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nicolasstuckinicolasstucki
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Disallow use of PolyFunction trait in class parents
Users should only write lambdas. Fixes #10075
1 parent c81673c commit 1b4b390

20 files changed

+99
-17
lines changed

Diff for: ‎compiler/src/dotty/tools/dotc/transform/PostTyper.scala

+1
Original file line numberDiff line numberDiff line change
@@ -370,6 +370,7 @@ class PostTyper extends MacroTransform with InfoTransformer { thisPhase =>
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val callTrace = ref(call.symbol)(using ctx.withSource(pos.source)).withSpan(pos.span)
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cpy.Inlined(tree)(callTrace, transformSub(bindings), transform(expansion)(using inlineContext(tree)))
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case templ: Template =>
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Checking.checkPolyFunctionExtension(templ)
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withNoCheckNews(templ.parents.flatMap(newPart)) {
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forwardParamAccessors(templ)
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synthMbr.addSyntheticMembers(

Diff for: ‎compiler/src/dotty/tools/dotc/typer/Checking.scala

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@@ -849,6 +849,14 @@ object Checking {
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def reportNoRefinements(pos: SrcPos) =
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report.error("PolyFunction subtypes must refine the apply method", pos)
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}.traverse(tree)
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/** Check that users do not extend the `PolyFunction` trait.
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* We only allow compiler generated `PolyFunction`s.
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*/
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def checkPolyFunctionExtension(templ: Template)(using Context): Unit =
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templ.parents.find(_.tpe.derivesFrom(defn.PolyFunctionClass)) match
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case Some(parent) => report.error(s"`PolyFunction` marker trait is reserved for compiler generated refinements", parent.srcPos)
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case None =>
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}
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trait Checking {

Diff for: ‎tests/run/erased-15.scala renamed to ‎tests/neg/erased-15.scala

+1-1
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@@ -12,7 +12,7 @@ object Test {
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}
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}
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15-
class Foo extends PolyFunction {
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class Foo extends PolyFunction { // error
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def apply(erased x: Int): Int = {
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println("Foo.apply")
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42

Diff for: ‎tests/neg/i10075.check

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@@ -0,0 +1,32 @@
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-- Error: tests/neg/i10075.scala:8:24 ----------------------------------------------------------------------------------
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8 |trait PolyTrait extends PolyFunction // error
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| ^^^^^^^^^^^^
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| `PolyFunction` marker trait is reserved for compiler generated refinements
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-- Error: tests/neg/i10075.scala:10:24 ---------------------------------------------------------------------------------
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10 |class PolyClass extends PolyTrait { // error
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| ^^^^^^^^^
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| `PolyFunction` marker trait is reserved for compiler generated refinements
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-- Error: tests/neg/i10075.scala:14:26 ---------------------------------------------------------------------------------
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14 |object PolyObject extends PolyFunction // error
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| ^^^^^^^^^^^^
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| `PolyFunction` marker trait is reserved for compiler generated refinements
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-- Error: tests/neg/i10075.scala:2:14 ----------------------------------------------------------------------------------
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2 |val foo = new PolyFunction { } // error
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| ^^^^^^^^^^^^
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| `PolyFunction` marker trait is reserved for compiler generated refinements
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-- Error: tests/neg/i10075.scala:3:14 ----------------------------------------------------------------------------------
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3 |val bar = new PolyFunction { def bar = 23 } // error
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| ^^^^^^^^^^^^
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| `PolyFunction` marker trait is reserved for compiler generated refinements
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-- Error: tests/neg/i10075.scala:4:14 ----------------------------------------------------------------------------------
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4 |val baz = new PolyFunction { def apply = 23 } // error
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| ^^^^^^^^^^^^
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| `PolyFunction` marker trait is reserved for compiler generated refinements
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-- Error: tests/neg/i10075.scala:5:14 ----------------------------------------------------------------------------------
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5 |val qux = new PolyFunction { def apply[T] = 47 } // error
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| ^^^^^^^^^^^^
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| `PolyFunction` marker trait is reserved for compiler generated refinements
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-- Error: tests/neg/i10075.scala:6:15 ----------------------------------------------------------------------------------
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6 |val quxx = new PolyFunction { def apply[T](x: T): T = x } // error
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| ^^^^^^^^^^^^
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| `PolyFunction` marker trait is reserved for compiler generated refinements

Diff for: ‎tests/neg/i10075.scala

+14
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,14 @@
1+
val poly = [T] => (x: T) => x
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val foo = new PolyFunction { } // error
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val bar = new PolyFunction { def bar = 23 } // error
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val baz = new PolyFunction { def apply = 23 } // error
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val qux = new PolyFunction { def apply[T] = 47 } // error
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val quxx = new PolyFunction { def apply[T](x: T): T = x } // error
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trait PolyTrait extends PolyFunction // error
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class PolyClass extends PolyTrait { // error
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def apply[T](x: T): T = x
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}
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object PolyObject extends PolyFunction // error

Diff for: ‎tests/neg/i10369.scala

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@@ -0,0 +1,10 @@
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type Upgrade[T] = T match
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case Int => Double
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case Char => String
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case Boolean => Boolean
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val upgrade: [t] => t => Upgrade[t] = new PolyFunction: // error
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def apply[T](x: T): Upgrade[T] = x match
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case x: Int => x.toDouble
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case x: Char => x.toString
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case x: Boolean => !x

Diff for: ‎tests/pos/i18302a.scala renamed to ‎tests/neg/i18302a.scala

+1-1
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@@ -1,4 +1,4 @@
11
def test = polyFun(1)
22

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def polyFun: PolyFunction { def apply(x: Int): Int } =
4-
new PolyFunction { def apply(x: Int): Int = x + 1 }
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new PolyFunction { def apply(x: Int): Int = x + 1 } // error

Diff for: ‎tests/neg/i18302b.check

+4
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@@ -2,3 +2,7 @@
22
3 |def polyFun: PolyFunction { def apply(x: Int)(y: Int): Int } = // error
33
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
44
|Implementation restriction: PolyFunction apply must have exactly one parameter list and optionally type arguments. No by-name nor varags are allowed.
5+
-- Error: tests/neg/i18302b.scala:4:6 ----------------------------------------------------------------------------------
6+
4 | new PolyFunction: // error
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| ^^^^^^^^^^^^
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| `PolyFunction` marker trait is reserved for compiler generated refinements

Diff for: ‎tests/neg/i18302b.scala

+1-1
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@@ -1,5 +1,5 @@
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def test = polyFun(1)(2)
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33
def polyFun: PolyFunction { def apply(x: Int)(y: Int): Int } = // error
4-
new PolyFunction:
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new PolyFunction: // error
55
def apply(x: Int)(y: Int): Int = x + y

Diff for: ‎tests/neg/i18302c.check

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@@ -2,3 +2,7 @@
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4 |def polyFun: PolyFunction { def foo(x: Int): Int } = // error
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| ^^^^^^^^^^^^^^^^^^^^
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| PolyFunction only supports apply method refinements
5+
-- Error: tests/neg/i18302c.scala:5:6 ----------------------------------------------------------------------------------
6+
5 | new PolyFunction { def foo(x: Int): Int = x + 1 } // error
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| ^^^^^^^^^^^^
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| `PolyFunction` marker trait is reserved for compiler generated refinements

Diff for: ‎tests/neg/i18302c.scala

+1-1
Original file line numberDiff line numberDiff line change
@@ -2,4 +2,4 @@ import scala.reflect.Selectable.reflectiveSelectable
22

33
def test = polyFun.foo(1)
44
def polyFun: PolyFunction { def foo(x: Int): Int } = // error
5-
new PolyFunction { def foo(x: Int): Int = x + 1 }
5+
new PolyFunction { def foo(x: Int): Int = x + 1 } // error

Diff for: ‎tests/neg/i18302d.check

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@@ -2,3 +2,7 @@
22
1 |def polyFun: PolyFunction { def apply: Int } = // error
33
| ^^^^^^^^^^^^^^
44
|Implementation restriction: PolyFunction apply must have exactly one parameter list and optionally type arguments. No by-name nor varags are allowed.
5+
-- Error: tests/neg/i18302d.scala:2:6 ----------------------------------------------------------------------------------
6+
2 | new PolyFunction { def apply: Int = 1 } // error
7+
| ^^^^^^^^^^^^
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| `PolyFunction` marker trait is reserved for compiler generated refinements

Diff for: ‎tests/neg/i18302d.scala

+1-1
Original file line numberDiff line numberDiff line change
@@ -1,2 +1,2 @@
11
def polyFun: PolyFunction { def apply: Int } = // error
2-
new PolyFunction { def apply: Int = 1 }
2+
new PolyFunction { def apply: Int = 1 } // error

Diff for: ‎tests/neg/i18302e.check

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Original file line numberDiff line numberDiff line change
@@ -2,6 +2,10 @@
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1 |def polyFun: PolyFunction { } = // error
33
| ^^^^^^^^^^^^^^^^^
44
| PolyFunction subtypes must refine the apply method
5+
-- Error: tests/neg/i18302e.scala:2:6 ----------------------------------------------------------------------------------
6+
2 | new PolyFunction { } // error
7+
| ^^^^^^^^^^^^
8+
| `PolyFunction` marker trait is reserved for compiler generated refinements
59
-- Error: tests/neg/i18302e.scala:4:15 ---------------------------------------------------------------------------------
610
4 |def polyFun(f: PolyFunction { }) = () // error
711
| ^^^^^^^^^^^^^^^^^

Diff for: ‎tests/neg/i18302e.scala

+1-1
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@@ -1,4 +1,4 @@
11
def polyFun: PolyFunction { } = // error
2-
new PolyFunction { }
2+
new PolyFunction { } // error
33

44
def polyFun(f: PolyFunction { }) = () // error

Diff for: ‎tests/neg/i18302f.check

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@@ -2,6 +2,10 @@
22
1 |def polyFun: PolyFunction = // error
33
| ^^^^^^^^^^^^
44
| PolyFunction subtypes must refine the apply method
5+
-- Error: tests/neg/i18302f.scala:2:6 ----------------------------------------------------------------------------------
6+
2 | new PolyFunction { } // error
7+
| ^^^^^^^^^^^^
8+
| `PolyFunction` marker trait is reserved for compiler generated refinements
59
-- Error: tests/neg/i18302f.scala:4:16 ---------------------------------------------------------------------------------
610
4 |def polyFun2(a: PolyFunction) = () // error
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| ^^^^^^^^^^^^
@@ -10,3 +14,7 @@
1014
6 |val polyFun3: PolyFunction = // error
1115
| ^^^^^^^^^^^^
1216
| PolyFunction subtypes must refine the apply method
17+
-- Error: tests/neg/i18302f.scala:7:6 ----------------------------------------------------------------------------------
18+
7 | new PolyFunction { } // error
19+
| ^^^^^^^^^^^^
20+
| `PolyFunction` marker trait is reserved for compiler generated refinements

Diff for: ‎tests/neg/i18302f.scala

+2-2
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,7 @@
11
def polyFun: PolyFunction = // error
2-
new PolyFunction { }
2+
new PolyFunction { } // error
33

44
def polyFun2(a: PolyFunction) = () // error
55

66
val polyFun3: PolyFunction = // error
7-
new PolyFunction { }
7+
new PolyFunction { } // error

Diff for: ‎tests/neg/i18302j.scala

+2-2
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
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def polyFunByName: PolyFunction { def apply(thunk: => Int): Int } = // error
2-
new PolyFunction { def apply(thunk: => Int): Int = 1 }
2+
new PolyFunction { def apply(thunk: => Int): Int = 1 } // error
33

44
def polyFunVarArgs: PolyFunction { def apply(args: Int*): Int } = // error
5-
new PolyFunction { def apply(thunk: Int*): Int = 1 }
5+
new PolyFunction { def apply(thunk: Int*): Int = 1 } // error

Diff for: ‎tests/pos/i10369.scala

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Original file line numberDiff line numberDiff line change
@@ -3,12 +3,6 @@ type Upgrade[T] = T match
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case Char => String
44
case Boolean => Boolean
55

6-
val upgrade: [t] => t => Upgrade[t] = new PolyFunction:
7-
def apply[T](x: T): Upgrade[T] = x match
8-
case x: Int => x.toDouble
9-
case x: Char => x.toString
10-
case x: Boolean => !x
11-
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val upgrade2: [t] => t => Upgrade[t] = [t] => (x: t) => x match
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case x: Int => x.toDouble
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case x: Char => x.toString

Diff for: ‎tests/run/erased-15.check

-1
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