Re: git: f7d45c5443ed - main - bhyve: avoid side effect in assertion

> On May 18, 2024, at 8:57 AM, Zhenlei Huang <zlei@FreeBSD.org> wrote:
> 
> 
> 
>> On May 18, 2024, at 4:00 AM, Ed Maste <emaste@freebsd.org> wrote:
>> 
>> The branch main has been updated by emaste:
>> 
>> URL: https://cgit.FreeBSD.org/src/commit/?id=f7d45c5443edc99857fdda19c68301b5ec4a8971
>> 
>> commit f7d45c5443edc99857fdda19c68301b5ec4a8971
>> Author:     Pierre Pronchery <pierre@freebsdfoundation.org>
>> AuthorDate: 2024-05-17 07:31:32 +0000
>> Commit:     Ed Maste <emaste@FreeBSD.org>
>> CommitDate: 2024-05-17 19:45:18 +0000
>> 
>>   bhyve: avoid side effect in assertion
>> 
>>   An assert() was setting the error variable instead of checking it.
>> 
>>   Reported by:    Coverity Scan
>>   CID:            1521431
>>   Reviewed by:    jhb
>>   Sponsored by:   The FreeBSD Foundation
>>   Pull Request:   https://github.com/freebsd/freebsd-src/pull/1244
>> ---
>> usr.sbin/bhyve/tpm_ppi_qemu.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/usr.sbin/bhyve/tpm_ppi_qemu.c b/usr.sbin/bhyve/tpm_ppi_qemu.c
>> index ad66ecb09683..239d39184589 100644
>> --- a/usr.sbin/bhyve/tpm_ppi_qemu.c
>> +++ b/usr.sbin/bhyve/tpm_ppi_qemu.c
>> @@ -161,7 +161,7 @@ tpm_ppi_deinit(void *sc)
>> 	ppi = sc;
>> 
>> 	error = unregister_mem(&ppi_mmio);
>> -	assert(error = 0);
>> +	assert(error == 0);
> 
> Emm, does that not get caught by compilers ?

Unfortunately not. assert is defined as a macro as such

```
#define assert(e)       ((e) ? (void)0 : __assert(__func__, __FILE__, \
                            __LINE__, #e))
```

So `e` is enclosed with () and compiler can not catch that.

> 
>> 
>> 	free(ppi);
>> }
> 
> 
>