14bf54bd39
Turns errors like:
let
somepkg.src = throw "invalid foobar";
in somepkg.src.meta
error:
… while evaluating the attribute 'src.meta'
at «string»:2:3:
1| let
2| somepkg.src = throw "invalid foobar";
| ^
3| in somepkg.src.meta
… while calling the 'throw' builtin
at «string»:2:17:
1| let
2| somepkg.src = throw "invalid foobar";
| ^
3| in somepkg.src.meta
error: invalid foobar
into errors like:
let
somepkg.src = throw "invalid foobar";
in somepkg.src.meta
error:
… while evaluating the attribute 'src.meta'
at «string»:2:3:
1| let
2| somepkg.src = throw "invalid foobar";
| ^
3| in somepkg.src.meta
… while evaluating 'somepkg.src' to select 'meta' on it
at «string»:3:4:
2| somepkg.src = throw "invalid foobar";
3| in somepkg.src.meta
| ^
… while calling the 'throw' builtin
at «string»:2:17:
1| let
2| somepkg.src = throw "invalid foobar";
| ^
3| in somepkg.src.meta
error: invalid foobar
And for type errors, from:
let
somepkg.src = "I'm not an attrset";
in somepkg.src.meta
error:
… while evaluating the attribute 'src.meta'
at «string»:2:3:
1| let
2| somepkg.src = "I'm not an attrset";
| ^
3| in somepkg.src.meta
… while selecting an attribute
at «string»:3:4:
2| somepkg.src = "I'm not an attrset";
3| in somepkg.src.meta
| ^
error: expected a set but found a string: "I'm not an attrset"
into:
let
somepkg.src = "I'm not an attrset";
in somepkg.src.meta
error:
… while evaluating the attribute 'src.meta'
at «string»:2:3:
1| let
2| somepkg.src = "I'm not an attrset";
| ^
3| in somepkg.src.meta
… while selecting 'meta' on 'somepkg.src'
at «string»:3:4:
2| somepkg.src = "I'm not an attrset";
3| in somepkg.src.meta
| ^
error: expected a set but found a string: "I'm not an attrset"
For the low price of an enumerate() and a lambda you too can have the
incorrect line of code actually show up in the trace!
Change-Id: Ic1491c86e33c167891bdac9adad6224784760bd6
90 lines
4.4 KiB
Markdown
90 lines
4.4 KiB
Markdown
---
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synopsis: "Trace which part of a `foo.bar.baz` expression errors"
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cls: 1505, 1506
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credits: Qyriad
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category: Improvements
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---
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Previously, if an attribute path selection expression like `linux_4_9.meta.description` it wouldn't show you which one of those parts in the attribute path, or even that that line of code is what caused evaluation of the failing expression.
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The previous error looks like this:
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```
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pkgs.linuxKernel.kernels.linux_4_9.meta.description
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error:
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… while evaluating the attribute 'linuxKernel.kernels.linux_4_9.meta.description'
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at /nix/store/dk2rpyb6ndvfbf19bkb2plcz5y3k8i5v-source/pkgs/top-level/linux-kernels.nix:278:5:
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277| } // lib.optionalAttrs config.allowAliases {
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278| linux_4_9 = throw "linux 4.9 was removed because it will reach its end of life within 22.11";
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| ^
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279| linux_4_14 = throw "linux 4.14 was removed because it will reach its end of life within 23.11";
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… while calling the 'throw' builtin
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at /nix/store/dk2rpyb6ndvfbf19bkb2plcz5y3k8i5v-source/pkgs/top-level/linux-kernels.nix:278:17:
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277| } // lib.optionalAttrs config.allowAliases {
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278| linux_4_9 = throw "linux 4.9 was removed because it will reach its end of life within 22.11";
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| ^
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279| linux_4_14 = throw "linux 4.14 was removed because it will reach its end of life within 23.11";
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error: linux 4.9 was removed because it will reach its end of life within 22.11
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```
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Now, the error will look like this:
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```
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pkgs.linuxKernel.kernels.linux_4_9.meta.description
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error:
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… while evaluating the attribute 'linuxKernel.kernels.linux_4_9.meta.description'
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at /nix/store/dk2rpyb6ndvfbf19bkb2plcz5y3k8i5v-source/pkgs/top-level/linux-kernels.nix:278:5:
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277| } // lib.optionalAttrs config.allowAliases {
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278| linux_4_9 = throw "linux 4.9 was removed because it will reach its end of life within 22.11";
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| ^
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279| linux_4_14 = throw "linux 4.14 was removed because it will reach its end of life within 23.11";
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… while evaluating 'pkgs.linuxKernel.kernels.linux_4_9' to select 'meta' on it
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at «string»:1:1:
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1| pkgs.linuxKernel.kernels.linux_4_9.meta.description
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| ^
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… caused by explicit throw
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at /nix/store/dk2rpyb6ndvfbf19bkb2plcz5y3k8i5v-source/pkgs/top-level/linux-kernels.nix:278:17:
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277| } // lib.optionalAttrs config.allowAliases {
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278| linux_4_9 = throw "linux 4.9 was removed because it will reach its end of life within 22.11";
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| ^
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279| linux_4_14 = throw "linux 4.14 was removed because it will reach its end of life within 23.11";
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error: linux 4.9 was removed because it will reach its end of life within 22.11
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```
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Not only does the line of code that referenced the failing attribute show up in the trace, it also tells you that it was specifically the `linux_4_9` part that failed.
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This includes if the failing part is a top-level binding:
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```
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let
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inherit (pkgs.linuxKernel.kernels) linux_4_9;
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in linux_4_9.meta.description
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error:
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… while evaluating 'linux_4_9' to select 'meta.description' on it
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at «string»:3:4:
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2| inherit (pkgs.linuxKernel.kernels) linux_4_9;
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3| in linux_4_9.meta.description
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| ^
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… while evaluating the attribute 'linux_4_9'
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at /nix/store/dk2rpyb6ndvfbf19bkb2plcz5y3k8i5v-source/pkgs/top-level/linux-kernels.nix:278:5:
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277| } // lib.optionalAttrs config.allowAliases {
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278| linux_4_9 = throw "linux 4.9 was removed because it will reach its end of life within 22.11";
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| ^
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279| linux_4_14 = throw "linux 4.14 was removed because it will reach its end of life within 23.11";
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… caused by explicit throw
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at /nix/store/dk2rpyb6ndvfbf19bkb2plcz5y3k8i5v-source/pkgs/top-level/linux-kernels.nix:278:17:
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277| } // lib.optionalAttrs config.allowAliases {
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278| linux_4_9 = throw "linux 4.9 was removed because it will reach its end of life within 22.11";
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| ^
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279| linux_4_14 = throw "linux 4.14 was removed because it will reach its end of life within 23.11";
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error: linux 4.9 was removed because it will reach its end of life within 22.11
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```
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