BTW, rest of Nixpkgs follows the convention that binaries are in the first output which libsForQt5 doesn't seem to follow. It probably should.

(Also path to pam_kwallet5.so needs to be fixed then :)

BTW, rest of Nixpkgs follows the convention that binaries are in the first output which libsForQt5 doesn't seem to follow. It probably should.

Is this policy stated anywhere? If Qt-based packages complied with this policy, we could no longer put binaries in their own output. (Qt libraries must go in the first output.)

https://nixos.org/nixpkgs/manual/#idm140737318570400

By convention, the first output should contain the executable programs provided by the package as that output is used by Nix in string conversions, allowing references to binaries like ${pkgs.perl}/bin/perl to always work.

OK, I will have to go through and remove the bin outputs from every package using Qt.

@benley I will merge this as-is to fix the problem, but it will be shortly obsolete anyway.

Can you describe in what way Qt assumes that libraries are in the first output, and why that assumption can't be fixed instead?

Can you describe in what way Qt assumes that libraries are in the first output, and why that assumption can't be fixed instead?

The last time I tried this was while multiple-outputs was still unmerged; the situation may have changed. Qt tends to remember paths used during the build by encoding them as strings in the library being built. Something about the first output causes it to always be remembered. If the first output is bin, and the libraries are in out, then there is a dependency cycle: binaries in bin have out in their RPATH and libraries in out have bin in their data sections because of some weird Qt thing.

There are probably ways to mitigate this (nukeReferences?) but I am hesitant to do that because I never really understood what was going on. Or, maybe we can show this is no longer a problem.

Yes I'm pretty sure things have changed since then. This is basically the only code in stdenv builder that cares about the first output:

176     local propagaterOutput="$outputDev"
177     if [ -z "$propagaterOutput" ]; then
178         propagaterOutput="$outputFirst"
179     fi

where outputDev is initialized to either "$dev" or "$out":

32 _overrideFirst outputDev "dev" "out"

(it's also dead code I think, since the stdenv builder explodes in other ways if there is no out output, so no matter what outputDev will be initialized).

Also I did get a clean compile of kwallet with this change (though of course that doesn't seem to be everything):

diff --git a/pkgs/development/libraries/kde-frameworks/default.nix b/pkgs/development/libraries/kde-frameworks/default.nix
index d5995459fd..51b8140def 100644
--- a/pkgs/development/libraries/kde-frameworks/default.nix
+++ b/pkgs/development/libraries/kde-frameworks/default.nix
@@ -78,7 +78,7 @@ let
             inherit (args) name;
             inherit (srcs."${name}") src version;
 
-            outputs = args.outputs or [ "out" "dev" "bin" ];
+            outputs = args.outputs or [ "bin" "dev" "out" ];
             hasBin = lib.elem "bin" outputs;
             hasDev = lib.elem "dev" outputs;