forked from lix-project/lix
Rebecca Turner
9e7e927837
Previously, errors while printing values in `nix repl` would be printed
in `«error: ...»` brackets rather than displayed normally:
```
nix-repl> legacyPackages.aarch64-darwin.pythonPackages.APScheduler
«error: Package ‘python-2.7.18.7’ in /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/pkgs/development/interpreters/python/cpython/2.7/default.nix:335 is marked as insecure, refusing to evaluate.»
```
Now, errors will be displayed normally if they're emitted at the
top-level of an expression:
```
nix-repl> legacyPackages.aarch64-darwin.pythonPackages.APScheduler
error:
… in the condition of the assert statement
at /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/lib/customisation.nix:268:17:
267| in commonAttrs // {
268| drvPath = assert condition; drv.drvPath;
| ^
269| outPath = assert condition; drv.outPath;
… in the left operand of the OR (||) operator
at /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/pkgs/development/interpreters/python/passthrufun.nix:28:45:
27| if lib.isDerivation value then
28| lib.extendDerivation (valid value || throw "${name} should use `buildPythonPackage` or `toPythonModule` if it is to be part of the Python packages set.") {} value
| ^
29| else
(stack trace truncated; use '--show-trace' to show the full trace)
error: Package ‘python-2.7.18.7’ in /nix/store/6s0m1qc31zw3l3kq0q4wd5cp3lqpkq0q-source/pkgs/development/interpreters/python/cpython/2.7/default.nix:335 is marked as insecure, refusing to evaluate.
```
Errors emitted in nested structures (like e.g. when printing `nixpkgs`)
will still be printed in brackets.
Change-Id: I25aeddf08c017582718cb9772a677bf51b9fc2ad
41 lines
1 KiB
Markdown
41 lines
1 KiB
Markdown
---
|
|
synopsis: Concise error printing in `nix repl`
|
|
prs: 9928
|
|
cls: 811
|
|
---
|
|
|
|
Previously, if an element of a list or attribute set threw an error while
|
|
evaluating, `nix repl` would print the entire error (including source location
|
|
information) inline. This output was clumsy and difficult to parse:
|
|
|
|
```
|
|
nix-repl> { err = builtins.throw "uh oh!"; }
|
|
{ err = «error:
|
|
… while calling the 'throw' builtin
|
|
at «string»:1:9:
|
|
1| { err = builtins.throw "uh oh!"; }
|
|
| ^
|
|
|
|
error: uh oh!»; }
|
|
```
|
|
|
|
Now, only the error message is displayed, making the output much more readable.
|
|
```
|
|
nix-repl> { err = builtins.throw "uh oh!"; }
|
|
{ err = «error: uh oh!»; }
|
|
```
|
|
|
|
However, if the whole expression being evaluated throws an error, source
|
|
locations and (if applicable) a stack trace are printed, just like you'd expect:
|
|
|
|
```
|
|
nix-repl> builtins.throw "uh oh!"
|
|
error:
|
|
… while calling the 'throw' builtin
|
|
at «string»:1:1:
|
|
1| builtins.throw "uh oh!"
|
|
| ^
|
|
|
|
error: uh oh!
|
|
```
|