Fix param accessors

Author: nicolasstucki

compiler/src/dotty/tools/dotc/typer/Checking.scala

@@ -542,7 +542,8 @@ object Checking {
       if sym.is(Enum) then fail(em"@publicInBinary cannot be used on enum definitions")
       else if sym.isType && !sym.is(Module) && !(sym.is(Given) || sym.companionModule.is(Given)) then fail(em"@publicInBinary cannot be used on ${sym.showKind} definitions")
       else if !sym.owner.isClass && !(sym.is(Param) && sym.owner.isConstructor) then fail(em"@publicInBinary cannot be used on local definitions")
-      else if sym.is(Private) && !sym.privateWithin.exists && !sym.isConstructor then fail(em"@publicInBinary cannot be used on private definitions\n\nThe definition could be `private[${sym.owner.name}]` or `protected` instead")
+      else if sym.is(ParamAccessor) && sym.is(Private) then fail(em"@publicInBinary cannot be non `val` constructor parameters")
+      else if sym.is(Private) && !sym.privateWithin.exists && !sym.isConstructor then fail(em"@publicInBinary cannot be used on private definitions\n\nConsider using `private[${sym.owner.name}]` or `protected` instead")
     if (sym.hasAnnotation(defn.NativeAnnot)) {
       if (!sym.is(Deferred))
         fail(NativeMembersMayNotHaveImplementation(sym))

tests/neg/publicInBinary.check

@@ -22,6 +22,14 @@
 21 |  @publicInBinary case B(a: Int) // error
    |                       ^
    |                       @publicInBinary cannot be used on enum definitions
+-- Error: tests/neg/publicInBinary.scala:25:18 -------------------------------------------------------------------------
+25 |  @publicInBinary x: Int, // error
+   |                  ^
+   |                  @publicInBinary cannot be non `val` constructor parameters
+-- Error: tests/neg/publicInBinary.scala:26:31 -------------------------------------------------------------------------
+26 |  @publicInBinary private[Bar] y: Int, // error
+   |                               ^
+   |                               @publicInBinary cannot be non `val` constructor parameters
 -- Error: tests/neg/publicInBinary.scala:7:21 --------------------------------------------------------------------------
 7 |@publicInBinary type A // error
   |                     ^

tests/neg/publicInBinary.scala

@@ -19,3 +19,10 @@ def f(@publicInBinary x: Int) = 3 // error
 enum Enum2:
   @publicInBinary case A // error
   @publicInBinary case B(a: Int) // error
+
+
+class Bar (
+  @publicInBinary x: Int, // error
+  @publicInBinary private[Bar] y: Int, // error
+  @publicInBinary private[Bar] val z: Int,
+)

tests/run/publicInBinary/Lib_1.scala

@@ -121,7 +121,7 @@ package constructors {
   class Foo @publicInBinary private[constructors] (x: Int):
     @publicInBinary private[constructors] def this(x: Int, y: Int) = this(x + y)
 
-  class Bar @publicInBinary(@publicInBinary private[Bar] x: Int):
+  class Bar @publicInBinary(@publicInBinary private[Bar] val x: Int):
     @publicInBinary private def this(x: Int, y: Int) = this(x + y)
     inline def bar: Bar = new Bar(x, x)