curl overrides are discarded when pulled in via fetchpatch, but overrideAttrs are not

[nh2]

I have this blocker problem currently for musl builds in static-haskell-nix:

When I override curl in an overlay, while also adding a fetchpatch to the proper libdrm/default.nix, then the the fetchpatch causes curl to build and fail with linker error.

That is because while it does build the curl from my overlay, it seems to ignore what I've given in .override (e.g. I give gssSupport = false, but inside e.g. configurePhase it's still true again).

I basically do in my overlay

{
  curl = (previous.curl.override { gssSupport = false; }).overrideAttrs (old: {
    makeFlags = ["V=1"];
  });
}

and observe that the V=1 is in effect, but the gssSupport = false is not.

(I see that in nix show-derivation on the .drv.)

What's going on here?

---

cc from IRC: @matthewbauer @Ericson2314 @dtzWill @cleverca22

Environment

commit bc94dcf

[nh2]

To repro this:

git clone --recursive https://github.com/nh2/static-haskell-nix.git -b nixpkgs-66499-problem-repro-curl-override-discarded
cd static-haskell-nix
NIX_PATH=. nix-build --no-link survey/default.nix --arg disableOptimization true -A pkgs.libdrm

(this is the branch in nh2/static-haskell-nix#45)

---

It prints

...
trace: gssSupport true
these derivations will be built:
  /nix/store/bkk1f6ls0rm6xz4l2fyy9gxlzlfafy7x-curl-7.64.1.drv
  /nix/store/2hcg7wnzyqamdy68y1rhcpqf0gap1jl9-musl-ioctl.patch.drv
  /nix/store/150vlxnw31ida8wr45fknywjm8kkn7hs-libdrm-2.4.97.drv
building '/nix/store/bkk1f6ls0rm6xz4l2fyy9gxlzlfafy7x-curl-7.64.1.drv'...
...
configuring

gssSupport true

exiting
builder for '/nix/store/bkk1f6ls0rm6xz4l2fyy9gxlzlfafy7x-curl-7.64.1.drv' failed with exit code 1

And

% nix show-derivation /nix/store/bkk1f6ls0rm6xz4l2fyy9gxlzlfafy7x-curl-7.64.1.drv | grep -E 'configureFlags|makeFlags'
      "configureFlags": "--without-ca-bundle --without-ca-path --with-ca-fallback --disable-manual --with-ssl=/nix/store/c7ax9w05g2vp36wm0j695fbh89dma2rq-openssl-1.0.2r-dev --without-gnutls --with-libssh2=/nix/store/a6crgyyg9v9splnidqmz2530q888cf6l-libssh2-1.8.2-dev --disable-ldap --disable-ldaps --without-libidn --without-brotli --with-gssapi=/nix/store/q82pls5sglxi3bi49r7m736kz01pqmkc-libkrb5-1.17-dev",
      "makeFlags": "curl_LDFLAGS=-all-static V=1",

shows that my makeFlags from here made it in but --with-gssapi is given even though I give gssSupport = false here.

[nh2]

Is there some magic somewhere that makes that fetchpatch -> fetchurl -> curl discards curl.override in overlays but retains curl.overrideAttrs?

[nh2]

Some info from @infinisil:

Not sure, but curl is a bit special in that a modified version is used for pkgs.fetchurl

nixpkgs/pkgs/top-level/all-packages.nix

Line 278 in ac2eb31

curl = buildPackages.curl.override rec {

There buildPackages.curl is used with gssSupport overwritten

I confirmed:

that place certainly seems to be very involved in the problem, if I set gssSupport = false; then it's false in my build

So indeed that place just overrides my .override but not my overrideAttrs.

How can I make my .override take precedence?

[infinisil]

Maybe something like

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

[nh2]

I should also mention why I actually want to do that:

In my overlay, I want to have libcurl and libkrb5 have static libraries (.a files).

So I do

{
    krb5 = previous.krb5.override {
      # Note krb5 does not support building both static and shared at the same time.
      # That means *anything* on top of this overlay trying to link krb5
      # dynamically from this overlay will fail with linker errors.
      staticOnly = true;
    };

    # Disable gss support, because that requires `krb5`,
    # which (as mentioned above) is a library that cannot build both
    # .a and .so files in its build system.
    # That means that if we enable it, we can no longer build the
    # dynamically-linked `curl` binary from this overlay.
    # But `fetchurl`, `fetchpatch` and so on by default depend on dynamically
    # linked `curl` binaries.
    curl = (previous.curl.override { gssSupport = false; }).overrideAttrs (old: {
      dontDisableStatic = true;
    });
}

See the dilemma? Having krb5 .a files means there will be no .so files for it, which means curl can't find krb5 .so files, so I must disable that feature for curl.

[nh2]

fetchurl = super.fetchurl.override (old: {

That doesn't work, because super.fetchurl is a function taking { url, ... }, not a derivation, so it doesn't have an .override attribute.

It seems fetchurl can't be overridden.

[nh2]

@infinisil said:

Try changing nixpkgs fetchurl = import ../build-support/fetchurl to `fetchurl = callPackage ...

Indeed callPackage seems to make it work.

me:

Should that be changed this way?

@infinisil siad:

Yeah I'd say so
Seeing the eval stats for that will be interesting

[nh2]

I found the fix in #66506.