Bug#894476: RCC: provide option to encode EPOCH timestamp

[Sune Vuorela <sune@debian.org>]

On Saturday, March 31, 2018 12:05:02 PM CEST Chris Lamb wrote:
> > While investigating ultracopier's lack of build reproducibility, I found
> > out that rcc encodes the timestamp of the files the QRC file being
> > compiled references

I don't actually see why this should be a problem. If input changes, output 
changes.
I do think that using touch(1) on the input should allow different output.

It is quite easy to reproduce:

qtbase/tests/auto/gui/image/qimage/foo (dev $%=)$ rcc --format-version 2 ../
qimage.qrc -o 1
qtbase/tests/auto/gui/image/qimage/foo (dev $%=)$ rcc --format-version 2 ../
qimage.qrc -o 2
qtbase/tests/auto/gui/image/qimage/foo (dev $%=)$ rcc --format-version 2 ../
qimage.qrc -o 3

Gives same output.
Even adding in touch ../qimage.qrc keeps the same output.

qtbase/tests/auto/gui/image/qimage/foo (dev $%=)$ rcc --format-version 2 ../
qimage.qrc -o 4

touch ../images/image.bmp

qtbase/tests/auto/gui/image/qimage/foo (dev $%=)$ rcc --format-version 2 ../
qimage.qrc -o 5

is needed to get different output

14ef6dae8e4992ce907948c1c4af272b  1
14ef6dae8e4992ce907948c1c4af272b  2
14ef6dae8e4992ce907948c1c4af272b  3
14ef6dae8e4992ce907948c1c4af272b  4
54c6f8c09a347955ae2f36e68bbd2539  5


So. What touches the files?

/Sune
-- 
I didn’t stop pretending when I became an adult, it’s just that when I was a 
kid I was pretending that I fit into the rules and structures of this world. 
And now that I’m an adult, I pretend that those rules and structures exist.
   - zefrank