Got infinite recursion encountered when accessing self.outPath in a flake

[Atry]

Describe the bug

When accessing self.outPath in flake outputs function body, I got infinite recursion encountered.
Steps To Reproduce

1. create the following flake.nix

   {
     outputs = { self, ... }: builtins.trace self.outPath {
       packages = {};
     };
   }

2. nix flake show
3. Error error: infinite recursion encountered

Expected behavior

No error

nix-env --version output

nix-env (Nix) 2.15.0

Additional context

Workaround:

{
  outputs = { self, ... }: {
    packages = builtins.trace self.outPath {};
  };
}

nix flake show works as expected.

Priorities

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[roberth]

This can be further reduced to

# simplified
let
callFlakeOutputs = f:
  let
    self = outputs // sourceInfo;
    outputs = f { inherit self; };
  in
    self;
sourceInfo = { outPath = ./.; };

in
callFlakeOutputs ({ self, ... }: builtins.trace self.outPath {
  foo = true;
})

which then reduces to

let self = builtins.trace self.outPath { } // { outPath = ./.; }; in self

where you can see that in order to evaluate self, we first have to pull outPath from self, which can't be done yet.

This could be solved by

• [WIP] Lazy attribute names #4154

I'll close this as a duplicate of

• Lazy attribute names #4090.