Change 'private, protected, or this expected' to Message

3 files changed, 19 insertions, 3 deletions

diff --git a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
index c14108d2e..f9187c5fe 100644
--- a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
+++ b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -1607,6 +1607,7 @@ object Parsers {
      *  LocalModifier  ::= abstract | final | sealed | implicit | lazy
      */
     def modifiers(allowed: BitSet = modifierTokens, start: Modifiers = Modifiers()): Modifiers = {
+      @tailrec
       def loop(mods: Modifiers): Modifiers = {
         if (allowed contains in.token) {
           val isAccessMod = accessModifierTokens contains in.token
@@ -2057,7 +2058,7 @@ object Parsers {
       val name = ident().toTypeName
       val constr = atPos(in.lastOffset) {
         val tparams = typeParamClauseOpt(ParamOwner.Class)
-        val cmods = constrModsOpt()
+        val cmods = constrModsOpt(name)
         val vparamss = paramClauses(name, mods is Case)
 
         makeConstructor(tparams, vparamss).withMods(cmods)
@@ -2070,11 +2071,11 @@ object Parsers {
     /** ConstrMods        ::=  AccessModifier
      *                      |  Annotation {Annotation} (AccessModifier | `this')
      */
-    def constrModsOpt(): Modifiers = {
+    def constrModsOpt(owner: Name): Modifiers = {
       val mods = modifiers(accessModifierTokens, annotsAsMods())
       if (mods.hasAnnotations && !mods.hasFlags)
         if (in.token == THIS) in.nextToken()
-        else syntaxError("`private', `protected', or `this' expected")
+        else syntaxError(AnnotatedPrimaryConstructorRequiresModifierOrThis(owner))
       mods
     }
 
diff --git a/compiler/src/dotty/tools/dotc/reporting/diagnostic/ErrorMessageID.java b/compiler/src/dotty/tools/dotc/reporting/diagnostic/ErrorMessageID.java
index 2bf15cb7c..bbd93eb30 100644
--- a/compiler/src/dotty/tools/dotc/reporting/diagnostic/ErrorMessageID.java
+++ b/compiler/src/dotty/tools/dotc/reporting/diagnostic/ErrorMessageID.java
@@ -51,6 +51,7 @@ public enum ErrorMessageID {
     ExpectedTokenButFoundID,
     MixedLeftAndRightAssociativeOpsID,
     CantInstantiateAbstractClassOrTraitID,
+    AnnotatedPrimaryConstructorRequiresModifierOrThisID,
     ;
 
     public int errorNumber() {
diff --git a/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 34190c114..e367e9ab2 100644
--- a/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -1146,4 +1146,18 @@ object messages {
            |""".stripMargin
   }
 
+  case class AnnotatedPrimaryConstructorRequiresModifierOrThis(cls: Name)(implicit ctx: Context)
+    extends Message(AnnotatedPrimaryConstructorRequiresModifierOrThisID) {
+    val kind = "Syntax"
+    val msg = hl"""${"private"}, ${"protected"}, or ${"this"} expected for annotated primary constructor"""
+    val explanation =
+      hl"""|When using annotations with a primary constructor of a class,
+           |the annotation must be followed by an access modifier
+           |(${"private"} or ${"protected"}) or ${"this"}.
+           |
+           |For example:
+           |  ${"class Sample @deprecated this(param: Parameter) { ..."}
+           |                           ^^^^
+           |""".stripMargin
+  }
 }