Mention BLAKE3 in the Nix 2.27 release notes

`CONTENT_ADDRESSED` -> `NIX_TESTS_CA_BY_DEFAULT`

Now, both the unit and functional tests relating to derivation options
are tested both ways -- with input addressing and content-addressing
derivations.

Tests are updated accordingly.

This moves us towards getting rid of `ParsedDerivation` and just having
`DerivationOptions`.

Co-Authored-By: HaeNoe <[email protected]>

Only a much smaller `StructuredAttrs` remains, the rest is is now moved
to `DerivationOptions`.

This gets us quite close to `std::optional<StructuredAttrs>` and
`DerivationOptions` being included in `Derivation` as fields.

This requires that we refer to the `sourceInfo` instead of the
`result`. However, `sourceInfo` does not create a chain of basedir
resolution, so we add that back with `flakeDir`.

Test derivation options with content-addressing too

…s-exportReferencesGraph

Move `exportReferencesGraph` to `DerivationOptions`

Rename FlakeCache to InputCache and move it to libfetchers

Fix issue NixOS#13018, `sourceInfo` strict in `outputs`

…alues

We had fields set to the same values before in our test data. This is
not a problem per-se, but does mean we wouldn't catch certain mixups.
Now, the fields are set to distinct values (where possible), which makes
the test more robust.

This was almost a bug! It wasn't simply because another assignment would
clobber it later.

Scrap `ParsedDerivation` for parts

libexpr: fix UB in builtins.ceil and builtins.floor

Improve derivation "advanced attrs" test, fix almost-bug

The other parameters it took were somewhat implementation-specific.

This is unreleated to the other commits in this PR.

Now, most of it is in two new functions:
`LocalDerivationGoal::{,un}repareBuild`.

This might seems like a step backwards from coroutines --- now we have
more functions, and are stuck with class vars --- but I don't think it
needs to be.

There's a few options here:

- (Re)introduce coroutines for the isolated building logic. We could use the
  same coroutines types, or simpler ones specialized to this use-case.
  The `tryLocalBuild` caller can still use `Goal::Co`, and just will
  manually "pump" this inner coroutine.

- Return closures from each step. This is sort of like coroutines by
  hand, but it still allows us to stop writing down the local variables
  in each type.

  Being able to fully-use RAII again would be very nice!

- Keep top-level first-order functions like now, but make more
  functional. Instead of having one state object (`DerivationBuilder`)
  for all steps (setup, run, teardown), we can have separate structs for
  the live variables at each point we consume and return.

  This at least avoids "are these variables active at this time?"
  questions, but doesn't give us the full benefit of RAII as we must
  manually ensure FIFO create/destroy orders still.

One thing to note is that by keeping the `outputLock` unlocking in
`tryLocalBuild`, we are arguably uncovering a rebuild scheduling vs
building distinction, as the output locks are pretty squarely a
scheduling concern. It's nice that the builder doesn't need to know
about them at all.

We have a new `DerivationBuilder` struct, and `DerivationBuilderParams`
`DerivationBuilderCallbacks` supporting it.

`LocalDerivationGoal` doesn't subclass any of these, so we are ready to
now move them out to a new file!

…goal-encapsulation

Separate derivation building from the scheduler

This is done to prior to splitting, just like
05cc5a8 for
68f4c72.

The building logic is now free of the scheduling logic!

(The interface between them is just what is in the new header. This
makes it much easier to audit, and shrink over time.)

It seems reasonable to add both `$HOME/.profile/bin` and
`@localstatedir@/nix/profiles/default/bin` to `$PATH` for both user
local and daemon based nix execution.  Nix daemon execution mode does
not affect these path.

There seems to be no good reason for `nix-profile.fish` to set
`$MANPATH` while it being unset when `nix-profile-daemon.fish` is used.

While it seems unlikely that `$USER` will be unset while `$HOME` is set,
as `$USER` is not used in the script and as `nix-profile-daemon.fish` is
not checking `$USER`, it seems better to remove this check.

`nix-profile.fish` and `nix-profile-daemon.fish` now become identical.

…st-USER

nix-profile.fish: Do not check $USER

In rendered form:

```diff
-Add references to the manual using ..
+Add references to the manual using [links like this](@docroot@/example.md)
```

(cherry picked from commit 147a34c)

…/pr-13221

doc: Render verbatim `@docroot@` on contributing page (backport NixOS#13221)

Need to investigate why store->getFSAccessor() breaks a test.

This reduces the closure size on master by 40MiB.

```
$ nix build github:nixos/nix/1e822bd4149a8bce1da81ee2ad9404986b07914c#nix-store --out-link closure-on-master
$ nix build .#nix-store -L --out-link closure-without-icu
$ nix path-info --closure-size -h ./closure-on-master
/nix/store/8gwr38m5h6p7245ji9jv28a2a11w1isx-nix-store-2.29.0pre  124.4 MiB
$ nix path-info --closure-size -h ./closure-without-icu
/nix/store/k0gwfykjqpnmaqbwh23nk55lhanc9g24-nix-store-2.29.0pre   86.6 MiB
```

(cherry picked from commit f3090ef)

(cherry picked from commit 18a5589)

…/pr-13142

libstore: Use `boost::regex` for GC root discovery (backport NixOS#13142)