On Fri, Mar 16, 2018 at 9:14 PM, Linus Torvalds
[off-list ref] wrote:

On Fri, Mar 16, 2018 at 1:03 PM, Miguel Ojeda
[off-list ref] wrote:

quoted

quoted

Kees - is there some online "gcc-4.4 checker" somewhere? This does
seem to work with my gcc. I actually tested some of those files you
pointed at now.

I use this one:

  https://godbolt.org/

Well, my *test* code works on that one and -Wvla -Werror.

It does not work with gcc-4.1.x, but works with gcc-4.4.x.

I can't seem to see the errors any way, I wonder if
__builtin_choose_expr() simply didn't exist back then.

Odd that you can't view warnings/errors with it.

But it's possible that it fails on more complex stuff in the kernel.

I've done a "allmodconfig" build with that patch, and the only issue
it found was that (real) type issue in tpm_tis_core.h.

Just tested your max() with a Python script I wrote yesterday to try a
lot of combinations for this thing. Your version gives some warnings
in some cases, like:

  warning: signed and unsigned type in conditional expression [-Wsign-compare]
   #define __cmp(a,b,op) ((a)op(b)?(a):(b))

  warning: comparison between signed and unsigned integer expressions
[-Wsign-compare]
   #define const_max(a,b)              __careful_cmp(a,b,>)

  warning: comparison of distinct pointer types lacks a cast
           (!!(sizeof((typeof(a)*)1==(typeof(b)*)1)))

But it fails on something like (with warnings):

  int a[const_max(-30, 60u)];

Sorry... :-(

Has anyone taken a look at the last one I sent? Patch attached with
the draft changes on the kernel. It compiles fine the cases Kees
cleaned up in the other patch, but also works without a explicit type,
for mixed types, and for both positive and negative values.

Cheers,
Miguel