Stabilise Quotes reflect methods used for creating new classes/objects (#23826)

This PR stabilizes Quotes reflect methods:
* 3 overloaded versions of `Symbol.newClass` - the first one added in
3.3.0, updated in 3.7.0. Basically necessary for mock tests, and already
used in `ScalaMock` via workarounds - so somewhat battle tested.
* `ClassDef.apply` - added in 3.3.0, used in conjunction with
`Symbol.newClass`.
* The `Symbol.newModule` - added in 3.3.0, updated in 3.7.0. Not as
widely used, but generally similar to the above. If we ever need more
features there, we can add those via overloading.
* `ClassDef.module` - added in 3.3.0, used in conjunction with
`Symbol.newModule`.
* `Symbol.freshName` - added in 3.3.0. Not strictly necessary, but
useful even without Macro Annotations. The design is simple enough (and
API identical to scala-2 counterpart), where I don't see anything that
could go wrong here. Already used in some project via a workaround
(Chimney).

The main idea here is to be finally able to use mocking libraries
without any ugly workarounds or `--experimental` options. With that
said, there are more methods in Quotes reflect that have been
experimental for some time now:
* `Symbol.newTypeBounds`, `Symbol.newTypeAlias` - added in 3.6.0. I
believe they could be stabilized, and I planned to add them in this PR,
but found some leftover todos (connected to the implementation, not the
API) so I'll fix those and submit separately.
* `Symbol.info` - added in 3.3.0. To be honest, I'd prefer if this was
removed. Naturally `info` can return a `ClassInfo` which we currently do
not support in the reflection API (so this can cause crashes currently).
We would also need an `asSeenFrom` method added for this to be useful.
We already have a method to return types of Symbols, with
`Symbol.typeMember`, which already can return complete type information,
making info + asSeenFrom redundant. Currently, in tests, it is used to
more easily copy type information of one Symbol, when creating another
(like when overwriting a `hashCode` method). There must be a better way
to do that than accessing the raw `info` of any Symbol (perhaps we could
add a `methodInfo` instead, which would, by design, not work for
Classes)
* `GivenSelectorModule.apply`, `OmitSelectorModule.apply`,
`RenameSelectorModule.apply`, `SimpleSelectorModule.apply`- Added in
3.7.0. I'd prefer if we waited with these a bit. Added by an outside
contributor, I tried to look for solid arguments not to add them,
couldn't really find any, merged them and I got some pushback after
doing so from other contributors. Ideally, when unused-imports become
more stable/complete, we'll be able to better see the impact of those
methods.
* other ones like `erasedParams` and `erasedArgs` are still connected to
other experimental features, so they should be left as-is.

Author: hamzaremmal

library/src/scala/quoted/Quotes.scala

@@ -493,7 +493,8 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
        *  @param body List of members of the class. The members must align with the members of `cls`.
        */
       // TODO add selfOpt: Option[ValDef]?
-      @experimental def apply(cls: Symbol, parents: List[Tree /* Term | TypeTree */], body: List[Statement]): ClassDef
+      // ^ if a use-case shows up, we add this via an overloaded method
+      def apply(cls: Symbol, parents: List[Tree /* Term | TypeTree */], body: List[Statement]): ClassDef
       def copy(original: Tree)(name: String, constr: DefDef, parents: List[Tree /* Term | TypeTree */], selfOpt: Option[ValDef], body: List[Statement]): ClassDef
       def unapply(cdef: ClassDef): (String, DefDef, List[Tree /* Term | TypeTree */], Option[ValDef], List[Statement])
 
@@ -518,7 +519,8 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
        *  @syntax markdown
        */
       // TODO add selfOpt: Option[ValDef]?
-      @experimental def module(module: Symbol, parents: List[Tree /* Term | TypeTree */], body: List[Statement]): (ValDef, ClassDef)
+      // ^ if a use-case shows up, we can add this via an overloaded method
+      def module(module: Symbol, parents: List[Tree /* Term | TypeTree */], body: List[Statement]): (ValDef, ClassDef)
     }
 
     /** Makes extension methods on `ClassDef` available without any imports */
@@ -3878,7 +3880,7 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
        *  @note As a macro can only splice code into the point at which it is expanded, all generated symbols must be
        *        direct or indirect children of the reflection context's owner.
        */
-      @experimental def newClass(owner: Symbol, name: String, parents: List[TypeRepr], decls: Symbol => List[Symbol], selfType: Option[TypeRepr]): Symbol
+       def newClass(owner: Symbol, name: String, parents: List[TypeRepr], decls: Symbol => List[Symbol], selfType: Option[TypeRepr]): Symbol
 
       /** Generates a new class symbol for a class with a public single term clause constructor.
        *
@@ -3936,7 +3938,7 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
        *  @note As a macro can only splice code into the point at which it is expanded, all generated symbols must be
        *        direct or indirect children of the reflection context's owner.
        */
-      @experimental def newClass(
+      def newClass(
         owner: Symbol,
         name: String,
         parents: Symbol => List[TypeRepr],
@@ -4038,7 +4040,7 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
        */
       // Keep doc aligned with QuotesImpl's validFlags: `clsFlags` with `validClassFlags`, `conFlags` with `validClassConstructorFlags`,
       // conParamFlags with `validClassTypeParamFlags` and `validClassTermParamFlags`
-      @experimental def newClass(
+      def newClass(
         owner: Symbol,
         name: String,
         parents: Symbol => List[TypeRepr],
@@ -4110,7 +4112,7 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
        *
        *  @syntax markdown
        */
-      @experimental def newModule(owner: Symbol, name: String, modFlags: Flags, clsFlags: Flags, parents: Symbol => List[TypeRepr], decls: Symbol => List[Symbol], privateWithin: Symbol): Symbol
+      def newModule(owner: Symbol, name: String, modFlags: Flags, clsFlags: Flags, parents: Symbol => List[TypeRepr], decls: Symbol => List[Symbol], privateWithin: Symbol): Symbol
 
       /** Generates a new method symbol with the given parent, name and type.
        *
@@ -4225,7 +4227,6 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
        *
        *  @param prefix Prefix of the fresh name
        */
-      @experimental
       def freshName(prefix: String): String
     }
 

project/MiMaFilters.scala

@@ -138,6 +138,9 @@ object MiMaFilters {
           ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#MethodTypeMethods.isContextual"),
           ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#ImplicitsModule.searchIgnoring"),
           ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#ValDefModule.let"),
+          ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#SymbolModule.newClass"),
+          ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#SymbolModule.newModule"),
+
           // Change `experimental` annotation to a final class
           ProblemFilters.exclude[FinalClassProblem]("scala.annotation.experimental"),
 

tests/neg-macros/i19842-a.check

@@ -11,7 +11,7 @@
   |	at dotty.tools.dotc.transform.TreeChecker$.checkParents(TreeChecker.scala:210)
   |	at scala.quoted.runtime.impl.QuotesImpl$reflect$ClassDef$.module(QuotesImpl.scala:286)
   |	at scala.quoted.runtime.impl.QuotesImpl$reflect$ClassDef$.module(QuotesImpl.scala:285)
-  |	at Macros$.makeSerializer(Macro.scala:25)
+  |	at Macros$.makeSerializer(Macro.scala:23)
   |
   |---------------------------------------------------------------------------------------------------------------------
   |Inline stack trace

tests/neg-macros/i19842-a/Macro.scala

@@ -1,5 +1,3 @@
-//> using options -experimental
-
 import scala.annotation.{experimental, targetName}
 import scala.quoted.*
 import scala.util.Try

tests/neg-macros/i19842-b.check

@@ -11,7 +11,7 @@
   |	at dotty.tools.dotc.transform.TreeChecker$.checkParents(TreeChecker.scala:210)
   |	at scala.quoted.runtime.impl.QuotesImpl$reflect$ClassDef$.module(QuotesImpl.scala:286)
   |	at scala.quoted.runtime.impl.QuotesImpl$reflect$ClassDef$.module(QuotesImpl.scala:285)
-  |	at Macros$.makeSerializer(Macro.scala:27)
+  |	at Macros$.makeSerializer(Macro.scala:25)
   |
   |---------------------------------------------------------------------------------------------------------------------
   |Inline stack trace

tests/neg-macros/i19842-b/Macro.scala

@@ -1,5 +1,3 @@
-//> using options -experimental
-
 import scala.annotation.{experimental, targetName}
 import scala.quoted.*
 import scala.util.Try

tests/neg-macros/newClassExtendsNoParents/Macro_1.scala

@@ -1,5 +1,3 @@
-//> using options -experimental
-
 import scala.quoted.*
 
 inline def makeClass(inline name: String): Any = ${ makeClassExpr('name) }

tests/neg-macros/newClassExtendsNoParents/Test_2.scala

@@ -1,3 +1 @@
-//> using options -experimental
-
 def test: Any = makeClass("foo") // error

tests/neg-macros/newClassExtendsOnlyTrait/Macro_1.scala

@@ -1,5 +1,3 @@
-//> using options -experimental
-
 import scala.quoted.*
 
 inline def makeClass(inline name: String): Foo = ${ makeClassExpr('name) }

tests/neg-macros/newClassExtendsOnlyTrait/Test_2.scala

@@ -1,3 +1 @@
-//> using options -experimental
-
 def test: Foo = makeClass("foo") // error