[OE-core] TARGET_CFLAGS for non-target builds

[Andre McCurdy]

On Mon, Feb 8, 2016 at 4:01 PM, Mark Hatle <mark.hatle at windriver.com> wrote:
> On 2/8/16 5:43 PM, Andre McCurdy wrote:
>> On Mon, Feb 8, 2016 at 3:00 PM, Burton, Ross <ross.burton at intel.com> wrote:
>>>
>>> On 8 February 2016 at 20:03, Andre McCurdy <armccurdy at gmail.com> wrote:
>>>>
>>>> Can you give an example? Looking at native.bbclass it seems to replace
>>>> TARGET_CFLAGS with BUILD_CFLAGS, not manipulate it.
>>>
>>> Sure, so in doing a native build TARGET_CFLAGS is used.  But as
>>> security_flags.inc was using TARGET_CFLAGS_append, the end result was
>>> BUILD_CFLAGS appended with the security flags.
>>
>> Yes, for native, TARGET_CFLAGS will end up being "${BUILD_CFLAGS}
>> ${SECURITY_CFLAGS}".
>>
>> However it shouldn't matter - native.bbclass sets CFLAGS to
>> BUILD_CFLAGS, not TARGET_CFLAGS.
>>
>> Do you have an example where host gcc can legitimately be invoked with
>> TARGET_CFLAGS?
>
> You have to remember the order of the operators.  _append says to make the
> append, AFTER everything else has been evaluated (and before _remove).  This
> includes override behaviors.
>
> So if you do:
>
> TARGET_CFLAGS = "-deadbeef"
> BUILD_CFLAGS = "-badc0ffee"
> TARGET_CFLAGS_append = " -foobar"
> TARGET_CFLAGS = "${BUILD_CFLAGS}"
>
> The final value of TARGET_CFLAGS is "-badc0ffee -foobar"
>
> Thus by changing the append to:
>
> TARGET_CFLAGS_append_class-target = " -foobar"
> TARGET_CFLAGS_class-native = "${BUILD_CFLAGS}"
>
> In the case where the 'class-target' is the override you will get:
>
> TARGET_CFLAGS = "-deadbeef -foobar"
>
> In the case where the 'class-native' is the override you will get:
>
> TARGET_CFLAGS = "-badc0ffee"

I'm not disputing that TARGET_CFLAGS can contain something bogus for a
class-native build.

I'm asking why does it matter?

Setting TARGET_CFLAGS at all in native.bbclass is fairly recent and
seems to be a workaround to avoid churning sstate:

  http://git.openembedded.org/openembedded-core/commit/?id=05a70ac30b37cab0952f1b9df501993a9dec70da

Is that perhaps still the real reason to avoid modifying TARGET_CFLAGS
for a native build?


> --Mark