Make into a preview feature
#24090
Make into a preview feature
#24090
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| * `T`. Hence, we don't need to use `.underlying` to go from an into type to its | ||
| * underlying type in the types of local parameters. | ||
| */ | ||
| @experimental |
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Shouldn't it now use @scala.annotation.internal.preview annotation instead of making it stable?
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This is not really needed. It is an internal annotation that people will not use manually.
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Well, even then. In theory it's part of a preview feature, and could be altered. (Very very unlikely in this case, but let's follow the procedure, so that the next person who comes to this PR in search for a reference of how a feature becomes preview doesn't get misled.)
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I agree, if we were to be pedantic, we should put it. I just claimed that from an implementation point of view, it is not really needed.
| * @see [[https://dotty.epfl.ch/docs/reference/experimental/into-modifier]] | ||
| */ | ||
| @compileTimeOnly("`into` can only be used at compile time in import statements") | ||
| @deprecated("The into language import is no longer needed since the feature is now standard", since = "3.9") |
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Not sure about this one, and how it should be handled. From the perspective of user it would be better to now get hint about preview, and standard when it's actually standardised in 3.9 or later
| @deprecated("The into language import is no longer needed since the feature is now standard", since = "3.9") | |
| @deprecated("The into language import is no longer needed since the feature is now in preview", since = "3.9") |
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perhaps hint about preview since 3.8...
and standard whenever we stabilise
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We should not say since 3.9.0 in 3.8.0. It makes no sense. I think we should say (preview, 3.8.0) and change it to (stable, 3.9.0) later or say directly (stable, 3.8.0).
tgodzik
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needs-minor-release
| * `T`. Hence, we don't need to use `.underlying` to go from an into type to its | ||
| * underlying type in the types of local parameters. | ||
| */ | ||
| @experimental |
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This is not really needed. It is an internal annotation that people will not use manually.
| * @see [[https://dotty.epfl.ch/docs/reference/experimental/into-modifier]] | ||
| */ | ||
| @compileTimeOnly("`into` can only be used at compile time in import statements") | ||
| @deprecated("The into language import is no longer needed since the feature is now standard", since = "3.9") |
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| @deprecated("The into language import is no longer needed since the feature is now standard", since = "3.9") | |
| @deprecated("The into language import is no longer needed since the feature is now standard", since = "3.8.0") |
library/src/scala/language.scala
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| * @see [[https://dotty.epfl.ch/docs/reference/experimental/into-modifier]] | ||
| */ | ||
| @compileTimeOnly("`into` can only be used at compile time in import statements") | ||
| @deprecated("The into language import is no longer needed since the feature is now standard", since = "3.9") |
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| @deprecated("The into language import is no longer needed since the feature is now standard", since = "3.9") | |
| @deprecated("The into language import is no longer needed since the feature is now standard", since = "3.8.0") |
| TRACKED | ||
| INTO -- a tracked class parameter / a dependent class |
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| TRACKED | |
| INTO -- a tracked class parameter / a dependent class | |
| TRACKED -- a tracked class parameter / a dependent class | |
| INTO |
| * conversions are tried from the type of `t` to `T`. `into[T]` types are erased to `T` | ||
| * in all covariant positions of the types of parameter symbols. | ||
| */ | ||
| @experimental |
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This one is important, if we don't mark this alias with @preview, we will not be able to enforce it.
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| /** Unwrap an `into` */ | ||
| extension [T](x: into[T]) | ||
| @experimental def underlying: T = x |
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This one should also be marked as @preview, otherwise we will be compiling the library with -preview
- Make all aspects of into a -preview feature - Drop experimental import in tests
Since SIP 71 is now accepted, we can ship it as -preview in 3.8 and standard in 3.9.
Note to tooling implementers
There are two relevant pieces that need to be implemented in IDEs:
intois a new soft modifier for classes, traits, and enums. Types withintoare legal conversion target types. SeeisConversionTargetTypeinTypes.scala.Conversion.intotype is a regular opaque type, so should not need any support by itself. However, there's a rule that no-flip covariant occurrences ofinto[T]in method parameters are mapped toT @$into, where$intois an annotation inannotation.internal. The annotation is "silent" which means it should not be shown in inferred types. The purpose of that mapping is thatinto[...]does not have to be explicitly stripped in method bodies. SeesuppressIntoandrevealIntoin TypeOps./cc @unkarjedy @tgodzik