From 0ce5de51db6d657e3561b314a227114f70ba75e9 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Mon, 9 May 2022 17:49:59 +0200
Subject: [PATCH] Fix check experimental inline references

We where not checking if the current scope was an experimental scope

Fixes #15133
---
 .../tools/dotc/typer/CrossVersionChecks.scala  | 18 +++++++++++-------
 .../src/dotty/tools/dotc/typer/Inliner.scala   |  5 ++---
 .../no-experimental/i15133a.scala              | 15 +++++++++++++++
 .../no-experimental/i15133b.scala              | 13 +++++++++++++
 4 files changed, 41 insertions(+), 10 deletions(-)
 create mode 100644 tests/pos-custom-args/no-experimental/i15133a.scala
 create mode 100644 tests/pos-custom-args/no-experimental/i15133b.scala

diff --git a/compiler/src/dotty/tools/dotc/typer/CrossVersionChecks.scala b/compiler/src/dotty/tools/dotc/typer/CrossVersionChecks.scala
index c2b8c79666f4..a807d8299b41 100644
--- a/compiler/src/dotty/tools/dotc/typer/CrossVersionChecks.scala
+++ b/compiler/src/dotty/tools/dotc/typer/CrossVersionChecks.scala
@@ -12,6 +12,7 @@ import ast.tpd
 
 class CrossVersionChecks extends MiniPhase:
   import tpd.*
+  import CrossVersionChecks.*
 
   override def phaseName: String = CrossVersionChecks.name
 
@@ -27,7 +28,7 @@ class CrossVersionChecks extends MiniPhase:
   // arbitrarily choose one as more important than the other.
   private def checkUndesiredProperties(sym: Symbol, pos: SrcPos)(using Context): Unit =
     checkDeprecated(sym, pos)
-    checkExperimental(sym, pos)
+    checkExperimentalRef(sym, pos)
     checkSinceAnnot(sym, pos)
 
     val xMigrationValue = ctx.settings.Xmigration.value
@@ -69,10 +70,6 @@ class CrossVersionChecks extends MiniPhase:
         val since = annot.argumentConstant(1).map(" since " + _.stringValue).getOrElse("")
         report.deprecationWarning(s"${sym.showLocated} is deprecated${since}${msg}", pos)
 
-  private def checkExperimental(sym: Symbol, pos: SrcPos)(using Context): Unit =
-    if sym.isExperimental && !ctx.owner.isInExperimentalScope then
-      Feature.checkExperimentalDef(sym, pos)
-
   private def checkExperimentalSignature(sym: Symbol, pos: SrcPos)(using Context): Unit =
     class Checker extends TypeTraverser:
       def traverse(tp: Type): Unit =
@@ -192,11 +189,11 @@ class CrossVersionChecks extends MiniPhase:
     tpe.foreachPart {
       case TypeRef(_, sym: Symbol)  =>
         checkDeprecated(sym, tree.srcPos)
-        checkExperimental(sym, tree.srcPos)
+        checkExperimentalRef(sym, tree.srcPos)
         checkSinceAnnot(sym, tree.srcPos)
       case TermRef(_, sym: Symbol)  =>
         checkDeprecated(sym, tree.srcPos)
-        checkExperimental(sym, tree.srcPos)
+        checkExperimentalRef(sym, tree.srcPos)
         checkSinceAnnot(sym, tree.srcPos)
       case _ =>
     }
@@ -214,3 +211,10 @@ end CrossVersionChecks
 object CrossVersionChecks:
   val name: String = "crossVersionChecks"
   val description: String = "check issues related to deprecated and experimental"
+
+  /** Check that a reference to an experimental definition with symbol `sym` is only
+   *  used in an experimental scope
+   */
+  def checkExperimentalRef(sym: Symbol, pos: SrcPos)(using Context): Unit =
+    if sym.isExperimental && !ctx.owner.isInExperimentalScope then
+      Feature.checkExperimentalDef(sym, pos)
diff --git a/compiler/src/dotty/tools/dotc/typer/Inliner.scala b/compiler/src/dotty/tools/dotc/typer/Inliner.scala
index b1f4eb0b00ba..3421e633ac03 100644
--- a/compiler/src/dotty/tools/dotc/typer/Inliner.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Inliner.scala
@@ -25,7 +25,7 @@ import ErrorReporting.errorTree
 import dotty.tools.dotc.util.{SimpleIdentityMap, SimpleIdentitySet, SourceFile, SourcePosition, SrcPos}
 import dotty.tools.dotc.parsing.Parsers.Parser
 import Nullables._
-import transform.{PostTyper, Inlining}
+import transform.{PostTyper, Inlining, CrossVersionChecks}
 
 import collection.mutable
 import reporting.trace
@@ -102,8 +102,7 @@ object Inliner {
       if (tree.symbol == defn.CompiletimeTesting_typeChecks) return Intrinsics.typeChecks(tree)
       if (tree.symbol == defn.CompiletimeTesting_typeCheckErrors) return Intrinsics.typeCheckErrors(tree)
 
-    if tree.symbol.isExperimental then
-      Feature.checkExperimentalDef(tree.symbol, tree)
+    CrossVersionChecks.checkExperimentalRef(tree.symbol, tree.srcPos)
 
     if tree.symbol.isConstructor then return tree // error already reported for the inline constructor definition
 
diff --git a/tests/pos-custom-args/no-experimental/i15133a.scala b/tests/pos-custom-args/no-experimental/i15133a.scala
new file mode 100644
index 000000000000..c7f55f7838c7
--- /dev/null
+++ b/tests/pos-custom-args/no-experimental/i15133a.scala
@@ -0,0 +1,15 @@
+import scala.annotation.experimental
+
+@experimental
+inline def foo: Any = ???
+
+@experimental
+object Test {
+  val x = foo
+
+  def bar() = {
+    foo
+  }
+
+  foo
+}
diff --git a/tests/pos-custom-args/no-experimental/i15133b.scala b/tests/pos-custom-args/no-experimental/i15133b.scala
new file mode 100644
index 000000000000..d14d6e84cf6e
--- /dev/null
+++ b/tests/pos-custom-args/no-experimental/i15133b.scala
@@ -0,0 +1,13 @@
+import scala.annotation.experimental
+
+@experimental
+inline def foo: Any = ???
+
+object Test {
+  @experimental val x = foo
+
+  @experimental
+  def bar() = {
+    foo
+  }
+}