On 3/30/2018 10:38 AM, Diego Biurrun wrote:
> On Fri, Mar 30, 2018 at 12:38:05PM +0200, Steve Lhomme wrote:
>> Le 30/03/2018 à 10:46, Diego Biurrun a écrit :
>>> On Fri, Mar 30, 2018 at 09:36:05AM +0200, Steve Lhomme wrote:
>>>> --- a/configure
>>>> +++ b/configure
>>>> @@ -4581,6 +4582,7 @@ check_lib ole32    "windows.h"            
>>>> CoTaskMemFree        -lole32
>>>>   check_lib shell32  "windows.h shellapi.h" CommandLineToArgvW   -lshell32
>>>>   check_lib wincrypt "windows.h wincrypt.h" CryptGenRandom       -ladvapi32
>>>>   check_lib psapi    "windows.h psapi.h"    GetProcessMemoryInfo -lpsapi
>>>> +check_cpp_condition Vista+ windows.h "_WIN32_WINNT >= 0x0600" && 
>>>> check_lib bcrypt "windows.h bcrypt.h" BCryptGenRandom  -lbcrypt

If you don't need to set any variable then just use test_cpp_condition()

>>> Do you really need to check the Vista condition? What about using bcrypt
>>> unconditionally if available?
>>
>> Yes, you need to use it only on builds that won't run on XP. Otherwise it
>> will fail to load the bcrypt.dll and the whole libavutil DLL (or whatever
>> its form) will fail to load. It would be possible to do it dynamically but
>> IMO it's overkill. It's not really a critical component.
> 
> Is bcrypt available on XP? If no then the CPP condition check would seem
> unnecessary. You could just check for bcrypt and bcrypt being available
> would imply Vista. I think I'm missing something.

check_lib bcrypt "windows.h bcrypt.h" BCryptGenRandom  -lbcrypt

Seems to succeed even if targeting XP, at least on mingw-w64.

> 
>> But with time if XP support is dropped this check can go and wincrypt
>> dropped entirely.
> 
> Is it maybe time to consider dropping XP support?
> 
>>> The variable name with an uppercase letter
>>> and a '+' is slightly odd. I'm not sure if it can cause problems but I
>>> cannot rule it out offhand either.
>>
>> It seems the same is only used in config.log. And the + didn't cause any
>> problem for me.
> 
> I remain sceptical; "it worked for me" is usually not a good argument when
> considering edge cases ;)
> 
> Diego
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