Commit graph

15 commits

Author SHA1 Message Date
pennae
c9fc975259 optimize removeAttrs builtin
use a sorted array of symbols to be removed instead of a set. this saves a lot
of memory allocations and slightly speeds up removal.
2022-01-14 14:01:52 +01:00
Eelco Dolstra
2b4c944823 Remove EvalState::mkAttrs() 2022-01-04 20:29:17 +01:00
Eelco Dolstra
6d9a6d2cc3 Ensure that attrsets are sorted
Previously you had to remember to call value->attrs->sort() after
populating value->attrs. Now there is a BindingsBuilder helper that
wraps Bindings and ensures that sort() is called before you can use
it.
2022-01-04 18:00:33 +01:00
Robert Hensing
f10465774f Force all Pos* to be non-null
This fixes a class of crashes and introduces ptr<T> to make the
code robust against this failure mode going forward.

Thanks regnat for the idea of a ref<T> without overhead!

Closes #4895
Closes #4893
Closes #5127
Closes #5113
2021-08-29 18:11:58 +02:00
Maximilian Bosch
7c76964daa
libexpr: misc improvements for proper error position
When working on some more complex Nix code, there are sometimes rather
unhelpful or misleading error messages, especially if coerce-errors are
thrown.

This patch is a first steps towards improving that. I'm happy to file
more changes after that, but I'd like to gather some feedback first.

To summarize, this patch does the following things:

* Attrsets (a.k.a. `Bindings` in `libexpr`) now have a `Pos`. This is
  helpful e.g. to identify which attribute-set in `listToAttrs` is
  invalid.

* The `Value`-struct has a new method named `determinePos` which tries
  to guess the position of a value and falls back to a default if that's
  not possible.

  This can be used to provide better messages if a coercion fails.

* The new `determinePos`-API is used by `builtins.concatMap` now. With
  that change, Nix shows the exact position in the error where a wrong
  value was returned by the lambda.

  To make sure it's still obvious that `concatMap` is the problem,
  another stack-frame was added.

* The changes described above can be added to every other `primop`, but
  first I'd like to get some feedback about the overall approach.
2021-04-13 23:12:38 +02:00
Eelco Dolstra
8d4268d190 Improve error formatting
Changes:

* The divider lines are gone. These were in practice a bit confusing,
  in particular with --show-trace or --keep-going, since then there
  were multiple lines, suggesting a start/end which wasn't the case.

* Instead, multi-line error messages are now indented to align with
  the prefix (e.g. "error: ").

* The 'description' field is gone since we weren't really using it.

* 'hint' is renamed to 'msg' since it really wasn't a hint.

* The error is now printed *before* the location info.

* The 'name' field is no longer printed since most of the time it
  wasn't very useful since it was just the name of the exception (like
  EvalError). Ideally in the future this would be a unique, easily
  googleable error ID (like rustc).

* "trace:" is now just "…". This assumes error contexts start with
  something like "while doing X".

Example before:

  error: --- AssertionError ---------------------------------------------------------------------------------------- nix
  at: (7:7) in file: /home/eelco/Dev/nixpkgs/pkgs/applications/misc/hello/default.nix

       6|
       7|   x = assert false; 1;
        |       ^
       8|

  assertion 'false' failed
  ----------------------------------------------------- show-trace -----------------------------------------------------
  trace: while evaluating the attribute 'x' of the derivation 'hello-2.10'
  at: (192:11) in file: /home/eelco/Dev/nixpkgs/pkgs/stdenv/generic/make-derivation.nix

     191|         // (lib.optionalAttrs (!(attrs ? name) && attrs ? pname && attrs ? version)) {
     192|           name = "${attrs.pname}-${attrs.version}";
        |           ^
     193|         } // (lib.optionalAttrs (stdenv.hostPlatform != stdenv.buildPlatform && !dontAddHostSuffix && (attrs ? name || (attrs ? pname && attrs ? version)))) {

Example after:

  error: assertion 'false' failed

         at: (7:7) in file: /home/eelco/Dev/nixpkgs/pkgs/applications/misc/hello/default.nix

              6|
              7|   x = assert false; 1;
               |       ^
              8|

         … while evaluating the attribute 'x' of the derivation 'hello-2.10'

         at: (192:11) in file: /home/eelco/Dev/nixpkgs/pkgs/stdenv/generic/make-derivation.nix

            191|         // (lib.optionalAttrs (!(attrs ? name) && attrs ? pname && attrs ? version)) {
            192|           name = "${attrs.pname}-${attrs.version}";
               |           ^
            193|         } // (lib.optionalAttrs (stdenv.hostPlatform != stdenv.buildPlatform && !dontAddHostSuffix && (attrs ? name || (attrs ? pname && attrs ? version)))) {
2021-01-21 11:02:09 +01:00
Ben Burdette
1d43a6e123 use plain errPos instead of nixCode; fix tests 2020-06-23 15:30:13 -06:00
Eelco Dolstra
1fb762d11f Get rid of explicit ErrorInfo constructors 2020-06-15 14:06:58 +02:00
Ben Burdette
55eb717148 add pos to errorinfo, remove from hints 2020-05-08 18:18:28 -06:00
Eelco Dolstra
9af10b753c Bindings::get(): std::optional<Attr *> -> Attr *
Returning a nullable type in an optional is silly.
2020-02-13 17:15:05 +01:00
Eelco Dolstra
79142cbbe1 Bindings: Add convenience method for requiring an attribute
(cherry picked from commit fb692e5f7b)
2019-12-05 20:29:15 +01:00
Eelco Dolstra
0d118ef0c9 Bindings::get(): Add convenience method
This allows writing attribute lookups as

    if (auto name = value.attrs->get(state.sName))
      ...

(cherry picked from commit f216c76c56)
2019-12-05 20:29:00 +01:00
Tuomas Tynkkynen
056d28a601 libexpr: Don't create lots of temporary strings in Bindings::lexicographicOrder
Avoids ~180,000 string temporaries created when evaluating a headless
NixOS system.
2018-02-19 22:47:25 +02:00
Eelco Dolstra
54801ed6ad
Bindings: Add a method for iterating in lexicographically sorted order 2017-01-26 20:40:33 +01:00
Nicolas B. Pierron
db21cfa688 Move attribute set data structures into their own header file.
This modification moves Attr and Bindings structures into their own header
file which is dedicated to the attribute set representation. The goal of to
isolate pieces of code which are related to the attribute set
representation. Thus future modifications of the attribute set
representation will only have to modify these files, and not every other
file across the evaluator.
2015-07-14 19:23:17 +02:00