On 05/10/2010 01:02 PM, Jim Meyering wrote:
> Eric Blake wrote:
>> For printf("%*s",foo,bar), clang complains if foo is not int:
>>
>> warning: field width should have type 'int', but argument has
>> type 'unsigned int' [-Wformat]
>>
>> virStorageEncryptionSecretFormat(virBufferPtr buf,
>> virStorageEncryptionSecretPtr secret,
>> - unsigned int indent)
>> + int indent)
>
> "unsigned int" sounds like the right type to me, since
> "indent" never goes negative. And using the unsigned type
> seems to be in line with policy in HACKING:
>
> If a variable is counting something, be sure to declare it with an
> unsigned type.
But printf("%*s", indent, string) would indeed behave differently if
indent goes negative (if signed) or larger than INT_MAX (if unsigned),
so clang's warning is realistic, and worth silencing in our quest to get
a clean clang build. About the only other thing I could think of to do
that would avoid confusion and also to avoid casts is to keep the public
interface with unsigned int, then add an intermediate helper variable:
int real_indent = indent;
and use real_indent in the printf call, but that seems like overkill.
>
> Of course, avoiding casts is good, too, but IMHO, not if
> it makes us obfuscate (even ever so slightly) the types we use.
Well, the real point of this patch was to silence a compiler warning
(not that we'd ever planning on passing an indent > 2G). Given Dave's
ACK, I went ahead and applied v2 as proposed, even if it does slightly
obfuscate the usage.
--
Eric Blake eblake@xxxxxxxxxx +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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