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fix: simplify infer type for apply #23434

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Merged
merged 1 commit into from
Jun 30, 2025
Merged

fix: simplify infer type for apply #23434

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38 changes: 4 additions & 34 deletions presentation-compiler/src/main/dotty/tools/pc/InferExpectedType.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -50,12 +50,12 @@ class InferExpectedType(
val indexedCtx = IndexedContext(pos)(using locatedCtx)
val printer =
ShortenedTypePrinter(search, IncludeDefaultParam.ResolveLater)(using indexedCtx)
InterCompletionType.inferType(path)(using newctx).map{
InferCompletionType.inferType(path)(using newctx).map{
tpe => printer.tpe(tpe)
}
case None => None

object InterCompletionType:
object InferCompletionType:
def inferType(path: List[Tree])(using Context): Option[Type] =
path match
case (lit: Literal) :: Select(Literal(_), _) :: Apply(Select(Literal(_), _), List(s: Select)) :: rest if s.symbol == defn.Predef_undefined => inferType(rest, lit.span)
Expand Down Expand Up @@ -94,37 +94,7 @@ object InterCompletionType:
else Some(UnapplyArgs(fun.tpe.finalResultType, fun, pats, NoSourcePosition).argTypes(ind))
// f(@@)
case ApplyExtractor(app) =>
val argsAndParams = ApplyArgsExtractor.getArgsAndParams(None, app, span).headOption
argsAndParams.flatMap:
case (args, params) =>
val idx = args.indexWhere(_.span.contains(span))
val param =
if idx >= 0 && params.length > idx then Some(params(idx).info)
else None
param match
// def f[T](a: T): T = ???
// f[Int](@@)
// val _: Int = f(@@)
case Some(t : TypeRef) if t.symbol.is(Flags.TypeParam) =>
for
(typeParams, args) <-
app match
case Apply(TypeApply(fun, args), _) =>
val typeParams = fun.symbol.paramSymss.headOption.filter(_.forall(_.isTypeParam))
typeParams.map((_, args.map(_.tpe)))
// val f: (j: "a") => Int
// f(@@)
case Apply(Select(v, StdNames.nme.apply), _) =>
v.symbol.info match
case AppliedType(des, args) =>
Some((des.typeSymbol.typeParams, args))
case _ => None
case _ => None
ind = typeParams.indexOf(t.symbol)
tpe <- args.get(ind)
if !tpe.isErroneous
yield tpe
case Some(tpe) => Some(tpe)
case _ => None
val idx = app.args.indexWhere(_.span.contains(span))
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Och wow, that is much simpler!

app.fun.tpe.widenTermRefExpr.paramInfoss.flatten.get(idx)
case _ => None

2 changes: 1 addition & 1 deletion presentation-compiler/src/main/dotty/tools/pc/completions/Completions.scala
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Expand Up @@ -520,7 +520,7 @@ class Completions(
config.isCompletionSnippetsEnabled()
)
(args, false)
val singletonCompletions = InterCompletionType.inferType(path).map(
val singletonCompletions = InferCompletionType.inferType(path).map(
SingletonCompletions.contribute(path, _, completionPos)
).getOrElse(Nil)
(singletonCompletions ++ advanced, exclusive)
Expand Down
75 changes: 75 additions & 0 deletions presentation-compiler/test/dotty/tools/pc/tests/InferExpectedTypeSuite.scala
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Expand Up @@ -47,6 +47,24 @@ class InferExpectedTypeSuite extends BasePCSuite:
|""".stripMargin
)

@Test def `basic-params` =
check(
"""|def paint(c: Int, f: String, d: List[String]) = ???
|val _ = paint(1, "aa", @@)
|""".stripMargin,
"""|List[String]
|""".stripMargin
)

@Test def `basic-type-param` =
check(
"""|def paint[T](c: T) = ???
|val _ = paint[Int](@@)
|""".stripMargin,
"""|Int
|""".stripMargin
)

@Test def `type-ascription` =
check(
"""|def doo = (@@ : Double)
Expand Down Expand Up @@ -335,3 +353,60 @@ class InferExpectedTypeSuite extends BasePCSuite:
"""|String
|""".stripMargin
)

@Test def using =
check(
"""|def go(using Ordering[Int])(x: Int, y: Int): Int =
| Ordering[Int].compare(x, y)
|
|def test =
| go(???, @@)
|""".stripMargin,
"""|Int
|""".stripMargin
)

@Test def `apply-dynamic` =
check(
"""|object TypedHoleApplyDynamic {
| val obj: reflect.Selectable {
| def method(x: Int): Unit
| } = new reflect.Selectable {
| def method(x: Int): Unit = ()
| }
|
| obj.method(@@)
|}
|""".stripMargin,
"Int"
)

@Test def `apply-dynamic-2` =
check(
"""|object TypedHoleApplyDynamic {
| val obj: reflect.Selectable {
| def method[T](x: Int, y: T): Unit
| } = new reflect.Selectable {
| def method[T](x: Int, y: T): Unit = ()
| }
|
| obj.method[String](1, @@)
|}
|""".stripMargin,
"String"
)

@Test def `apply-dynamic-3` =
check(
"""|object TypedHoleApplyDynamic {
| val obj: reflect.Selectable {
| def method[T](a: Int)(x: Int, y: T): Unit
| } = new reflect.Selectable {
| def method[T](a: Int)(x: Int, y: T): Unit = ()
| }
|
| obj.method[String](1)(1, @@)
|}
|""".stripMargin,
"String"
)
26 changes: 26 additions & 0 deletions presentation-compiler/test/dotty/tools/pc/tests/completion/SingletonCompletionsSuite.scala
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Expand Up @@ -297,4 +297,30 @@ class SingletonCompletionsSuite extends BaseCompletionSuite {
"""|"foo": "foo"
|""".stripMargin
)

@Test def `type-apply` =
check(
"""|class Consumer[A]:
| def eat(a: A) = ()
|
|def test =
| Consumer[7].eat(@@)
|""".stripMargin,
"7: 7",
topLines = Some(1)
)

@Test def `type-apply-2` =
check(
"""|class Consumer[A]:
| def eat(a: A) = ()
|
|object Consumer7 extends Consumer[7]
|
|def test =
| Consumer7.eat(@@)
|""".stripMargin,
"7: 7",
topLines = Some(1)
)
}
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