Commit graph

3 commits

Author SHA1 Message Date
Rebecca Turner
c6a89c1a16
libexpr: Support structured error classes
While preparing PRs like #9753, I've had to change error messages in
dozens of code paths. It would be nice if instead of

    EvalError("expected 'boolean' but found '%1%'", showType(v))

we could write

    TypeError(v, "boolean")

or similar. Then, changing the error message could be a mechanical
refactor with the compiler pointing out places the constructor needs to
be changed, rather than the error-prone process of grepping through the
codebase. Structured errors would also help prevent the "same" error
from having multiple slightly different messages, and could be a first
step towards error codes / an error index.

This PR reworks the exception infrastructure in `libexpr` to
support exception types with different constructor signatures than
`BaseError`. Actually refactoring the exceptions to use structured data
will come in a future PR (this one is big enough already, as it has to
touch every exception in `libexpr`).

The core design is in `eval-error.hh`. Generally, errors like this:

    state.error("'%s' is not a string", getAttrPathStr())
      .debugThrow<TypeError>()

are transformed like this:

    state.error<TypeError>("'%s' is not a string", getAttrPathStr())
      .debugThrow()

The type annotation has moved from `ErrorBuilder::debugThrow` to
`EvalState::error`.
2024-02-01 16:39:38 -08:00
Rebecca Turner
5cb98095ba
Remove some blank lines from stack traces
This keeps hint messages, source location information, and source code
snippets grouped together, while making stack traces shorter (so that
more stack frames can be viewed on the same terminal).

Before:

    error:
           … while evaluating the attribute 'body'

             at /Users/wiggles/nix/tests/functional/lang/eval-fail-assert.nix:4:3:

                3|
                4|   body = x "x";
                 |   ^
                5| }

           … from call site

             at /Users/wiggles/nix/tests/functional/lang/eval-fail-assert.nix:4:10:

                3|
                4|   body = x "x";
                 |          ^
                5| }

           … while calling 'x'

             at /Users/wiggles/nix/tests/functional/lang/eval-fail-assert.nix:2:7:

                1| let {
                2|   x = arg: assert arg == "y"; 123;
                 |       ^
                3|

           error: assertion '(arg == "y")' failed

           at /Users/wiggles/nix/tests/functional/lang/eval-fail-assert.nix:2:12:

                1| let {
                2|   x = arg: assert arg == "y"; 123;
                 |            ^
                3|

After:

    error:
           … while evaluating the attribute 'body'
             at /Users/wiggles/nix/tests/functional/lang/eval-fail-assert.nix:4:3:
                3|
                4|   body = x "x";
                 |   ^
                5| }

           … from call site
             at /Users/wiggles/nix/tests/functional/lang/eval-fail-assert.nix:4:10:
                3|
                4|   body = x "x";
                 |          ^
                5| }

           … while calling 'x'
             at /Users/wiggles/nix/tests/functional/lang/eval-fail-assert.nix:2:7:
                1| let {
                2|   x = arg: assert arg == "y"; 123;
                 |       ^
                3|

           error: assertion '(arg == "y")' failed
           at /Users/wiggles/nix/tests/functional/lang/eval-fail-assert.nix:2:12:
                1| let {
                2|   x = arg: assert arg == "y"; 123;
                 |            ^
                3|
2023-12-15 23:57:26 -08:00
John Ericson
68c81c7375 Put functional tests in tests/functional
I think it is bad for these reasons when `tests/` contains a mix of
functional and integration tests

 - Concepts is harder to understand, the documentation makes a good
   unit vs functional vs integration distinction, but when the
   integration tests are just two subdirs within `tests/` this is not
   clear.

 - Source filtering in the `flake.nix` is more complex. We need to
   filter out some of the dirs from `tests/`, rather than simply pick
   the dirs we want and take all of them. This is a good sign the
   structure of what we are trying to do is not matching the structure
   of the files.

With this change we have a clean:
```shell-session
$ git show 'HEAD:tests'
tree HEAD:tests

functional/
installer/
nixos/
```
2023-10-06 09:05:56 -04:00
Renamed from tests/lang/eval-fail-toJSON.err.exp (Browse further)