This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH] treat -Wxxx-larger-than=HWI_MAX special (PR 86631)


On 07/26/2018 02:38 AM, Richard Biener wrote:
On Wed, Jul 25, 2018 at 5:54 PM Martin Sebor <msebor@gmail.com> wrote:

On 07/25/2018 08:57 AM, Jakub Jelinek wrote:
On Wed, Jul 25, 2018 at 08:54:13AM -0600, Martin Sebor wrote:
I don't mean for the special value to be used except internally
for the defaults.  Otherwise, users wanting to override the default
will choose a value other than it.  I'm happy to document it in
the .opt file for internal users though.

-1 has the documented effect of disabling the warnings altogether
(-1 is SIZE_MAX) so while I agree that -1 looks better it doesn't
work.  (It would need more significant changes.)

The variable is signed, so -1 is not SIZE_MAX.  Even if -1 disables it, you
could use e.g. -2 or other negative value for the other special case.

The -Wxxx-larger-than=N distinguish three ranges of argument
values (treated as unsigned):

   1.  [0, HOST_WIDE_INT_MAX)
   2.  HOST_WIDE_INT_MAX
   3.  [HOST_WIDE_INT_MAX + 1, Infinity)

But it doesn't make sense for those to be host dependent.

It isn't when the values are handled by each warning.  That's
also the point of this patch: to remove this (unintended)
dependency.

I think numerical user input should be limited to [0, ptrdiff_max]
and cases (1) and (2) should be simply merged, I see no value
in distinguishing them.  -Wxxx-larger-than should be aliased
to [0, ptrdiff_max], case (3) is achieved by -Wno-xxx-larger-than.

I think you are over-engineering this and the user-interface is
awful.

Thank you.

I agree that what you describe would be the ideal solution.
As I explained in the description of the patch, I did consider
handling PTRDIFF_MAX but the target-dependent value is not
available at the time the option argument is processed.  We
don't even know yet what the target data model is.

This is the best I came up with.  What do you suggest instead?

Martin


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]