Re: [PATCH] ib-diags: Add cast to fix build on windows

[Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>]

On Thu, Sep 22, 2011 at 08:20:54PM +0000, Hefty, Sean wrote:
 
> The entire windows tree is built using the WinDDK compiler.  I
> haven't found a way to disable that warning that works.  Since the
> warning is real, an explicit cast at least lets someone reading the
> code know that the author took truncation into account.

It would be much better to fix this at the source.

 mad_get_field16(..,IB_NODE_DEVID_F)

Then at least there is the option of doing a static or runtime check
that IB_NODE_DEVID_F is actually referring to a 16 bit field.

For instance, a static check might be possible with some compilers by
doing:

enum MAD_FIELDS8
{
IB_PORT_LOCAL_PORT_F
};

enum MAD_FIELDS16
{
IB_NODE_DEVID_F
};

uint8_t mad_get_field8(void *buf, int base_offs,
	               enum MAD_FIELDS8 field);
uint16_t mad_get_field16(void *buf, int base_offs,
	                 enum MAD_FIELDS16 field);

A compiler can produce a warning about mismatching enums.

Someone can fixup the enums later, but I'd much rather see you add a
patch with this hunk:

static inline uint16_t mad_get_field16(void *buf, int base_offs,
	                               enum MAD_FIELDS field)
{
   return (uint16_t)mad_get_field(buf,base_offs,field);
}

And another patch replacing every (uint16_t)mad_get_field with
mad_get_field16

Adding a cast is just pointless noise, doesn't fix or prove anything.

Jason
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