[erlang-questions] Feedback wanted: Remove compilation times from BEAM files in OTP 19?

[Éric Pailleau]

I agree Loïc,  but native code is in another chunk named with a mnemo of architecture. 
So a same code, compiled native or not will create Beam files with different checksum anyway.
It is a hard problem to solve, with also the constraints to try to keep backward compatibility... Actually I m not sure it is possible to achieve this, or code part have to be in another independent file. This break compatibility... 

"Envoyé depuis mon mobile " Eric

---- Loïc Hoguin a écrit ----

>If you don't have hash(file1) = hash(file2) that means the usual tooling 
>doesn't work as well as it could: packages will do file changes that 
>don't change the program, rsync will do similar with syncs, and so on.
>
>It's also a bit dubious to require Erlang to verify that the Erlang 
>files (including the compiler itself) were compiled as expected.
>
>On 04/08/2016 02:11 PM, Éric Pailleau wrote:
>> Hi,
>> Beam files are separated in different chunks.
>> All dynamic information should be placed in a separate chunck Mho.
>> And sha1sum of code part, or checksum of its canonical abstract code
>> maybe available in a chunk, existing or new one.
>> This could allow to know that a beam, even without the same checksum on
>> the file globally,  run the same code than another Beam file, and so be
>> able to do some Nix like distribution.
>>
>> Compiler version allow to estimate what Erlang version compiled the
>> beam. This is something to keep I think.
>>
>> Regards
>>
>> "Envoyé depuis mon mobile " Eric
>>
>>
>>
>> ---- Matthias Rieber a écrit ----
>>
>> On Fri, 8 Apr 2016, Björn Gustavsson wrote:
>>
>>  > As long as anyone can remember, the compilation time has been included
>>  > in BEAM files (and can be retrieved using module_info()).
>>  >
>>  > As far as I know, the inclusion of the time has only caused problems.
>>  > I can't remember that anyone has found any use for the compilation
>>  > time.
>>  >
>>  > So if we decide to remove the compilation time by default in OTP 19...
>>  >
>>  > ... would it cause any problem for someone in some workflow?
>>
>> I couldn't resist:
>>
>> https://xkcd.com/1172/
>>
>> Matthias
>>
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>
>-- 
>Loïc Hoguin
>http://ninenines.eu
>Author of The Erlanger Playbook,
>A book about software development using Erlang
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