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#include "experimental-features.hh"
#include "util.hh"
#include "nlohmann/json.hpp"
namespace nix {
struct ExperimentalFeatureDetails
{
ExperimentalFeature tag;
std::string_view name;
std::string_view description;
};
constexpr std::array<ExperimentalFeatureDetails, 11> xpFeatureDetails = {{
{
.tag = Xp::CaDerivations,
.name = "ca-derivations",
.description = R"(
Allows derivations to be content-addressed in order to prevent rebuilds
when changes to the derivation do not result in changes to the
derivation's output. See
[__contentAddressed](../language/advanced-attributes.md#adv-attr-__contentAddressed)
for more info.
)",
},
{
.tag = Xp::ImpureDerivations,
.name = "impure-derivations",
.description = R"(
Allows derivations to produce non-fixed outputs by setting the `__impure`
derivation attribute to `true`. See [these release
notes](../release-notes/rl-2.8.md) for an example.
)",
},
{
.tag = Xp::Flakes,
.name = "flakes",
.description = R"(
Allows for derivations to be packaged in flakes. See the manual entry for
[`nix flake`](../command-ref/new-cli/nix3-flake.md) or this [detailed
introduction](https://www.tweag.io/blog/2020-05-25-flakes/) for more info.
)",
},
{
.tag = Xp::NixCommand,
.name = "nix-command",
.description = R"(
Allows the usage of the new `nix` CLI subcommands, such as `nix build`, `nix
develop`, `nix run`, etc. See the manual for
[`nix`](../command-ref/new-cli/nix.md) for more info.
)",
},
{
.tag = Xp::RecursiveNix,
.name = "recursive-nix",
.description = R"(
Allow Nix derivations to call Nix in order to recursively build derivations.
See [this
commit](https://github.com/edolstra/nix/commit/1a27aa7d64ffe6fc36cfca4d82bdf51c4d8cf717)
for more info.
)",
},
{
.tag = Xp::NoUrlLiterals,
.name = "no-url-literals",
.description = R"(
Disallows unquoted URLs as part of the Nix language syntax. See [RFC
45](https://github.com/NixOS/rfcs/pull/45) for more info.
)",
},
{
.tag = Xp::FetchClosure,
.name = "fetch-closure",
.description = R"(
Enables the use of the `fetchClosure` function in the standard library. See
the docs for [`fetchClosure`](../language/builtins.md#builtins-fetchClosure)
for more info.
)",
},
{
.tag = Xp::ReplFlake,
.name = "repl-flake",
.description = R"(
Allows the user to enter a Nix REPL within a flake, e.g. `nix repl nixpkgs`
or `nix repl .#foo`.
)",
},
{
.tag = Xp::AutoAllocateUids,
.name = "auto-allocate-uids",
.description = R"(
Allows Nix to automatically pick UIDs for builds, rather than creating
`nixbld*` user accounts. See [here](#conf-auto-allocate-uids) for more info.
)",
},
{
.tag = Xp::Cgroups,
.name = "cgroups",
.description = R"(
Allows Nix to execute builds inside cgroups. See
[`use-cgroups`](#conf-use-cgroups) for more info.
)",
},
{
.tag = Xp::DiscardReferences,
.name = "discard-references",
.description = R"(
Enables the use of the `unsafeDiscardReferences` attribute in derivations
that use structured attributes. This disables scanning of outputs for
runtime dependencies.
)",
},
}};
static_assert(
[]() constexpr {
for (auto [index, feature] : enumerate(xpFeatureDetails))
if (index != (size_t)feature.tag)
return false;
return true;
}(),
"array order does not match enum tag order");
const std::optional<ExperimentalFeature> parseExperimentalFeature(const std::string_view & name)
{
using ReverseXpMap = std::map<std::string_view, ExperimentalFeature>;
static std::unique_ptr<ReverseXpMap> reverseXpMap = [](){
auto reverseXpMap = std::make_unique<ReverseXpMap>();
for (auto & xpFeature : xpFeatureDetails)
(*reverseXpMap)[xpFeature.name] = xpFeature.tag;
return reverseXpMap;
}();
if (auto feature = get(*reverseXpMap, name))
return *feature;
else
return std::nullopt;
}
std::string_view showExperimentalFeature(const ExperimentalFeature tag)
{
assert((size_t)tag < xpFeatureDetails.size());
return xpFeatureDetails[(size_t)tag].name;
}
std::string getExperimentalFeaturesList() {
std::string experimentalFeaturesList = R"(
Experimental Nix features to enable.
Current experimental features are the following:
)";
for (auto & xpFeature : xpFeatureDetails) {
experimentalFeaturesList += std::string {}
/* length of this first string must be 12, matching the indent of
the descriptions in the xpFeatureDetails literal. FIXME compute
markdown in a less hacky way. */
+ " - "
+ "`" + xpFeature.name + "`"
+ "\n"
+ xpFeature.description
+ "\n\n";
}
return experimentalFeaturesList;
}
std::set<ExperimentalFeature> parseFeatures(const std::set<std::string> & rawFeatures)
{
std::set<ExperimentalFeature> res;
for (auto & rawFeature : rawFeatures)
if (auto feature = parseExperimentalFeature(rawFeature))
res.insert(*feature);
return res;
}
MissingExperimentalFeature::MissingExperimentalFeature(ExperimentalFeature feature)
: Error("experimental Nix feature '%1%' is disabled; use '--extra-experimental-features %1%' to override", showExperimentalFeature(feature))
, missingFeature(feature)
{}
std::ostream & operator <<(std::ostream & str, const ExperimentalFeature & feature)
{
return str << showExperimentalFeature(feature);
}
void to_json(nlohmann::json & j, const ExperimentalFeature & feature)
{
j = showExperimentalFeature(feature);
}
void from_json(const nlohmann::json & j, ExperimentalFeature & feature)
{
const std::string input = j;
const auto parsed = parseExperimentalFeature(input);
if (parsed.has_value())
feature = *parsed;
else
throw Error("Unknown experimental feature '%s' in JSON input", input);
}
}
|
