Qtbase with NIX_CFLAGS_COMPILE overlay in stdenv

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1

Similar to my previous thread, I have the following overlay to my configuration, which qtbase fails to build with.

(
  self: super: {
    .
    .
    .
    stdenv = super.stdenv // {
      mkDerivation = args: super.stdenv.mkDerivation (
        args // {
          NIX_CFLAGS_COMPILE = toString (args.NIX_CFLAGS_COMPILE or "") + " -pipe - march=skylake -O3";
        }
      );
    };
    .
    .
    .
  }
)

qtbase’s derivation has this in its env:

"NIX_CFLAGS_COMPILE": "-Wno-error=sign-compare -DNIXPKGS_QTCOMPOSE=\"/nix/store/myn5q5p002n997p2g19x4mf01cjwp1w2-libX11-1.6.12/share/X11/locale\" -DLIBRESOLV_SO=\"/nix/store/iz8q8dbqxkhsmjn9mf86wmrxj8bfpiyd-glibc-2.31/lib/libresolv\" -DNIXPKGS_LIBXCURSOR=\"/nix/store/d4440walblw18jayilyg6iy9zi7xjx2y-libXcursor-1.2.0/lib/libXcursor\" -DNIXPKGS_MESA_GL=\"/nix/store/awldp19kp9d8i1kbnc87h5md0n4h40h2-libGL-1.3.2/lib/libGL\" -DNIXPKGS_QGTK3_XDG_DATA_DIRS=\"/nix/store/b9n6f0hpmgg3ajwq19mdgp60fs9fqlpv-gtk+3-3.24.21/share/gsettings-schemas/gtk+3-3.24.21\" -DNIXPKGS_QGTK3_GIO_EXTRA_MODULES=\"/nix/store/a6xb7whs613zf2d4rsda9r4c9jddgy4p-dconf-0.36.0-lib/lib/gio/modules\" -pipe -march=skylake -O3"

Qtbase is provided by qt5.qtbase defined here. After spending days trying different things, I have been unable to stop -O3 from getting added to qtbase.

2

Would an overlay like this work?

(
  self: super: {
    qt5.qtbase = super.qt5.qtbase.overrideAttrs (oa: {
      NIX_CFLAGS_COMPILE = oa.NIX_CFLAGS_COMPILE + " -O2";
    });
  }
)

You can check what’s being used with

nix eval nixpkgs.qt5.qtbase.NIX_CFLAGS_COMPILE
3

I think I had tried this before. Here’s what I get:

$ sudo nix-instantiate '<nixpkgs/nixos>' -A system --show-trace
error: while evaluating the attribute 'activationScript' of the derivation 'nixos-system-illustris-thinkpad-20.09.2016.19db3e5ea27' at /nix/var/nix/profiles/per-user/root/channels/nixos/nixos/modules/system/activation/top-level.nix:95:5:
while evaluating the attribute 'system.activationScripts.script' at /nix/var/nix/profiles/per-user/root/channels/nixos/nixos/modules/system/activation/activation-script.nix:68:9:
while evaluating 'textClosureMap' at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/strings-with-deps.nix:70:35, called from /nix/var/nix/profiles/per-user/root/channels/nixos/nixos/modules/system/activation/activation-script.nix:89:18:
while evaluating 'id' at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/trivial.nix:14:5, called from undefined position:
while evaluating the attribute 'text' at /nix/var/nix/profiles/per-user/root/channels/nixos/nixos/modules/system/activation/activation-script.nix:9:5:
while evaluating the attribute 'text' at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/strings-with-deps.nix:77:38:
while evaluating the attribute 'sources' of the derivation 'etc' at /nix/var/nix/profiles/per-user/root/channels/nixos/nixos/modules/system/etc/etc.nix:12:5:
while evaluating anonymous function at /nix/var/nix/profiles/per-user/root/channels/nixos/nixos/modules/system/etc/etc.nix:20:20, called from undefined position:
while evaluating the attribute 'source' at undefined position:
while evaluating 'g' at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/attrsets.nix:276:19, called from undefined position:
while evaluating anonymous function at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/modules.nix:98:72, called from /nix/var/nix/profiles/per-user/root/channels/nixos/lib/attrsets.nix:279:20:
while evaluating the attribute 'value' at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/modules.nix:465:9:
while evaluating the option `environment.etc.dbus-1.source':
while evaluating the attribute 'mergedValue' at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/modules.nix:497:5:
while evaluating anonymous function at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/modules.nix:499:17, called from /nix/var/nix/profiles/per-user/root/channels/nixos/lib/modules.nix:499:12:
while evaluating 'check' at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/types.nix:256:15, called from /nix/var/nix/profiles/per-user/root/channels/nixos/lib/modules.nix:499:22:
while evaluating the attribute 'serviceDirectories' of the derivation 'dbus-1' at /nix/var/nix/profiles/per-user/root/channels/nixos/pkgs/build-support/trivial-builders.nix:7:7:
while evaluating anonymous function at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/types.nix:265:14, called from undefined position:
while evaluating the attribute 'value' at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/modules.nix:510:27:
while evaluating anonymous function at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/modules.nix:499:17, called from /nix/var/nix/profiles/per-user/root/channels/nixos/lib/modules.nix:499:12:
while evaluating 'check' at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/types.nix:256:15, called from /nix/var/nix/profiles/per-user/root/channels/nixos/lib/modules.nix:499:22:
while evaluating the attribute 'passAsFile' of the derivation 'system-path' at /nix/var/nix/profiles/per-user/root/channels/nixos/pkgs/build-support/trivial-builders.nix:7:7:
while evaluating the attribute 'out.outPath' at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/customisation.nix:156:13:
while evaluating the attribute 'buildInputs' of the derivation 'virt-manager-2.2.1' at /nix/var/nix/profiles/per-user/root/channels/nixos/pkgs/development/interpreters/python/mk-python-derivation.nix:108:5:
while evaluating the attribute 'propagatedBuildInputs' of the derivation 'spice-gtk-0.37' at /nix/var/nix/profiles/per-user/root/channels/nixos/pkgs/stdenv/generic/make-derivation.nix:192:11:
while evaluating the attribute 'buildInputs' of the derivation 'gst-plugins-good-1.16.2' at /nix/var/nix/profiles/per-user/root/channels/nixos/pkgs/stdenv/generic/make-derivation.nix:192:11:
while evaluating 'getOutput' at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/attrsets.nix:464:23, called from undefined position:
while evaluating anonymous function at /nix/var/nix/profiles/per-user/root/channels/nixos/pkgs/stdenv/generic/make-derivation.nix:143:17, called from undefined position:
while evaluating 'addMetaAttrs' at /nix/var/nix/profiles/per-user/root/channels/nixos/lib/meta.nix:15:28, called from /nix/var/nix/profiles/per-user/root/channels/nixos/pkgs/top-level/all-packages.nix:14107:12:
attribute 'callPackage' missing, at /nix/var/nix/profiles/per-user/root/channels/nixos/pkgs/top-level/all-packages.nix:18577:15

The line mentioned in the error is pkgs/top-level/all-packages.nix:18577:

v4l-utils = qt5.callPackage ../os-specific/linux/v4l-utils { };

I’m not sure if I’m understanding this correctly, but it looks like overriding qt5.qtbase removes callPackage in qt5.

qt5.callPackage also appears to be the same as callPackage

nix-repl> pkgs = import <nixpkgs> {}

nix-repl> pkgs.callPackage
«lambda @ /nix/var/nix/profiles/per-user/root/channels/nixos/lib/customisation.nix:117:31»

nix-repl> pkgs.qt5.callPackage
«lambda @ /nix/var/nix/profiles/per-user/root/channels/nixos/lib/customisation.nix:117:31»
4

Ah you’re right, maybe this will work?

(
  self: super: {
    qt5 = super.qt5 // {
      qtbase = super.qt5.qtbase.overrideAttrs (oa: {
        NIX_CFLAGS_COMPILE = oa.NIX_CFLAGS_COMPILE + " -O2";
      });
    };
  }
)

But if you’re modifying nixpkgs this extensively, it will probably be easier to use a modified nixpkgs directly rather than try to make the changes you need via overlays

5

Thanks! This made some progress.
Instead of appending O2 (which would be ignored in favor of the O3 already present), I replaced it with the value it would otherwise have

qt5 = super.qt5 //{
    qtbase = super.qt5.qtbase.overrideAttrs (oa: {
        NIX_CFLAGS_COMPILE = "-Wno-error=sign-compare -DNIXPKGS_QTCOMPOSE=\"/nix/store/myn5q5p002n997p2g19x4mf01cjwp1w2-libX11-1.6.12/share/X11/locale\" -DLIBRESOLV_SO=\"/nix/store/iz8q8dbqxkhsmjn9mf86wmrxj8bfpiyd-glibc-2.31/lib/libresolv\" -DN............. -march=skylake"
    });
};

This partially works. Now there are two instances of qtbase-5.15.0.drv, one with “-march=skylake -O3” and the other with “-march=skylake”.
The immediate parents of the O3 one are:

/nix/store/mcs6i4dz5pbgj787p4hj13k35dbmcxps-qtbase-5.15.0.drv
NAR Size: 15.07 KiB
Closure Size: 3.15 MiB
Immediate Parents (6): hook.drv, qtdeclarative-5.15.0.drv, qtsvg-5.15.0.drv, pinentry-1.1.0.drv, hook.drv, qtwayland-5.15.0.drv

and the one without O3:

/nix/store/0aj5qb08m7s2rwb05p24azafx64bw85h-qtbase-5.15.0.drv
NAR Size: 14.85 KiB
Closure Size: 3.15 MiB
Immediate Parents (1): rescuetime-2.16.3.1.drv

I think rescuetime is referring to qtbase in a different way than pinentry (added by programs.gnupg.agent.enable = true;) and other packages.

Also, by modifying nixpkgs do you mean editing /nix/var/nix/profiles/per-user/...?

6

I mean git cloning the nixpkgs repo, making the changes you need locally, and setting export NIX_PATH=nixpkgs=/path/to/your/checkout so that nix commands use your local clone instead of whatever channel you are currently using.