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Subject: Re: [Qemu-devel] [PATCH 02/22] eepro100: cast a void * makes no sense
References: <cover.1251111439.git.quintela@redhat.com>
	<51486eb6860d1680c1bce45e310dcd3aae096f43.1251111439.git.quintela@redhat.com>
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From: Markus Armbruster <armbru@redhat.com>
Date: Mon, 24 Aug 2009 15:51:20 +0200
In-Reply-To: <4A928DF0.9000106@weilnetz.de> (Stefan Weil's message of "Mon\,
	24 Aug 2009 14\:56\:16 +0200")
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To: Stefan Weil <Stefan.Weil@weilnetz.de>
Cc: qemu-devel@nongnu.org, Juan Quintela <quintela@redhat.com>

Stefan Weil <Stefan.Weil@weilnetz.de> writes:

> Juan Quintela schrieb:
>> Signed-off-by: Juan Quintela <quintela@redhat.com>
>> ---
>>  hw/eepro100.c |    6 +++---
>>  1 files changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/hw/eepro100.c b/hw/eepro100.c
>> index 0031d36..09083c2 100644
>> --- a/hw/eepro100.c
>> +++ b/hw/eepro100.c
>> @@ -507,7 +507,7 @@ static void nic_selective_reset(EEPRO100State * s)
>>
>>  static void nic_reset(void *opaque)
>>  {
>> -    EEPRO100State *s = (EEPRO100State *) opaque;
>> +    EEPRO100State *s = opaque;
>>      logout("%p\n", s);
>>      static int first;
>>      if (!first) {
>> @@ -1544,7 +1544,7 @@ static ssize_t nic_receive(VLANClientState *vc, const uint8_t * buf, size_t size
>>
>>  static int nic_load(QEMUFile * f, void *opaque, int version_id)
>>  {
>> -    EEPRO100State *s = (EEPRO100State *) opaque;
>> +    EEPRO100State *s = opaque;
>>      int i;
>>      int ret;
>>
>> @@ -1634,7 +1634,7 @@ static int nic_load(QEMUFile * f, void *opaque, int version_id)
>>
>>  static void nic_save(QEMUFile * f, void *opaque)
>>  {
>> -    EEPRO100State *s = (EEPRO100State *) opaque;
>> +    EEPRO100State *s = opaque;
>>      int i;
>>
>>      if (s->pci_dev)
>>   
>
> I wrote these type casts, and I think they make sense.
> In C++ code, they are even mandatory.

Yes, but this isn't C++.

> I think the arguments why C++ requires this kind of
> type casts apply to C code (like in Qemu) as well.
>
> If it is possible with no or very litte efforts to write
> code which is C and C++ compatible, I prefer to do so.

I respectfully disagree.  Casts from "void *" to "T *" are pure noise.
Getting into the habit of writing noise casts runs the risk of silencing
warnings that flag real type errors.