On 01/07/11 11:23, Dejan Muhamedagic wrote:
> Hi,
>
> On Fri, Jul 01, 2011 at 01:37:32AM +0100, Pádraig Brady wrote:
>> On 30/06/11 20:33, Lars Ellenberg wrote:
>>> On Wed, Jun 29, 2011 at 12:55:08PM +0100, Pádraig Brady wrote:
>>>> On 29/06/11 11:56, Lars Ellenberg wrote:
>>>>> On Tue, Jun 28, 2011 at 01:44:23AM +0100, Pádraig Brady wrote:
>>>>>> The attached patch fixes compilation -Werrors with GCC 4.6
>>>>>>
>>>>>> cheers,
>>>>>> Pádraig.
>>>>>>
>>>>>
>>>>>> Fix compilation with GCC 4.6
>>>>>>
>>>>>> avoid -Werror=unused-but-set-variable issues
>>>>>> remove -Wcast-qual which caused issues with copyHostList()
>>>>>
>>>>> Care to explain or show those "issues"?
>>>>
>>>> All uses of copyHostList error like:
>>>>
>>>> apcsmart.c: In function 'apcsmart_hostlist':
>>>> apcsmart.c:722:34: error: to be safe all intermediate pointers in cast
>>>> from 'char **' to 'const char **' must be 'const' qualified
>>>> [-Werror=cast-qual]
>>>
>>> From the gcc 4.5 documentation:
>>> -Wcast-qual
>>> Warn whenever a pointer is cast so as to remove a type qualifier from
>>> the target
>>> type. For example, warn if a const char * is cast to an ordinary char *.
>>> Also warn when making a cast which introduces a type qualifier in an
>>> unsafe
>>> way. For example, casting char ** to const char ** is unsafe, as in
>>> this ex-
>>> ample:
>>> /* p is char ** value. */
>>> const char **q = (const char **) p;
>>> /* Assignment of readonly string to const char * is OK.
>>> *q = "string";
>>> /* Now char** pointer points to read-only memory. */
>>> **p = ’b’;
>>>
>>> So apparently it needs to be
>>>
>>> include/stonith/stonith_plugin.h:
>>> struct StonithImports_s {
>>> ...
>>> - char **(*CopyHostList)(const char ** hlstring);
>>> + char **(*CopyHostList)(const char * const * hlstring);
>>>
>>> And the callers have to be adjusted accordingly?
>>> Could you check if that works?
>>
>> Sure, that would work but would involve a lot of changes I think.
>> I was unsure how changing this interface might affect users
>> outside this project, but if that's OK I'll go ahead
>> and change that (tomorrow when I'm more awake).
>
> It should be OK. It is a change which may break compilation, then
> if somebody's using the libraries they should fix their code
> accordingly.
I had another look, and I think this introduces too much churn.
Sometimes new GCC warnings are a little intrusive for general use
and I think -Wcast-qual is in this category for the moment.
The specific pattern at issue here is:
char ** array_of_strings;
One should be able to cast to the appropriate
level of constness to:
sort (const char**);
copy (const char* const*);
free (char **);
So please consider my last patch instead.
cheers,
Pádraig.
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