Re: [dpdk-dev] [PATCH] mk: toolchain: gcc: query the compiler macros to obtain the gcc version

[Markos Chandras <mchandras@suse.de>]

Hi,

On 22/03/16 22:34, Thomas Monjalon wrote:
> 2016-03-22 17:13, Markos Chandras:
>> This is similar to what's being used in the Linux kernel. Querying the
>> GCC macros directly gives more accurate results compared to -dumpversion
>> which could vary across distributions.
>>
>> Signed-off-by: Markos Chandras <mchandras@suse.de>
>> ---
>> In openSUSE Tumbleweed (and in any other SUSE distribution which
>> uses (or will use) gcc >= 5), gcc -dumpversion returns '5'. This is on
>> purpose as discussed in https://bugzilla.opensuse.org/show_bug.cgi?id=941428
> 
> Good to know. It could be in the commit log.

I can add this information to the commit message and send a v2 if needed.

> 
>> -GCC_VERSION = $(subst .,,$(shell $(CC) -dumpversion | cut -f1-2 -d.))
>> +GCC_MAJOR = $(shell echo __GNUC__ | $(CC) -E -x c - | tail -n 1)
>> +GCC_MINOR = $(shell echo __GNUC_MINOR__ | $(CC) -E -x c - | tail -n 1)
>> +GCC_VERSION = $(GCC_MAJOR)$(GCC_MINOR)
> 
> Are we sure the minor will always be only one digit?
> 

Well, I can't be sure but minor has always been a single digit since gcc
>= 3 if I am not mistaken. But does it matter? What if it is two or more
digits? The previous code did something similar so if you had gcc
5.12.34 installed (and lets assume this is what is being returned by
-dumpversion), it would have returned 512. The comparison would still
work as it is at the moment no?

-- 
markos