... at call sites that are may be in the hot path.
I do not know how clever the compiler gets at these sites.
My primary concern is to not regress performance and I am confident
that this achieves it the easy way.
Known behavior changes:
- `MemorySourceAccessor`'s comparison operators no longer forget to
compare the `SourceAccessor` base class.
Progress on #10832
What remains for that issue is hopefully much easier!
Progress on #5638
There are still a global fetcher and eval settings, but they are pushed
down into `libnixcmd`, which is a lot less bad a place for this sort of
thing.
Continuing process pioneered in
52bfccf8d8.
This improves the error message of nix-env -qa, among others, which
is crucial for understanding some ofborg eval error reports, such as
https://gist.github.com/GrahamcOfBorg/89101ca9c2c855d288178f1d3c78efef
After this change, it will report the same trace, but also start with
```
error:
… while evaluating the attribute 'devShellTools'
… while evaluating the attribute 'nixos'
… while evaluating the attribute 'docker-tools-nix-shell'
… while evaluating the attribute 'aarch64-darwin'
… from call site
at /home/user/h/nixpkgs/outpaths.nix:48:6:
47| tweak = lib.mapAttrs
48| (name: val:
| ^
49| if name == "recurseForDerivations" then true
<same>
```
move together all syntactic and semantic information into one
page, and add a page on data types, which in turn links to the syntax and
semantics.
also split out the note on scoping rules into its own page.
Co-authored-by: Ryan Hendrickson <ryan.hendrickson@alum.mit.edu>
The code that counts the number of elided attrs incorrectly used the
per-printer "global" attribute counter instead of a counter that
was relevant only to the current attribute set.
This bug flew under the radar because often the attribute sets aren't
nested, not big enough, or we wouldn't pay attention to the numbers.
I've noticed the issue because the difference underflowed.
Although this behavior is tested by the functional test
lang/eval-fail-bad-string-interpolation-4.nix, the underflow slipped
through review. A simpler reproducer would be as follows, but I
haven't added it to the test suite to keep it simple and marginally
faster.
```
$ nix run nix/2.23.1 -- eval --expr '"" + (let v = { a = { a = 1; b = 2; c = 1; d = 1; e = 1; f = 1; g = 1; h = 1; }; b = { a = 1; b = 1; c = 1; }; }; in builtins.deepSeq v v)'
error:
… while evaluating a path segment
at «string»:1:6:
1| "" + (let v = { a = { a = 1; b = 2; c = 1; d = 1; e = 1; f = 1; g = 1; h = 1; }; b = { a = 1; b = 1; c = 1; }; }; in builtins.deepSeq v v)
| ^
error: cannot coerce a set to a string: { a = { a = 1; b = 2; c = 1; d = 1; e = 1; f = 1; g = 1; h = 1; }; b = { a = 1; «4294967289 attributes elided» }; }
```
We don't apply any patches to it, and vendoring it locks users into
bugs (it hasn't been updated since its introduction in late 2021).
Closes https://git.lix.systems/lix-project/lix/issues/164
Change-Id: Ied071c841fc30b0dfb575151afd1e7f66970fdb9
(cherry picked from commit 80405d06264f0de1c16ee2646388ab501df20628)
