[erlang-bugs] (unconditional) rebuild caused by gen_git_version

[Lukas Larsson]

Hello,

When implementing this I noticed it as well and tried to do something 
about it. Alas it proved quite difficult and I had to settle on a 
compromise where it does a rebuild once. i.e.

commit change
make
LD
make
LD
make
make
make
make

At least that is the way it works for me on Ubuntu Linux.

If someone else feels like having a go at making it work they are most 
welcome.

Lukas

On 18/02/14 18:53, Tuncer Ayaz wrote:
> On Tue, Feb 18, 2014 at 1:40 PM, Tuncer Ayaz wrote:
>> Since R16 it's not possible anymore to quickly run make in a
>> previously built and otherwise unmodified tree.
>>
>> $ make
>> # everything built
>> # run make again
>> $ make
>> ...
>>   GEN    x86_64-unknown-linux-gnu/gen_git_version.mk
>>   CC     obj/x86_64-unknown-linux-gnu/opt/plain/erl_bif_info.o
>> ..
>>   LD     /tmp/otp/master/bin/x86_64-unknown-linux-gnu/beam
>>
>> This doesn't take long, but recreating an object file and relinking
>> the vm every time doesn't seem right to me. AFAICT, it was introduced
>> to include the git revision of the tree the vm was built from.
>>
>> I don't have time to look into this right now, so no patch from me.
> If anyone wants to submit a fix, presumably adding a check that
> compares the previous build's git revision for inequality should fix
> the bug. I assume it's probably already cached in a file.
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