0: while evaluating the attribute 'python311.pythonForBuild.pkgs'
  0x600001522598
  ```

  After:

  ```
  0: while evaluating the attribute 'python311.pythonForBuild.pkgs'
  /nix/store/hg65h51xnp74ikahns9hyf3py5mlbbqq-source/overrides/default.nix:132:27

     131|
     132|       bootstrappingBase = pkgs.${self.python.pythonAttr}.pythonForBuild.pkgs;
        |                           ^
     133|     in
  ```

- The `--debugger` will start more reliably in `let` expressions and function calls [#6649](https://github.com/NixOS/nix/issues/6649) [#9917](https://github.com/NixOS/nix/pull/9917)

  Previously, if you attempted to evaluate this file with the debugger:

  ```nix
  let
    a = builtins.trace "before inner break" (
      builtins.break "hello"
    );
    b = builtins.trace "before outer break" (
      builtins.break a
    );
  in
    b
  ```

  Nix would correctly enter the debugger at `builtins.break a`, but if you asked
  it to `:continue`, it would skip over the `builtins.break "hello"` expression
  entirely.

  Now, Nix will correctly enter the debugger at both breakpoints.

- Nested debuggers are no longer supported [#9920](https://github.com/NixOS/nix/pull/9920)

  Previously, evaluating an expression that throws an error in the debugger would
  enter a second, nested debugger:

  ```
  nix-repl> builtins.throw "what"
  error: what


  Starting REPL to allow you to inspect the current state of the evaluator.

  Welcome to Nix 2.18.1. Type :? for help.

  nix-repl>
  ```

  Now, it just prints the error message like `nix repl`:

  ```
  nix-repl> builtins.throw "what"
  error:
         … while calling the 'throw' builtin
           at «string»:1:1:
              1| builtins.throw "what"
               | ^

         error: what
  ```

- Consistent order of function arguments in printed expressions [#9874](https://github.com/NixOS/nix/pull/9874)

  Function arguments are now printed in lexicographic order rather than the internal, creation-time based symbol order.

- Fix duplicate attribute error positions for `inherit` [#9874](https://github.com/NixOS/nix/pull/9874)

  When an `inherit` caused a duplicate attribute error the position of the error was not reported correctly, placing the error with the inherit itself or at the start of the bindings block instead of the offending attribute name.

- `inherit (x) ...` evaluates `x` only once [#9847](https://github.com/NixOS/nix/pull/9847)

  `inherit (x) a b ...` now evaluates the expression `x` only once for all inherited attributes rather than once for each inherited attribute.
  This does not usually have a measurable impact, but side-effects (such as `builtins.trace`) would be duplicated and expensive expressions (such as derivations) could cause a measurable slowdown.

- Store paths are allowed to start with `.` [#912](https://github.com/NixOS/nix/issues/912) [#9091](https://github.com/NixOS/nix/pull/9091) [#9095](https://github.com/NixOS/nix/pull/9095) [#9120](https://github.com/NixOS/nix/pull/9120) [#9121](https://github.com/NixOS/nix/pull/9121) [#9122](https://github.com/NixOS/nix/pull/9122) [#9130](https://github.com/NixOS/nix/pull/9130) [#9219](https://github.com/NixOS/nix/pull/9219) [#9224](https://github.com/NixOS/nix/pull/9224) [#9867](https://github.com/NixOS/nix/pull/9867)

  Leading periods were allowed by accident in Nix 2.4. The Nix team has considered this to be a bug, but this behavior has since been relied on by users, leading to unnecessary difficulties.
  From now on, leading periods are supported. The names `.` and `..` are disallowed, as well as those starting with `.-` or `..-`.

  Nix versions that denied leading periods are documented [in the issue](https://github.com/NixOS/nix/issues/912#issuecomment-1919583286).