Warn when experimental features are used #3744
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If you use an experimental feature not listed in the 'experimental-features' setting, you now get a warning rather than a fatal error. This makes things like the 'nix' command a bit less obnoxious. However, if you set 'allow-experimental-features = false', it's still a fatal error. This is primarily for CI systems where use of experimental features in the daemon could go unnoticed.
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I don't think all experimental features should be enabled automatically. Maybe we should include |
| throw Error("experimental Nix feature '%1%' is disabled; use '--experimental-features %1%' to override", name); | ||
| if (!isExperimentalFeatureEnabled(name)) { | ||
| if (allowExperimentalFeatures) { | ||
| static Sync<std::unordered_set<std::string>> warned; |
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this requires #include <unordered_set> for PRECOMPILE_HEADERS=0
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Are there other experimental features now besides Is " |
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Let's keep this unchanged for now. |
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Yes, I can imagine people complaining "but the warning was burried in a huge log, and I had no idea I was using an unstable feature". Thanks for not doing this! |
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On the other hand, maintaining tutorials of any kind is going to be really painful, because now Nix 2.3 rejects |
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We could backport the experimental-features flag to 2.3. |
If you use an experimental feature not listed in the
experimental-featuressetting, you now get a warning rather than a fatal error. This makes things like the 'nix' command a bit less obnoxious.However, if you set
allow-experimental-features = false, it's still a fatal error. This is primarily for CI systems where use of experimental features in the daemon could go unnoticed.