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Better type deprecation messages#97114

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infinisil merged 5 commits intoNixOS:masterfrom
infinisil:type-deprecation
Sep 7, 2020
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Better type deprecation messages#97114
infinisil merged 5 commits intoNixOS:masterfrom
infinisil:type-deprecation

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@infinisil infinisil commented Sep 4, 2020 •
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Motivation for this change

We want to deprecate option types over time, but how it's currently done, it's very hard to figure out which options actually use these deprecated types. This PR improves on this by allowing types to set a deprecationMessage, which when set, is displayed along the option that uses the type.

So with an option using types.loaOf, you now get

trace: warning: The type `types.loaOf' of option `foo.bar' defined in
  `/home/infinisil/src/nixpkgs/config.nix' is deprecated. Mixing lists with
  attribute values is no longer possible; please use `types.attrsOf` instead. See
  https://github.com/NixOS/nixpkgs/issues/1800 for the motivation.

Similar for types.string and types.optionSet. I also removed types.list completely because it's been deprecated for 7 years.

Previous PR's/commits that deprecated option types: fd803fc, #54637, #66346 (#16750), #96042 (#1800, #63103, #77189)

I also plan to deprecate more types in the future.

Ping @roberth @rycee @Profpatsch @danbst @rnhmjoj @worldofpeace @cole-h

Things done
  • Checked that all the deprecated types are usable and display the deprecation message

@infinisil infinisil added the 6.topic: module system About "NixOS" module system internals label Sep 4, 2020
@ofborg ofborg bot added 10.rebuild-darwin: 0 This PR does not cause any packages to rebuild on Darwin. 10.rebuild-linux: 0 This PR does not cause any packages to rebuild on Linux. labels Sep 4, 2020
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rnhmjoj commented Sep 4, 2020

👍 for removing list: it's been deprecated since I started using NixOS and only causes confusion.

I'm not sure about the message: loaOf and list have been completely removed can still be used string can still be used.

@infinisil infinisil mentioned this pull request Sep 4, 2020
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infinisil commented Sep 4, 2020

I'm not sure about the message: loaOf and list have been completely removed can still be used string can still be used.

Not sure what you mean. loaOf is still there, it's just deprecated and aliased to attrsOf. string is also still there, it's also just deprecated and aliased to separatedString " ". Once they have been deprecated long enough we can remove them.

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rnhmjoj commented Sep 4, 2020

@infinisil I meant that the implementation of loaOf and list has been replaced with a change of semantics, while string continues to work exactly the same, except for the warning.

It was actually cole-h that noticed this in #96042

Even though types.loaOf is aliased to types.attrsOf now, I still think this counts as being removed

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infinisil commented Sep 4, 2020 •
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@rnhmjoj I guess that's just because only a subset of loaOf's functionality has been deprecated (the part about lists), while string has been deprecated because it has such a tempting name when it often isn't the right type. I don't think there's a problem with this.

@infinisil
lib/types: Allow types to emit a deprecation warning
1d46562 
Previously the only way to deprecate a type was using

  theType = lib.warn "deprecated" (mkOptionType ...)

This caused the warning to be emitted when the type was evaluated, but
the error didn't include which option actually used that type.

With this commit, types can specify a deprecationMessage, which when
non-null, is printed along with the option that uses the type
@infinisil
lib/types: Remove types.list, it's been deprecated long enough
14095f8 
Has been deprecated since fd803fc
(2013-08-22)
@infinisil
lib/types: Set deprecationMessage for types.string
2bed3b2
@infinisil
lib/types: Set deprecationMessage for types.loaOf
3b7aca4
@infinisil
lib/types: Set deprecationMessage for types.optionSet
a582f6a
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infinisil commented Sep 7, 2020

I updated it to also print the files where the option is defined.

@infinisil infinisil merged commit ed5a07c into NixOS:master Sep 7, 2020
@infinisil infinisil deleted the type-deprecation branch September 7, 2020 17:33
This was referenced Sep 27, 2020
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@roberth roberth roberth approved these changes

@edolstra edolstra Awaiting requested review from edolstra

@nbp nbp Awaiting requested review from nbp

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