Make explicit arguments for context bounds an error from 3.5 #19316
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| Original file line number | Diff line number | Diff line change | ||||
|---|---|---|---|---|---|---|
| @@ -0,0 +1,108 @@ | ||||||
| package dotty.tools | ||||||
| package dotc | ||||||
| package typer | ||||||
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| import core.* | ||||||
| import ast.* | ||||||
| import Contexts.* | ||||||
| import Types.* | ||||||
| import Flags.* | ||||||
| import Names.* | ||||||
| import StdNames.* | ||||||
| import Symbols.* | ||||||
| import Trees.* | ||||||
| import ProtoTypes.* | ||||||
| import Decorators.* | ||||||
| import config.MigrationVersion | ||||||
| import config.Feature.{sourceVersion, migrateTo3} | ||||||
| import config.SourceVersion.* | ||||||
| import reporting.* | ||||||
| import NameKinds.ContextBoundParamName | ||||||
| import rewrites.Rewrites.patch | ||||||
| import util.Spans.Span | ||||||
| import rewrites.Rewrites | ||||||
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| /** A utility trait containing source-dependent deprecation messages | ||||||
| * and migrations. | ||||||
| */ | ||||||
| trait Migrations: | ||||||
| this: Typer => | ||||||
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| import tpd.* | ||||||
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| /** Flag & migrate `?` used as a higher-kinded type parameter | ||||||
| * Warning in 3.0-migration, error from 3.0 | ||||||
| */ | ||||||
| def kindProjectorQMark(tree: untpd.TypeDef, sym: Symbol)(using Context): Unit = | ||||||
| if tree.name eq tpnme.? then | ||||||
| val addendum = if sym.owner.is(TypeParam) | ||||||
| then ", use `_` to denote a higher-kinded type parameter" | ||||||
| else "" | ||||||
| val namePos = tree.sourcePos.withSpan(tree.nameSpan) | ||||||
| report.errorOrMigrationWarning( | ||||||
| em"`?` is not a valid type name$addendum", namePos, MigrationVersion.Scala2to3) | ||||||
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| def typedAsFunction(tree: untpd.PostfixOp, pt: Type)(using Context): Tree = { | ||||||
| val untpd.PostfixOp(qual, Ident(nme.WILDCARD)) = tree: @unchecked | ||||||
| val pt1 = if (defn.isFunctionNType(pt)) pt else AnyFunctionProto | ||||||
| val nestedCtx = ctx.fresh.setNewTyperState() | ||||||
| val res = typed(qual, pt1)(using nestedCtx) | ||||||
| res match { | ||||||
| case closure(_, _, _) => | ||||||
| case _ => | ||||||
| val recovered = typed(qual)(using ctx.fresh.setExploreTyperState()) | ||||||
| val msg = OnlyFunctionsCanBeFollowedByUnderscore(recovered.tpe.widen, tree) | ||||||
| report.errorOrMigrationWarning(msg, tree.srcPos, MigrationVersion.Scala2to3) | ||||||
| if MigrationVersion.Scala2to3.needsPatch then | ||||||
| // Under -rewrite, patch `x _` to `(() => x)` | ||||||
| msg.actions | ||||||
| .headOption | ||||||
| .foreach(Rewrites.applyAction) | ||||||
| return typed(untpd.Function(Nil, qual), pt) | ||||||
| } | ||||||
| nestedCtx.typerState.commit() | ||||||
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| lazy val (prefix, suffix) = res match { | ||||||
| case Block(mdef @ DefDef(_, vparams :: Nil, _, _) :: Nil, _: Closure) => | ||||||
| val arity = vparams.length | ||||||
| if (arity > 0) ("", "") else ("(() => ", "())") | ||||||
| case _ => | ||||||
| ("(() => ", ")") | ||||||
| } | ||||||
| def remedy = | ||||||
| if ((prefix ++ suffix).isEmpty) "simply leave out the trailing ` _`" | ||||||
| else s"use `$prefix<function>$suffix` instead" | ||||||
| def rewrite = Message.rewriteNotice("This construct", `3.4-migration`) | ||||||
|
There was a problem hiding this comment. This should be
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| report.errorOrMigrationWarning( | ||||||
| em"""The syntax `<function> _` is no longer supported; | ||||||
| |you can $remedy$rewrite""", | ||||||
| tree.srcPos, | ||||||
| MigrationVersion.FunctionUnderscore) | ||||||
| if MigrationVersion.FunctionUnderscore.needsPatch then | ||||||
| patch(Span(tree.span.start), prefix) | ||||||
| patch(Span(qual.span.end, tree.span.end), suffix) | ||||||
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| res | ||||||
| } | ||||||
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| /** Flag & migrate explicit normal arguments to parameters coming from context bounds | ||||||
| * Warning in 3.4, error in 3.5, rewrite in 3.5-migration. | ||||||
| */ | ||||||
| def contextBoundParams(tree: Tree, tp: Type, pt: FunProto)(using Context): Unit = | ||||||
| def isContextBoundParams = tp.stripPoly match | ||||||
| case MethodType(ContextBoundParamName(_) :: _) => true | ||||||
| case _ => false | ||||||
| if sourceVersion.isAtLeast(`3.4`) | ||||||
| && isContextBoundParams | ||||||
| && pt.applyKind != ApplyKind.Using | ||||||
| then | ||||||
| def rewriteMsg = Message.rewriteNotice("This code", `3.5-migration`) | ||||||
|
There was a problem hiding this comment. This should use |
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| report.errorOrMigrationWarning( | ||||||
| em"""Context bounds will map to context parameters. | ||||||
| |A `using` clause is needed to pass explicit arguments to them.$rewriteMsg""", | ||||||
| tree.srcPos, MigrationVersion(`3.4`, `3.5`)) | ||||||
|
There was a problem hiding this comment. This migration version should be defined in |
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| if sourceVersion.isAtLeast(`3.5-migration`) then | ||||||
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There was a problem hiding this comment. This should use |
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| patch(Span(pt.args.head.span.start), "using ") | ||||||
| end contextBoundParams | ||||||
|
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| end Migrations | ||||||
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|
There was a problem hiding this comment. Tests with warnings should now be added to
class C[T]
def foo[X: C] = ()
given [T]: C[T] = C[T]()
def Test =
foo(C[Int]()) // warn
foo(using C[Int]()) // ok |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,10 @@ | ||
| //> using options -Xfatal-warnings | ||
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|
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| class C[T] | ||
| def foo[X: C] = () | ||
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|
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| given [T]: C[T] = C[T]() | ||
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| def Test = | ||
| foo(C[Int]()) // error | ||
| foo(using C[Int]()) // ok |
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I am not convinced we should make this one a mixin. The one use case right now for
typedAsFunction, all other functions that are here and could go in here seem to be static.I would suggest making
Migrationsanobjectand redefiningTyper.typedAsFunctionasThere was a problem hiding this comment.
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I think there's nothing wrong with a mixin, and the hack of passing an explicit typer is worse. Right now it only applies tp
typedAsFunctionbut I am sure that will not stay the only one.