internal-json logger improvements: dedicated error types for failed drv builds vs. nix evaluation error

[qknight]

Is your feature request related to a problem?

Using the internal-json there is no clear concept if the error is a nix evaluation error or a mkDerivation error, like a rustc error related to the rust lanauge.

mkDerivation installPhase error:

@nix {"action":"msg","column":null,"file":null,"level":0,"line":null,"msg":"\u001b[31;1merror:\u001b[0m \u001b[0mbuilder for '\u001b[35;1m/nix/store/0y0jz1i6sia87lh1z70g0b8w8737imb9-asdf-b.drv\u001b[0m' failed with exit code 1;\n       last 1 log lines:\n       > Running phase: installPhase\n       For full logs, run:\n         \u001b[1mnix log /nix/store/0y0jz1i6sia87lh1z70g0b8w8737imb9-asdf-b.drv\u001b[0m","raw_msg":"\u001b[0mbuilder for '\u001b[35;1m/nix/store/0y0jz1i6sia87lh1z70g0b8w8737imb9-asdf-b.drv\u001b[0m' failed with exit code 1;\nlast 1 log lines:\n> Running phase: installPhase\nFor full logs, run:\n  \u001b[1mnix log /nix/store/0y0jz1i6sia87lh1z70g0b8w8737imb9-asdf-b.drv\u001b[0m"}

nix syntax error:

nix build --file default.nix -L --keep-going --log-format internal-json
@nix {"action":"msg","column":3,"file":"/home/nixos/cargo/default.nix:4:3","level":0,"line":4,"msg":"\u001b[31;1merror:\u001b[0m syntax error, unexpected ID, expecting '.' or '='\n       \u001b[34;1mat \u001b[35;1m/home/nixos/cargo/default.nix:4:3\u001b[0m:\n            3| asdf\n            4|   b = pkgs.stdenv.mkDerivation {\n             |   \u001b[31;1m^\u001b[0m\n            5|   name=\"asdf b\";","raw_msg":"syntax error, unexpected ID, expecting '.' or '='"}

Proposed solution

As mentioned in #13909

• it would be helpful to know error codes, i.e. to know if it is a nix evaluation error or a mkDerivation internal error.
• Ideally pin nix build to "id": 0 and merge the output message with: @nix {"action":"stop","id":0, "code": 0}. This would probably be the last message in the json stream.

"code" could be:

• 0: no error
• 1: nix error
• 2: one or more mkDerivation error(s)

Additional context

For my current libnix project: Integrating nix into cargo build I can only guess that if "file": null is given it was not a nix error. It would be helpful if this "action":"msg" would be merged into @nix {"action":"stop","id":0} which does not exist yet.

Checklist

• checked latest Nix manual (source)
• checked open feature issues and pull requests for possible duplicates

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