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[WIP] Scala 3 #3

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[WIP] Scala 3 #3

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KuceraMartin
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@KuceraMartin KuceraMartin commented Jan 7, 2024 •
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todo:

  • fix construct0 implementation
  • implement deconstruct0
  • make all tests compile
  • support for nested classes
  • code cleanup

closes #2

@KuceraMartin KuceraMartin mentioned this pull request Jan 19, 2024
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@haskiindahouse
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Hi! Are you still working on it?

@KuceraMartin
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KuceraMartin commented Apr 25, 2024 •
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Hi! Unfortunately I encountered a problem with the Scala compiler and didn't figure out a way to get around it (see scala/scala3#19493). That's why I postponed my effort and was planning to get back to it once the compiler issue is solved.

If you want to try to do it yourself now, feel free to go for it. (and feel free to contact me if you want to discuss possible approaches)

@mrdziuban mrdziuban mentioned this pull request May 23, 2024
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lihaoyi pushed a commit that referenced this pull request May 25, 2024
@mrdziuban
Scala 3 support (#11)
7cbc5cc 
Closes #2 

## Macros

Just like @KuceraMartin in #3, I ran into scala/scala3#19493 and
scala/scala3#19436 when trying to resolve a `TypeMapper` by importing
from a `DialectTypeMappers`. As a workaround, I introduced [additional
`implicit def`s in the `TableMapper` companion
object](https://github.com/com-lihaoyi/scalasql/blob/a7d6c531bf7b9cc2f5e2c175906d2a1e961de206/scalasql/core/src/TypeMapper.scala#L58-L121)
that instead rely on an implicit instance of `DialectTypeMappers`, i.e.
in a macro:

```scala
// bad, causes a compiler crash
// TableMacro.scala
(dialect: DialectTypeMappers) => {
  import dialect.*
  summonInline[TypeMapper[t]]
}

// good
// TypeMapper.scala
implicit def stringFromDialectTypeMappers(implicit d: DialectTypeMappers): TypeMapper[String] = d.StringType

// TableMacro.scala
(dialect: DialectTypeMappers) => {
  given d: DialectTypeMappers = dialect
  summonInline[TypeMapper[t]]
}
```

## Supporting changes

In addition to building out the macros in Scala 3, the following changes
were necessary:

1. Update the generated code to ensure `def`s aren't too far to the left
-- this is to silence Scala 3 warnings
2. Convert `CharSequence`s to `String`s explicitly -- see the [error the
Scala 3 compiler reported
here](9ffeb06)
3. Remove `try` block without a corresponding `catch` -- see the
[warning the Scala 3 compiler reported
here](011c3f6)
4. Add types to implicit definitions
5. Mark `renderSql` as `private[scalasql]` instead of `protected` -- see
the [error the Scala 3 compiler reported
here](8e767e3)
6. Use Scala 3.4 -- this is a little unfortunate since it's not the LTS
but it's necessary for the Scala 3 macros to [match on higher kinded
types like
this](https://github.com/com-lihaoyi/scalasql/blob/a7d6c531bf7b9cc2f5e2c175906d2a1e961de206/scalasql/query/src-3/TableMacro.scala#L48-L52).
This type of match doesn't work in Scala 3.3
7. Replace `_` wildcards with `?` -- this is to silence Scala 3 warnings
8. Replace `Foo with Bar` in types with `Foo & Bar` -- this is to
silence Scala 3 warnings
9. Add the `-Xsource:3` compiler option for Scala 2 -- this is necessary
to use the language features mentioned in points 7 and 8
10. Add a number of type annotations to method overrides -- this is to
silence warnings reported by the Scala 2 compiler as a result of
enabling `-Xsource:3`. All of the warnings relate to the inferred type
of the method changing between Scala 2 and 3
@lihaoyi
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lihaoyi commented May 27, 2024

Superseded by #11

@lihaoyi lihaoyi closed this May 27, 2024
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Scala 3 Support (1000USD Bounty)
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@KuceraMartin @haskiindahouse @lihaoyi