, it is definitely safe with GCC 4 and 
-fno-tree-ter.

Paolo