fix C++ compile errors (FreeBSD-current) #1245
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sys/netlink/netlink_snl.h
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| @@ -63,7 +63,7 @@ | |||
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| #define _NLA_END(_start, _len) ((char *)(_start) + (_len)) | |||
| #define NLA_FOREACH(_attr, _start, _len) \ | |||
| for (_attr = (_start); \ | |||
| for (_attr = (typeof(_attr))(_start); \ | |||
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typeof is a compiler extension, it was added in C23.
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So no then. We don't enable c23 for the kernel at all.
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changed to use __typeof instead
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Uh how about doing...
#ifdef __cplusplus
# define NLA_FOREACH(_attr, _start, _len) \
for (_attr = (decltype(_start))(_start); \
((char *)_attr < _NLA_END(_start, _len)) && \
((char *)NLA_NEXT(_attr) <= _NLA_END(_start, _len)); \
_attr = NLA_NEXT(_attr))
#else
# define NLA_FOREACH(_attr, _start, _len) \
for (_attr = (_start); \
((char *)_attr < _NLA_END(_start, _len)) && \
((char *)NLA_NEXT(_attr) <= _NLA_END(_start, _len)); \
_attr = NLA_NEXT(_attr))
#endifThis one would be valid C and C++ code (without using any compiler extensions)... but the only issue (visually) is that two similar macros, one for C and one for C++
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Splitting it into two macros might make future maintenance inconvenience.
How about I change it to (struct nlattr *) just like NLA_NEXT at line 62?
NLA_FOREACH macro uses NLA_NEXT internally, and NLA_NEXT is directly cast as (struct nlattr *).
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So no then. We don't enable c23 for the kernel at all.
typeof() should be fine in practice. Compiling the following fragment on compiler explorer says clang >= 11 and gcc >= 10 support it with default flags.
int a;
typeof(a) b;
sys/netlink/netlink_snl.h
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| @@ -102,7 +102,7 @@ lb_allocz(struct linear_buffer *lb, int len) | |||
| len = roundup2(len, alignof(__max_align_t)); | |||
| if (lb->offset + len > lb->size) | |||
| return (NULL); | |||
| void *data = (void *)(lb->base + lb->offset); | |||
| char *data = (lb->base + lb->offset); | |||
| lb->offset += len; | |||
| return ((char *)data); | |||
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Since you've used char *data ... you can safely remove this cast
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This looks to be the only active comment, and the only thing that has caught my eye that's in the way of committing.
Allow these files to be included in C++ programs with careful casting to the proper type, like C++ wants (and in a way that also works for C). MFC After: 1 week Reviewed by: imp Pull Request: freebsd#1245
Trying to fix the errors of Bug 279054 - Compile failure when #include <netlink/netlink_snl.h> in C++ code (edit)