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Detect quoted pattern variables in alternatives #15073

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merged 2 commits into from
May 9, 2022
Merged

Detect quoted pattern variables in alternatives #15073

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9ed7ac5
Detect quoted pattern variables in alternatives
nicolasstucki Apr 29, 2022
b61181f
Do not remove InPatternAlternative when typing subexpressions
nicolasstucki May 5, 2022
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19 changes: 17 additions & 2 deletions compiler/src/dotty/tools/dotc/typer/QuotesAndSplices.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ import dotty.tools.dotc.typer.Implicits._
import dotty.tools.dotc.typer.Inferencing._
import dotty.tools.dotc.util.Spans._
import dotty.tools.dotc.util.Stats.record

import dotty.tools.dotc.reporting.IllegalVariableInPatternAlternative
import scala.collection.mutable


Expand Down Expand Up @@ -243,6 +243,17 @@ trait QuotesAndSplices {
res
}

def checkAlternativeBinds(pat0: Tree): Unit =
def rec(pat: Tree): Unit =
pat match
case Typed(pat, _) => rec(pat)
case UnApply(_, _, pats) => pats.foreach(rec)
case pat: Bind =>
report.error(IllegalVariableInPatternAlternative(pat.symbol.name), pat.withSpan(pat.nameSpan))
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How come we need to check this here, isn't typedBind going to run on this tree later and produce the same error via https://github.com/lampepfl/dotty/blob/400427db21410b366e4d9b890d73cec15416b632/compiler/src/dotty/tools/dotc/typer/Typer.scala#L2141-L2142 ?

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The context at that point lost the mode InPatternAlternative. Now I found out where that is happening and will push a better fix.

rec(pat.body)
case _ =>
if ctx.mode.is(Mode.InPatternAlternative) then rec(pat0)

val patBuf = new mutable.ListBuffer[Tree]
val freshTypePatBuf = new mutable.ListBuffer[Tree]
val freshTypeBindingsBuff = new mutable.ListBuffer[Tree]
Expand All @@ -254,6 +265,7 @@ trait QuotesAndSplices {
val newSplice = ref(defn.QuotedRuntime_exprSplice).appliedToType(tpt1.tpe).appliedTo(Typed(pat, exprTpt))
transform(newSplice)
case Apply(TypeApply(fn, targs), Apply(sp, pat :: Nil) :: args :: Nil) if fn.symbol == defn.QuotedRuntimePatterns_patternHigherOrderHole =>
checkAlternativeBinds(pat)
args match // TODO support these patterns. Possibly using scala.quoted.util.Var
case SeqLiteral(args, _) =>
for arg <- args; if arg.symbol.is(Mutable) do
Expand All @@ -266,6 +278,7 @@ trait QuotesAndSplices {
patBuf += pat1
}
case Apply(fn, pat :: Nil) if fn.symbol.isExprSplice =>
checkAlternativeBinds(pat)
try ref(defn.QuotedRuntimePatterns_patternHole.termRef).appliedToType(tree.tpe).withSpan(tree.span)
finally {
val patType = pat.tpe.widen
Expand Down Expand Up @@ -321,7 +334,9 @@ trait QuotesAndSplices {
}

private def transformTypeBindingTypeDef(nameOfSyntheticGiven: TermName, tdef: TypeDef, buff: mutable.Builder[Tree, List[Tree]])(using Context): Tree = {
if (variance == -1)
if ctx.mode.is(Mode.InPatternAlternative) then
report.error(IllegalVariableInPatternAlternative(tdef.symbol.name), tdef.srcPos)
if variance == -1 then
tdef.symbol.addAnnotation(Annotation(New(ref(defn.QuotedRuntimePatterns_fromAboveAnnot.typeRef)).withSpan(tdef.span)))
val bindingType = getBinding(tdef.symbol).symbol.typeRef
val bindingTypeTpe = AppliedType(defn.QuotedTypeClass.typeRef, bindingType :: Nil)
Expand Down
27 changes: 27 additions & 0 deletions tests/neg-macros/i14696.scala
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@@ -0,0 +1,27 @@
import scala.quoted.*

def test(a: Expr[Any])(using Quotes): Unit = a match
case '{ ${_}: String } | '{ ${_}: Int } =>
case '{ $x1: String } | '{ ${_}: Int } => // error
case '{ $x: String } | '{ $x: Int } => // error // error
case '{ $x1: String } | '{ ${x2: Expr[Int]} } => // error // error
case '{ ${Str(x)}: String } | '{ ${y @ Str(z)}: Int } => // error // error // error
case '{ val x: Int = ???; ${_}(x): String } | '{ '{ val x: String = ???; ${_}(x): String }} =>
case '{ val x: Int = ???; $f(x): String } | '{ val x: String = ???; ${_}(x): String } => // error
case '{ val x: Int = ???; $f(x): String } | '{ val x: String = ???; $f(x): String } => // error // error
case '{ val x: Int = ???; $f(x): String } | '{ val x: String = ???; $g(x): String } => // error // error
case '{ varargs(${_}*) } | '{ varargs(${_}*) } =>
case '{ varargs($args*) } | '{ varargs(${_}*) } => // error
case '{ varargs($args*) } | '{ varargs($args*) } => // error // error
case '{ varargs($args1*) } | '{ varargs($args2*) } => // error // error
case '{ ${_}: t } | '{ ${_}: Int } => // error
case '{ ${_}: t } | '{ ${_}: t } => // error // error
case '{ ${_}: t } | '{ ${_}: u } => // error // error
case '{ type t; () } | '{ 1 } => // error
case '{ type t; () } | '{ type t; () } => // error // error
case '{ type t; () } | '{ type u; () } => // error // error

def varargs(x: Any*): Unit = ()

object Str:
def unapply(x: Any): Option[String] = ???