Light classes should reuse language versions settings during generation

#KT-26732 Fixed

compiler/light-classes/src/org/jetbrains/kotlin/asJava/builder/LightClassBuilder.kt

@@ -28,7 +28,7 @@ import com.intellij.psi.impl.java.stubs.PsiJavaFileStub
 import com.intellij.psi.impl.java.stubs.impl.PsiJavaFileStubImpl
 import com.intellij.psi.impl.source.tree.TreeElement
 import org.jetbrains.kotlin.codegen.state.GenerationState
-import org.jetbrains.kotlin.config.CompilerConfiguration
+import org.jetbrains.kotlin.config.*
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.resolve.BindingContext
@@ -54,7 +54,13 @@ fun buildLightClass(
                 context.module,
                 context.bindingContext,
                 files.toList(),
-                CompilerConfiguration.EMPTY
+                context.languageVersionSettings?.let {
+                    CompilerConfiguration().apply {
+                        languageVersionSettings = it
+                        isReadOnly = true
+                    }
+                } ?: CompilerConfiguration.EMPTY
+
         ).generateDeclaredClassFilter(generateClassFilter).wantsDiagnostics(false).build()
         state.beforeCompile()
 

compiler/light-classes/src/org/jetbrains/kotlin/asJava/builder/LightClassBuilder.kt.173

@@ -30,7 +30,7 @@ import com.intellij.psi.impl.java.stubs.PsiJavaFileStub
 import com.intellij.psi.impl.java.stubs.impl.PsiJavaFileStubImpl
 import com.intellij.psi.impl.source.tree.TreeElement
 import org.jetbrains.kotlin.codegen.state.GenerationState
-import org.jetbrains.kotlin.config.CompilerConfiguration
+import org.jetbrains.kotlin.config.*
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.resolve.BindingContext
@@ -56,7 +56,12 @@ fun buildLightClass(
                 context.module,
                 context.bindingContext,
                 files.toList(),
-                CompilerConfiguration.EMPTY
+                context.languageVersionSettings?.let {
+                    CompilerConfiguration().apply {
+                        languageVersionSettings = it
+                        isReadOnly = true
+                    }
+                } ?: CompilerConfiguration.EMPTY
         ).generateDeclaredClassFilter(generateClassFilter).wantsDiagnostics(false).build()
         state.beforeCompile()
 

compiler/light-classes/src/org/jetbrains/kotlin/asJava/builder/LightClassConstructionContext.kt

@@ -16,10 +16,12 @@
 
 package org.jetbrains.kotlin.asJava.builder
 
+import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.descriptors.ModuleDescriptor
 import org.jetbrains.kotlin.resolve.BindingContext
 
 open class LightClassConstructionContext(
         val bindingContext: BindingContext,
-        val module: ModuleDescriptor
+        val module: ModuleDescriptor,
+        val languageVersionSettings: LanguageVersionSettings? = null
 )