On 08/22, David Laight wrote:

...

quoted

quoted

That typecheck() is horrid.
It may well have caused more bugs due to incorrect casts that
it actually detected.

I'd suggest the version that just avoids multiple evaluations.
Or just error signed v unsigned comparisons.
See  https://lore.kernel.org/all/b4ce9dad748e489f9314a2dc95615033@AcuMS.aculab.com/ (local)
for an example patch set.

Interesting, thanks. That is also simpler.

Also, the existing patch is no worse than the open coded code today,
so even without code to avoid multiple evaluations, I guess it's okay
to merge.

The coccinelle warnings are arguably false positives, using checks for
kernel code, but being run against userspace code that has no access
to those helpers. But fine to silence them.

You can't use is_constexpr() unless 'sizeof *(void *)' is valid.
And builtin_constant() isn't good enough for builtin_choose_expr().

That might be ok for selftests and tools, but not for generaluserspace.

	David

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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

I tried to use the relaxed version provided in the shared patchset link 
besides not able to use is_constexpr(), I'm not able to use
__UNIQUE_ID() also. It's definded inside include/linux/compiler-gcc.h
and it uses another macro __PASTE() which is defined inside
include/linux/compiler_types.h. 
not sure what to do next
- bring those macros definitions to able to use the relaxed version.
- if the most important point for min/max defines inside selftests is to
  avoid multiple evaluation is the below version acceptable?
  /*
  #define min(x, y) ({ \
    typeof(x) _x = (x); \
    typeof(y) _y = (y); \
    _x < _y ? _x : _y; \
})

#define max(x, y) ({ \
    typeof(x) _x = (x); \
    typeof(y) _y = (y); \
    _x > _y ? _x : _y; \
})
*/
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