[FIX] Add the ExplicitBackingFields language feature

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/runners/AbstractFirDiagnosticTest.kt

@@ -17,6 +17,7 @@ import org.jetbrains.kotlin.test.directives.FirDiagnosticsDirectives.WITH_EXTEND
 import org.jetbrains.kotlin.test.directives.JvmEnvironmentConfigurationDirectives.JDK_KIND
 import org.jetbrains.kotlin.test.directives.JvmEnvironmentConfigurationDirectives.WITH_REFLECT
 import org.jetbrains.kotlin.test.directives.JvmEnvironmentConfigurationDirectives.WITH_STDLIB
+import org.jetbrains.kotlin.test.directives.LanguageSettingsDirectives.LANGUAGE
 import org.jetbrains.kotlin.test.frontend.fir.FirFailingTestSuppressor
 import org.jetbrains.kotlin.test.frontend.fir.FirFrontendFacade
 import org.jetbrains.kotlin.test.frontend.fir.FirOutputArtifact
@@ -123,4 +124,10 @@ fun TestConfigurationBuilder.baseFirDiagnosticTestConfiguration(
             +WITH_REFLECT
         }
     }
+
+    forTestsMatching("compiler/fir/analysis-tests/testData/resolveWithStdlib/properties/backingField/*") {
+        defaultDirectives {
+            LANGUAGE with "+ExplicitBackingFields"
+        }
+    }
 }

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/runners/codegen/AbstractBytecodeListingTest.kt

@@ -16,6 +16,7 @@ import org.jetbrains.kotlin.test.backend.ir.JvmIrBackendFacade
 import org.jetbrains.kotlin.test.builders.TestConfigurationBuilder
 import org.jetbrains.kotlin.test.builders.configureJvmArtifactsHandlersStep
 import org.jetbrains.kotlin.test.directives.CodegenTestDirectives
+import org.jetbrains.kotlin.test.directives.LanguageSettingsDirectives
 import org.jetbrains.kotlin.test.runners.AbstractKotlinCompilerWithTargetBackendTest
 import org.jetbrains.kotlin.test.frontend.classic.*
 import org.jetbrains.kotlin.test.frontend.fir.Fir2IrResultsConverter
@@ -44,6 +45,12 @@ abstract class AbstractBytecodeListingTestBase<R : ResultingArtifact.FrontendOut
         }
 
         useAfterAnalysisCheckers(::BlackBoxCodegenSuppressor)
+
+        forTestsMatching("compiler/fir/fir2ir/testData/codegen/bytecodeListing/*") {
+            defaultDirectives {
+                LanguageSettingsDirectives.LANGUAGE with "+ExplicitBackingFields"
+            }
+        }
     }
 }
 

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/runners/codegen/AbstractFirBlackBoxCodegenTest.kt

@@ -13,6 +13,7 @@ import org.jetbrains.kotlin.test.builders.TestConfigurationBuilder
 import org.jetbrains.kotlin.test.builders.configureFirHandlersStep
 import org.jetbrains.kotlin.test.directives.JvmEnvironmentConfigurationDirectives.USE_PSI_CLASS_FILES_READING
 import org.jetbrains.kotlin.test.directives.JvmEnvironmentConfigurationDirectives.WITH_STDLIB
+import org.jetbrains.kotlin.test.directives.LanguageSettingsDirectives
 import org.jetbrains.kotlin.test.frontend.fir.Fir2IrResultsConverter
 import org.jetbrains.kotlin.test.frontend.fir.FirFrontendFacade
 import org.jetbrains.kotlin.test.frontend.fir.FirMetaInfoDiffSuppressor
@@ -64,6 +65,15 @@ open class AbstractFirBlackBoxCodegenTest : AbstractJvmBlackBoxCodegenTestBase<F
             )
 
             configureDumpHandlersForCodegenTest()
+
+            forTestsMatching(
+                "compiler/fir/fir2ir/testData/codegen/box/properties/backingField/*" or
+                        "compiler/fir/fir2ir/testData/codegen/boxWithStdLib/properties/backingField/*"
+            ) {
+                defaultDirectives {
+                    LanguageSettingsDirectives.LANGUAGE with "+ExplicitBackingFields"
+                }
+            }
         }
     }
 }

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/runners/ir/AbstractIrTextTest.kt

@@ -17,6 +17,7 @@ import org.jetbrains.kotlin.test.builders.firHandlersStep
 import org.jetbrains.kotlin.test.builders.irHandlersStep
 import org.jetbrains.kotlin.test.directives.CodegenTestDirectives.DUMP_IR
 import org.jetbrains.kotlin.test.directives.CodegenTestDirectives.DUMP_KT_IR
+import org.jetbrains.kotlin.test.directives.LanguageSettingsDirectives
 import org.jetbrains.kotlin.test.frontend.classic.ClassicFrontend2IrConverter
 import org.jetbrains.kotlin.test.frontend.classic.ClassicFrontendFacade
 import org.jetbrains.kotlin.test.frontend.classic.ClassicFrontendOutputArtifact
@@ -112,6 +113,12 @@ open class AbstractFir2IrTextTest : AbstractIrTextTestBase<FirOutputArtifact>()
                 ::FirIrDumpIdenticalChecker,
                 ::BlackBoxCodegenSuppressor
             )
+
+            forTestsMatching("compiler/fir/fir2ir/testData/ir/irText/properties/backingField/*") {
+                defaultDirectives {
+                    LanguageSettingsDirectives.LANGUAGE with "+ExplicitBackingFields"
+                }
+            }
         }
     }
 }

compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt

@@ -246,6 +246,7 @@ enum class LanguageFeature(
     MultiPlatformProjects(sinceVersion = null, defaultState = State.DISABLED),
     InlineClasses(KOTLIN_1_3, defaultState = State.ENABLED_WITH_WARNING, kind = UNSTABLE_FEATURE),
     ProhibitComparisonOfIncompatibleClasses(sinceVersion = null, kind = BUG_FIX, defaultState = State.DISABLED),
+    ExplicitBackingFields(sinceVersion = null, defaultState = State.DISABLED, kind = UNSTABLE_FEATURE),
 
     ;