Change default date of nix store to increase compatibility?

[tbenst]

Issue description

I often see problems like https://nixos.org/nixpkgs/manual/#python-setup.py-bdist_wheel-cannot-create-.whl due to the default timestamp on NixOS. It seems that dates after 1980 are widely supported across UNIX and DOS, whereas prior to 1980 is often not supported by DOS programs that are later ported to UNIX.

Given that Jan 1, 1970 is completely arbitrary and made up, can we change to the DOS date for nix store to increase compatibility? eg SOURCE_DATE_EPOCH=315532800 instead of 1.

[vcunat]

We use this hook by default: https://github.com/NixOS/nixpkgs/blob/master/pkgs/build-support/setup-hooks/set-source-date-epoch-to-latest.sh

[vcunat]

It's just switching from one arbitrary date to another. When doing this, I'd anticipate that some "new modern framework" will come that will assume that anything before 2010 can be ignored. The shift might help in practice, though... but I suspect nixpkgs/stdenv won't be enough and we'd need to shift nix store dates as well, i.e. break its compatibility.

[tbenst]

Yes, thanks @volth. @vcunat you are right that developers are free to hardcode other date assumptions and my lay perception is also that we would have to shift nix store dates to fix

[FRidh]

I don't see this happening so closing.

[twhitehead]

Just a note that you can't build epub documents using sphinx due to this. Further, it seems to be choking on pulling a mimetypes file from the store (as predicted would happen)... 😁

$ make epub
...
Traceback (most recent call last):
  File "/nix/store/aar6diwl9bw72bckp21zpiclmcpyg9hr-python3.8-sphinx-3.0.3/lib/python3.8/site-packages/sphinx/cmd/build.py", line 280, in build_main
    app.build(args.force_all, filenames)
  File "/nix/store/aar6diwl9bw72bckp21zpiclmcpyg9hr-python3.8-sphinx-3.0.3/lib/python3.8/site-packages/sphinx/application.py", line 348, in build
    self.builder.build_update()
  File "/nix/store/aar6diwl9bw72bckp21zpiclmcpyg9hr-python3.8-sphinx-3.0.3/lib/python3.8/site-packages/sphinx/builders/__init__.py", line 297, in build_update
    self.build(to_build,
  File "/nix/store/aar6diwl9bw72bckp21zpiclmcpyg9hr-python3.8-sphinx-3.0.3/lib/python3.8/site-packages/sphinx/builders/__init__.py", line 364, in build
    self.finish()
  File "/nix/store/aar6diwl9bw72bckp21zpiclmcpyg9hr-python3.8-sphinx-3.0.3/lib/python3.8/site-packages/sphinx/builders/html/__init__.py", line 623, in finish
    self.handle_finish()
  File "/nix/store/aar6diwl9bw72bckp21zpiclmcpyg9hr-python3.8-sphinx-3.0.3/lib/python3.8/site-packages/sphinx/builders/epub3.py", line 82, in handle_finish
    self.build_epub()
  File "/nix/store/aar6diwl9bw72bckp21zpiclmcpyg9hr-python3.8-sphinx-3.0.3/lib/python3.8/site-packages/sphinx/builders/_epub_base.py", line 730, in build_epub
    epub.write(path.join(outdir, 'mimetype'), 'mimetype', ZIP_STORED)
  File "/nix/store/z65l1jqvxa58zzwwa3bvglb6asj4y8cv-python3-3.8.5/lib/python3.8/zipfile.py", line 1741, in write
    zinfo = ZipInfo.from_file(filename, arcname,
  File "/nix/store/z65l1jqvxa58zzwwa3bvglb6asj4y8cv-python3-3.8.5/lib/python3.8/zipfile.py", line 539, in from_file
    zinfo = cls(arcname, date_time)
  File "/nix/store/z65l1jqvxa58zzwwa3bvglb6asj4y8cv-python3-3.8.5/lib/python3.8/zipfile.py", line 362, in __init__
    raise ValueError('ZIP does not support timestamps before 1980')

Was looking through the zipfile.py source code though, and happened to notice this

        if not strict_timestamps and date_time[0] < 1980:
            date_time = (1980, 1, 1, 0, 0, 0)
        elif not strict_timestamps and date_time[0] > 2107:
            date_time = (2107, 12, 31, 23, 59, 59)

Looks like the default is strict_timestamps=True

    def from_file(cls, filename, arcname=None, *, strict_timestamps=True):

Could be a reasonable thing to patch I think.

[FRidh]

stdenv was changed in #89794