Re: Spurious warning for zero-sized array parameters to a function

[Alejandro Colomar via Gcc]

Hi Richard,

On 12/7/22 09:17, Richard Biener wrote:
[...]

The warnings are invalid.  While it's true that I'm referencing a pointer of
size 0, it's false that I'm "accessing 1 byte" in that region.  I guess this is
all about the bogus design of 'static' in ISO C, where you can have an array
parameter of size 0, which is very useful in cases like this one.

It looks like we run into pass_waccess::maybe_check_access_sizes doing

       if (sizidx == -1)
         {
           /* If only the pointer attribute operand was specified and
              not size, set SIZE to the greater of MINSIZE or size of
              one element of the pointed to type to detect smaller
              objects (null pointers are diagnosed in this case only
              if the pointer is also declared with attribute nonnull.  */
           if (access.second.minsize
               && access.second.minsize != HOST_WIDE_INT_M1U)
             access_nelts = build_int_cstu (sizetype, access.second.minsize);
           else if (VOID_TYPE_P (argtype) && access.second.mode == access_none)
             /* Treat access mode none on a void* argument as expecting
                as little as zero bytes.  */
             access_nelts = size_zero_node;
           else
             access_nelts = size_one_node;

and use size_one_node as fallback - it either doesn't consider [0] "valid" or
for some reason chooses to interpret it as "unknown".  Can you file a bugreport
please?

Sure;  will do!

Cheers,

Alex

Martin?

Richard.

--
<http://www.alejandro-colomar.es/>

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