Age | Commit message (Collapse) | Author |
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Already, we had classes like `BuiltPathsCommand` and `StorePathsCommand`
which provided alternative `run` virtual functions providing the
implementation with more arguments. This was a very nice and easy way to
make writing command; just fill in the virtual functions and it is
fairly clear what to do.
However, exception to this pattern were `Installable{,s}Command`. These
two classes instead just had a field where the installables would be
stored, and various side-effecting `prepare` and `load` machinery too
fill them in. Command would wish out those fields.
This isn't so clear to use.
What this commit does is make those command classes like the others,
with richer `run` functions.
Not only does this restore the pattern making commands easier to write,
it has a number of other benefits:
- `prepare` and `load` are gone entirely! One command just hands just
hands off to the next.
- `useDefaultInstallables` because `defaultInstallables`. This takes
over `prepare` for the one case that needs it, and provides enough
flexiblity to handle `nix repl`'s idiosyncratic migration.
- We can use `ref` instead of `std::shared_ptr`. The former must be
initialized (so it is like Rust's `Box` rather than `Option<Box>`,
This expresses the invariant that the installable are in fact
initialized much better.
This is possible because since we just have local variables not
fields, we can stop worrying about the not-yet-initialized case.
- Fewer lines of code! (Finally I have a large refactor that makes the
number go down not up...)
- `nix repl` is now implemented in a clearer way.
The last item deserves further mention. `nix repl` is not like the other
installable commands because instead working from once-loaded
installables, it needs to be able to load them again and again.
To properly support this, we make a new superclass
`RawInstallablesCommand`. This class has the argument parsing and
completion logic, but does *not* hand off parsed installables but
instead just the raw string arguments.
This is exactly what `nix repl` needs, and allows us to instead of
having the logic awkwardly split between `prepare`,
`useDefaultInstallables,` and `load`, have everything right next to each
other. I think this will enable future simplifications of that argument
defaulting logic, but I am saving those for a future PR --- best to keep
code motion and more complicated boolean expression rewriting separate
steps.
The "diagnostic ignored `-Woverloaded-virtual`" pragma helps because C++
doesn't like our many `run` methods. In our case, we don't mind the
shadowing it all --- it is *intentional* that the derived class only
provides a `run` method, and doesn't call any of the overridden `run`
methods.
Helps with https://github.com/NixOS/rfcs/pull/134
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It is independent of SourceExprCommand, which is about parsing
installables, except for the fact that parsing installables is one of
the many things influenced by read-only mode.
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This reverts commit 9b33ef3879a764bed4cc2404a08344c3a697a646.
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This reverts commit a75b7ba30f1e4f8b15e810fd18e63ee9552e0815, reversing
changes made to 9af16c5f742300e831a2cc400e43df1e22f87f31.
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after `nix eval --json` and `nix-instantiate --eval --json`.
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Makes `printValueAsJSON` not copy paths to the store for `nix eval
--json`, `nix-instantiate --eval --json` and `nix-env --json`.
Fixes https://github.com/NixOS/nix/issues/5612
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this slightly increases the amount of memory used for any given symbol, but this
increase is more than made up for if the symbol is referenced more than once in
the EvalState that holds it. on average every symbol should be referenced at
least twice (once to introduce a binding, once to use it), so we expect no
increase in memory on average.
symbol tables are limited to 2³² entries like position tables, and similar
arguments apply to why overflow is not likely: 2³² symbols would require as many
string instances (at 24 bytes each) and map entries (at 24 bytes or more each,
assuming that the map holds on average at most one item per bucket as the docs
say). a full symbol table would require at least 192GB of memory just for
symbols, which is well out of reach. (an ofborg eval of nixpks today creates
less than a million symbols!)
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Pos objects are somewhat wasteful as they duplicate the origin file name and
input type for each object. on files that produce more than one Pos when parsed
this a sizeable waste of memory (one pointer per Pos). the same goes for
ptr<Pos> on 64 bit machines: parsing enough source to require 8 bytes to locate
a position would need at least 8GB of input and 64GB of expression memory. it's
not likely that we'll hit that any time soon, so we can use a uint32_t index to
locate positions instead.
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we'll retain the old coerceToString interface that returns a string, but callers
that don't need the returned value to outlive the Value it came from can save
copies by using the new interface instead. for values that weren't stringy we'll
pass a new buffer argument that'll be used for storage and shouldn't be
inspected.
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- Make passing the position to `forceValue` mandatory,
this way we remember people that the position is
important for better error messages
- Add pos to all `forceValue` calls
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Given flake:
```nix
{ description = "nix json error provenance";
inputs = {};
outputs = { self }: {
jsonFunction = _: "function";
json = builtins.toJSON (_: "function");
};
}
```
- Before:
```console
❯ nix eval --json .#jsonFunction
error: cannot convert a function to JSON
```
- After:
```console
❯ nix eval --json .#jsonFunction
error: cannot convert a function to JSON
at /nix/store/b7imf1c2j4jnkg3ys7fsfbj02s5j0i4f-source/testflake/flake.nix:4:5:
3| outputs = { self }: {
4| jsonFunction = _: "function";
| ^
5| json = builtins.toJSON (_: "function");
```
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This is useful for generating the nix manpages, but it may have other
applications (like generating configuration files without a Nix store).
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This was useful for an experiment with building Nix as a single
compilation unit. It's not very useful otherwise but also doesn't
hurt...
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Better to get creative than just sprinkle arbitrary underscores.
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musl doesn't like this identifier
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(cherry picked from commit 8f41847394524fcac40d3b5620139ca7e94a18e3)
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E.g.
$ nix edit .#nixosConfigurations.bla
now works.
(cherry picked from commit d2032edb2f86e955a8a7724a27c0c3225f386500)
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E.g.
$ nix edit .#nixosConfigurations.bla
now works.
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(cherry picked from commit a0de58f471c9087d8e6cc60a6078f9940a125b15)
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This replaces the '(...)' installable syntax, which is not very
discoverable. The downside is that you can't have multiple expressions
or mix expressions and other installables.
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Thus --json no longer produces a list.
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Thus,
$ nix eval --raw '("foo")'
foo
$ nix eval --raw nixpkgs.hello
/nix/store/1y6ckg6khrdsvll54s5spcmf3w6ka9k4-hello-2.10
$ nix eval --raw '(/etc/resolv.conf)'
/nix/store/vml92ama92i8mz013nny461mlvg8mvap-resolv.conf
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Similar to "jq -r", this prints the evaluation result (which must be a
string value) unquoted.
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