Add experimental-features setting

Experimental features are now opt-in. There is currently one
experimental feature: "nix-command" (which enables the "nix"
command. This will allow us to merge experimental features more
quickly, without committing to supporting them indefinitely.

Typical usage:

$ nix build --experimental-features 'nix-command flakes' nixpkgs#hello

(cherry picked from commit 8e478c2341,
without the "flakes" feature)
This commit is contained in:
Eelco Dolstra 2019-10-16 17:45:09 +02:00
parent 389a2cebed
commit aabf5c86c9
No known key found for this signature in database
GPG key ID: 8170B4726D7198DE
4 changed files with 15 additions and 0 deletions

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@ -105,6 +105,13 @@ StringSet Settings::getDefaultSystemFeatures()
return features; return features;
} }
void Settings::requireExperimentalFeature(const std::string & name)
{
auto & f = experimentalFeatures.get();
if (std::find(f.begin(), f.end(), name) == f.end())
throw Error("experimental Nix feature '%s' is disabled", name);
}
const string nixVersion = PACKAGE_VERSION; const string nixVersion = PACKAGE_VERSION;
template<> void BaseSetting<SandboxMode>::set(const std::string & str) template<> void BaseSetting<SandboxMode>::set(const std::string & str)

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@ -353,6 +353,11 @@ public:
Setting<Paths> pluginFiles{this, {}, "plugin-files", Setting<Paths> pluginFiles{this, {}, "plugin-files",
"Plugins to dynamically load at nix initialization time."}; "Plugins to dynamically load at nix initialization time."};
Setting<Strings> experimentalFeatures{this, {}, "experimental-features",
"Experimental Nix features to enable."};
void requireExperimentalFeature(const std::string & name);
}; };

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@ -138,6 +138,8 @@ void mainWrapped(int argc, char * * argv)
args.parseCmdline(argvToStrings(argc, argv)); args.parseCmdline(argvToStrings(argc, argv));
settings.requireExperimentalFeature("nix-command");
initPlugins(); initPlugins();
if (!args.command) args.showHelpAndExit(); if (!args.command) args.showHelpAndExit();

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@ -17,6 +17,7 @@ cat > "$NIX_CONF_DIR"/nix.conf <<EOF
build-users-group = build-users-group =
keep-derivations = false keep-derivations = false
sandbox = false sandbox = false
experimental-features = nix-command
include nix.conf.extra include nix.conf.extra
EOF EOF