fetchurl: Make it overridable using callPackage

[nh2]

Motivation for this change

This provides a workaround for #66499, because this way #66499 (comment)

self: super: {
  fetchurl = super.fetchurl.override (old: {
    curl = old.curl.override {
      gssSupport = false;
      # ...
    };
  });
}

works as expected.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Notify maintainers

cc @infinisil via

[infinisil]

As I was expecting, this doesn't actually change any semantics, so there's no rebuilds, so this can go to master :D. And judging from the evaluation performance report, this isn't that bad for performance either (though it's not negligible):

stat	before	after	Δ	Δ%
cpuTime	159.32	162.18	↗ 2.86	1.79%
envs-bytes	3,104,910,512	3,109,107,072	↗ 4,196,560	0.14%
envs-elements	166,823,790	166,998,908	↗ 175,118	0.10%
envs-number	110,645,012	110,819,738	↗ 174,726	0.16%
gc-heapSize	12,365,262,848	12,382,040,064	↗ 16,777,216	0.14%
gc-totalBytes	24,105,335,232	24,116,554,288	↗ 11,219,056	0.05%
list-bytes	1,608,574,016	1,608,574,976	↗ 960	0.00%
list-concats	7,548,881	7,548,881	0
list-elements	201,071,752	201,071,872	↗ 120	0.00%
nrAvoided	155,782,387	155,783,101	↗ 714	0.00%
nrFunctionCalls	96,490,868	96,665,470	↗ 174,602	0.18%
nrLookups	77,578,468	77,579,037	↗ 569	0.00%
nrOpUpdateValuesCopied	240,027,894	240,028,230	↗ 336	0.00%
nrOpUpdates	13,333,203	13,333,344	↗ 141	0.00%
nrPrimOpCalls	67,845,752	67,846,059	↗ 307	0.00%
nrThunks	159,833,904	159,834,668	↗ 764	0.00%
sets-bytes	8,074,679,456	8,074,714,480	↗ 35,024	0.00%
sets-elements	326,921,442	326,922,789	↗ 1,347	0.00%
sets-number	28,570,606	28,570,943	↗ 337	0.00%
sizes-Attr	24	24	0
sizes-Bindings	8	8	0
sizes-Env	16	16	0
sizes-Value	24	24	0
symbols-bytes	15,063,659	15,063,659	0
symbols-number	331,928	331,928	0
values-bytes	5,615,326,464	5,619,533,208	↗ 4,206,744	0.07%
values-number	233,971,936	234,147,217	↗ 175,281	0.07%

Ping @grahamc because he was interested in this

[nh2]

there's no rebuilds, so this can go to master

Great, I've changed base to master.

[nh2]

@GrahamcOfBorg eval

[nh2]

Does changing base prevent ofborg to eval? I don't see it pop up in the Github checks.

[FRidh]

Please include the motivation in the commit message instead of only referring to a ticket.

[infinisil]

@FRidh I think he did?

[nh2]

Yes, I have in there:

This provides a workaround for #66499, because this way
https://github.com/NixOS/nixpkgs/issues/66499#issuecomment-520277782

    self: super: {
      fetchurl = super.fetchurl.override (old: {
        curl = old.curl.override {
          gssSupport = false;
          # ...
        };
      });
    }

works as expected.

Happy to elaborate more if given some hints what to elaborate on.