Check deprecation of inline methods

We must check these constraint just before inlining as later on there on
the call might completely disappear. We do the same as we did for
experimental definition checks.

Fixes #19913

Author: nicolasstucki

Diff for: compiler/src/dotty/tools/dotc/inlines/Inlines.scala

@@ -100,7 +100,7 @@ object Inlines:
     if ctx.isAfterTyper then
       // During typer we wait with cross version checks until PostTyper, in order
       // not to provoke cyclic references. See i16116 for a test case.
-      CrossVersionChecks.checkExperimentalRef(tree.symbol, tree.srcPos)
+      CrossVersionChecks.checkRef(tree.symbol, tree.srcPos)
 
     if tree.symbol.isConstructor then return tree // error already reported for the inline constructor definition
 

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

@@ -369,7 +369,7 @@ class PostTyper extends MacroTransform with InfoTransformer { thisPhase =>
           }
         case tree @ Inlined(call, bindings, expansion) if !tree.inlinedFromOuterScope =>
           val pos = call.sourcePos
-          CrossVersionChecks.checkExperimentalRef(call.symbol, pos)
+          CrossVersionChecks.checkRef(call.symbol, pos)
           withMode(Mode.NoInline)(transform(call))
           val callTrace = Inlines.inlineCallTrace(call.symbol, pos)(using ctx.withSource(pos.source))
           cpy.Inlined(tree)(callTrace, transformSub(bindings), transform(expansion)(using inlineContext(tree)))

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

@@ -24,54 +24,13 @@ class CrossVersionChecks extends MiniPhase:
   // warnings after the first, but I think it'd be better if we didn't have to
   // arbitrarily choose one as more important than the other.
   private def checkUndesiredProperties(sym: Symbol, pos: SrcPos)(using Context): Unit =
-    checkDeprecated(sym, pos)
-    checkExperimentalRef(sym, pos)
+    checkRef(sym, pos)
 
     val xMigrationValue = ctx.settings.Xmigration.value
     if xMigrationValue != NoScalaVersion then
       checkMigration(sym, pos, xMigrationValue)
   end checkUndesiredProperties
 
-  /**Skip warnings for synthetic members of case classes during declaration and
-    * scan the chain of outer declaring scopes from the current context
-    * a deprecation warning will be skipped if one the following holds
-    * for a given declaring scope:
-    * - the symbol associated with the scope is also deprecated.
-    * - if and only if `sym` is an enum case, the scope is either
-    *   a module that declares `sym`, or the companion class of the
-    *   module that declares `sym`.
-    */
-  def skipWarning(sym: Symbol)(using Context): Boolean =
-
-    /** is the owner an enum or its companion and also the owner of sym */
-    def isEnumOwner(owner: Symbol)(using Context) =
-      // pre: sym is an enumcase
-      if owner.isEnumClass then owner.companionClass eq sym.owner
-      else if owner.is(ModuleClass) && owner.companionClass.isEnumClass then owner eq sym.owner
-      else false
-
-    def isDeprecatedOrEnum(owner: Symbol)(using Context) =
-      // pre: sym is an enumcase
-      owner.isDeprecated || isEnumOwner(owner)
-
-    (ctx.owner.is(Synthetic) && sym.is(CaseClass))
-      || ctx.owner.ownersIterator.exists(if sym.isEnumCase then isDeprecatedOrEnum else _.isDeprecated)
-  end skipWarning
-
-
-  /** If @deprecated is present, and the point of reference is not enclosed
-   * in either a deprecated member or a scala bridge method, issue a warning.
-   */
-  private def checkDeprecated(sym: Symbol, pos: SrcPos)(using Context): Unit =
-
-    // Also check for deprecation of the companion class for synthetic methods
-    val toCheck = sym :: (if sym.isAllOf(SyntheticMethod) then sym.owner.companionClass :: Nil else Nil)
-    for sym <- toCheck; annot <- sym.getAnnotation(defn.DeprecatedAnnot) do
-      if !skipWarning(sym) then
-        val msg = annot.argumentConstant(0).map(": " + _.stringValue).getOrElse("")
-        val since = annot.argumentConstant(1).map(" since " + _.stringValue).getOrElse("")
-        report.deprecationWarning(em"${sym.showLocated} is deprecated${since}${msg}", pos)
-
   private def checkExperimentalAnnots(sym: Symbol)(using Context): Unit =
     if sym.exists && !sym.isInExperimentalScope then
       for annot <- sym.annotations if annot.symbol.isExperimental do
@@ -160,11 +119,11 @@ class CrossVersionChecks extends MiniPhase:
     tpe.foreachPart {
       case TypeRef(_, sym: Symbol)  =>
         if tree.span.isSourceDerived then
-          checkDeprecated(sym, tree.srcPos)
+          checkDeprecatedRef(sym, tree.srcPos)
         checkExperimentalRef(sym, tree.srcPos)
       case TermRef(_, sym: Symbol)  =>
         if tree.span.isSourceDerived then
-          checkDeprecated(sym, tree.srcPos)
+          checkDeprecatedRef(sym, tree.srcPos)
         checkExperimentalRef(sym, tree.srcPos)
       case _ =>
     }
@@ -186,9 +145,55 @@ 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` meets cross-version constraints
+   *  for `@deprecated` and `@experimental`.
+   */
+  def checkRef(sym: Symbol, pos: SrcPos)(using Context): Unit =
+    checkDeprecatedRef(sym, pos)
+    checkExperimentalRef(sym, pos)
+
   /** 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 =
+  private[CrossVersionChecks] def checkExperimentalRef(sym: Symbol, pos: SrcPos)(using Context): Unit =
     if sym.isExperimental && !ctx.owner.isInExperimentalScope then
       Feature.checkExperimentalDef(sym, pos)
+
+  /** If @deprecated is present, and the point of reference is not enclosed
+   *  in either a deprecated member or a scala bridge method, issue a warning.
+   */
+  private[CrossVersionChecks] def checkDeprecatedRef(sym: Symbol, pos: SrcPos)(using Context): Unit =
+
+    // Also check for deprecation of the companion class for synthetic methods
+    val toCheck = sym :: (if sym.isAllOf(SyntheticMethod) then sym.owner.companionClass :: Nil else Nil)
+    for sym <- toCheck; annot <- sym.getAnnotation(defn.DeprecatedAnnot) do
+      if !skipWarning(sym) then
+        val msg = annot.argumentConstant(0).map(": " + _.stringValue).getOrElse("")
+        val since = annot.argumentConstant(1).map(" since " + _.stringValue).getOrElse("")
+        report.deprecationWarning(em"${sym.showLocated} is deprecated${since}${msg}", pos)
+
+  /** Skip warnings for synthetic members of case classes during declaration and
+   *  scan the chain of outer declaring scopes from the current context
+   *  a deprecation warning will be skipped if one the following holds
+   *  for a given declaring scope:
+   *  - the symbol associated with the scope is also deprecated.
+   *  - if and only if `sym` is an enum case, the scope is either
+   *    a module that declares `sym`, or the companion class of the
+   *    module that declares `sym`.
+   */
+  private def skipWarning(sym: Symbol)(using Context): Boolean =
+
+    /** is the owner an enum or its companion and also the owner of sym */
+    def isEnumOwner(owner: Symbol)(using Context) =
+      // pre: sym is an enumcase
+      if owner.isEnumClass then owner.companionClass eq sym.owner
+      else if owner.is(ModuleClass) && owner.companionClass.isEnumClass then owner eq sym.owner
+      else false
+
+    def isDeprecatedOrEnum(owner: Symbol)(using Context) =
+      // pre: sym is an enumcase
+      owner.isDeprecated || isEnumOwner(owner)
+
+    (ctx.owner.is(Synthetic) && sym.is(CaseClass))
+      || ctx.owner.ownersIterator.exists(if sym.isEnumCase then isDeprecatedOrEnum else _.isDeprecated)
+  end skipWarning

Diff for: scaladoc-testcases/src/tests/hugetype.scala

@@ -3,6 +3,7 @@ package tests.hugetype
 import compiletime._
 import compiletime.ops.int._
 import scala.annotation.experimental
+import scala.annotation.nowarn
 
 /**
  * a particular group of people or things that share similar characteristics and form a smaller division of a larger set:
@@ -39,7 +40,7 @@ trait XD extends E:
    */
   @experimental
   @deprecated
-  protected override final implicit transparent inline abstract infix def same[A](a: A): A = a
+  protected override final implicit transparent inline abstract infix def same[A](a: A): A = a: @nowarn
 
 trait Parent[X, A[_], B[_, _]]
 

Diff for: tests/warn/i19913.check

@@ -0,0 +1,8 @@
+-- Deprecation Warning: tests/warn/i19913.scala:13:25 ------------------------------------------------------------------
+13 |  Deprecated.inlineMethod() // warn
+   |  ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |  method inlineMethod in object Deprecated is deprecated: test
+-- Deprecation Warning: tests/warn/i19913.scala:12:13 ------------------------------------------------------------------
+12 |  Deprecated.method() // warn
+   |  ^^^^^^^^^^^^^^^^^
+   |  method method in object Deprecated is deprecated: test

Diff for: tests/warn/i19913.scala

@@ -0,0 +1,13 @@
+//> using options -deprecation
+
+object Deprecated:
+
+  @deprecated("test")
+  def method() = ???
+
+  @deprecated("test")
+  inline def inlineMethod() = ???
+
+object Test:
+  Deprecated.method() // warn
+  Deprecated.inlineMethod() // warn