Merge pull request #3915 from dotty-staging/fix-#3900

Fix #3900: add check for inline class parameters

Author: odersky

compiler/src/dotty/tools/dotc/reporting/diagnostic/ErrorMessageID.java

@@ -125,6 +125,7 @@ public enum ErrorMessageID {
     UnableToEmitSwitchID,
     MissingCompanionForStaticID,
     PolymorphicMethodMissingTypeInParentID,
+    ParamsNoInlineID,
     ;
 
     public int errorNumber() {

compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala

@@ -2069,4 +2069,11 @@ object messages {
           |$rsym does not override any method in $parentSym. Structural refinement does not allow for
           |polymorphic methods."""
   }
+
+  case class ParamsNoInline(owner: Symbol)(implicit ctx: Context)
+    extends Message(ParamsNoInlineID) {
+    val kind = "Syntax"
+    val msg = hl"""${"inline"} modifier cannot be used for a ${owner.showKind} parameter"""
+    val explanation = ""
+  }
 }

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

@@ -341,6 +341,9 @@ object Checking {
       if (!ok && !sym.is(Synthetic))
         fail(i"modifier `$flag` is not allowed for this definition")
 
+    if (sym.is(Inline) && ((sym.is(ParamAccessor) && sym.owner.isClass) || sym.is(TermParam) && sym.owner.isClassConstructor))
+      fail(ParamsNoInline(sym.owner))
+
     if (sym.is(ImplicitCommon)) {
       if (sym.owner.is(Package))
         fail(TopLevelCantBeImplicit(sym))

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

@@ -925,7 +925,7 @@ class Namer { typer: Typer =>
         }
       }
 
-     addAnnotations(denot.symbol, original)
+      addAnnotations(denot.symbol, original)
 
       val selfInfo =
         if (self.isEmpty) NoType

tests/neg/i3900.scala

@@ -0,0 +1,7 @@
+class Foo(inline val i: Int) // error
+case class Foo2(inline val i: Int) // error
+class Foo3(inline val i: Int) extends AnyVal // error
+trait Foo4(inline val i: Int) // error
+class Foo5() {
+  def this(inline x: Int) = this() // error
+}

tests/neg/inlinevals.scala

@@ -7,7 +7,7 @@ object Test {
 
   inline inline val twice = 30 // error: repeated modifier
 
-  class C(inline x: Int, private inline val y: Int) {
+  class C(inline x: Int, private inline val y: Int) { // error // error
     inline val foo: Int // error: abstract member may not be inline
     inline def bar: Int // error: abstract member may not be inline
   }