Fix Scala 2 TASTy accessors in inline patterns reduction

Author: nicolasstucki

.github/workflows/ci.yaml

@@ -143,7 +143,7 @@ jobs:
           ./project/scripts/sbt ";sjsSandbox/run ;sjsSandbox/test ;sjsJUnitTests/test ;set sjsJUnitTests/scalaJSLinkerConfig ~= switchToESModules ;sjsJUnitTests/test ;sjsCompilerTests/test"
 
       - name: Test with Scala 2 library TASTy
-        run: ./project/scripts/sbt ";set ThisBuild/Build.useScala2LibraryTasty := true ;scala3-bootstrapped/testCompilation i5" # only test a subset of test to avoid doubling the CI execution time
+        run: ./project/scripts/sbt ";set ThisBuild/Build.useScala2LibraryTasty := true ;scala3-bootstrapped/testCompilation i5; scala3-bootstrapped/testCompilation tests/run/typelevel-peano.scala" # only test a subset of test to avoid doubling the CI execution time
 
   test_windows_fast:
     runs-on: [self-hosted, Windows]

compiler/src/dotty/tools/dotc/inlines/InlineReducer.scala

@@ -329,8 +329,9 @@ class InlineReducer(inliner: Inliner)(using Context):
               val paramCls = paramType.classSymbol
               if (paramCls.is(Case) && unapp.symbol.is(Synthetic) && scrut <:< paramType) {
                 val caseAccessors =
-                  if (paramCls.is(Scala2x)) paramCls.caseAccessors.filter(_.is(Method))
-                  else paramCls.asClass.paramAccessors
+                  if !paramCls.is(Scala2x) then paramCls.asClass.paramAccessors
+                  else if paramCls.is(Scala2Tasty) then paramCls.caseAccessors
+                  else paramCls.caseAccessors.filter(_.is(Method))
                 val selectors =
                   for (accessor <- caseAccessors)
                   yield constToLiteral(reduceProjection(ref(scrut).select(accessor).ensureApplied))