Introduce FirFile.fileSession, get rid of most FirElement.session usages

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirDeclarationStatus.kt

@@ -48,9 +48,6 @@ interface FirDeclarationStatus : FirElement {
 
     val isStatic: Boolean
 
-    override val psi: PsiElement?
-        get() = null
-
     override fun <R, D> accept(visitor: FirVisitor<R, D>, data: D): R =
         visitor.visitDeclarationStatus(this, data)
 }

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirFile.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.fir.declarations
 
 import org.jetbrains.kotlin.fir.BaseTransformedType
+import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.VisitedSupertype
 import org.jetbrains.kotlin.fir.expressions.FirAnnotationContainer
 import org.jetbrains.kotlin.fir.visitors.FirVisitor
@@ -13,6 +14,11 @@ import org.jetbrains.kotlin.name.FqName
 
 @BaseTransformedType
 interface FirFile : @VisitedSupertype FirPackageFragment, FirDeclaration, FirAnnotationContainer {
+
+    @Suppress("DEPRECATION")
+    val fileSession: FirSession
+        get() = session
+
     val name: String
 
     val packageFqName: FqName

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/impl/FirDeclarationStatusImpl.kt

@@ -7,15 +7,16 @@ package org.jetbrains.kotlin.fir.declarations.impl
 
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.Visibility
+import org.jetbrains.kotlin.fir.FirAbstractElement
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.declarations.FirDeclarationStatus
 import org.jetbrains.kotlin.fir.declarations.impl.FirDeclarationStatusImpl.Modifier.*
 
 open class FirDeclarationStatusImpl(
-    final override val session: FirSession,
+    session: FirSession,
     override val visibility: Visibility,
     override val modality: Modality?
-) : FirDeclarationStatus {
+) : FirAbstractElement(session, null), FirDeclarationStatus {
     protected var flags: Int = 0
 
     private operator fun get(modifier: Modifier): Boolean = (flags and modifier.mask) != 0

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/impl/FirDefaultPropertyAccessor.kt

@@ -8,24 +8,21 @@ package org.jetbrains.kotlin.fir.declarations.impl
 import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.Visibility
-import org.jetbrains.kotlin.fir.FirElement
-import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.fir.*
 import org.jetbrains.kotlin.fir.declarations.FirPropertyAccessor
 import org.jetbrains.kotlin.fir.declarations.FirValueParameter
 import org.jetbrains.kotlin.fir.expressions.FirAnnotationCall
 import org.jetbrains.kotlin.fir.expressions.FirBlock
-import org.jetbrains.kotlin.fir.transformInplace
-import org.jetbrains.kotlin.fir.transformSingle
 import org.jetbrains.kotlin.fir.types.FirTypeRef
 import org.jetbrains.kotlin.fir.types.impl.FirImplicitUnitTypeRef
 import org.jetbrains.kotlin.fir.visitors.FirTransformer
 
 abstract class FirDefaultPropertyAccessor(
-    final override val session: FirSession,
-    final override val psi: PsiElement?,
+    session: FirSession,
+    psi: PsiElement?,
     final override val isGetter: Boolean,
     visibility: Visibility
-) : FirPropertyAccessor {
+) : FirAbstractElement(session, psi), FirPropertyAccessor {
     override var status = FirDeclarationStatusImpl(
         session, visibility, Modality.FINAL
     )

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/impl/FirResolvedImportImpl.kt

@@ -5,7 +5,7 @@
 
 package org.jetbrains.kotlin.fir.declarations.impl
 
-import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.fir.FirAbstractElement
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.declarations.FirImport
 import org.jetbrains.kotlin.fir.declarations.FirResolvedImport
@@ -14,9 +14,10 @@ import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 
 class FirResolvedImportImpl(
+    session: FirSession,
     val delegate: FirImport,
     override val resolvedFqName: ClassId
-) : FirResolvedImport, FirImport {
+) : FirAbstractElement(session, delegate.psi), FirResolvedImport, FirImport {
     override val packageFqName: FqName
         get() = resolvedFqName.packageFqName
 
@@ -31,10 +32,4 @@ class FirResolvedImportImpl(
 
     override val isAllUnder: Boolean
         get() = delegate.isAllUnder
-
-    override val psi: PsiElement?
-        get() = delegate.psi
-
-    override val session: FirSession
-        get() = delegate.session
 }

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/impl/FirResolvedPackageStarImport.kt

@@ -5,7 +5,7 @@
 
 package org.jetbrains.kotlin.fir.declarations.impl
 
-import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.fir.FirAbstractElement
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.declarations.FirImport
 import org.jetbrains.kotlin.fir.declarations.FirResolvedImport
@@ -14,9 +14,10 @@ import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 
 class FirResolvedPackageStarImport(
+    session: FirSession,
     val delegate: FirImport,
     override val packageFqName: FqName
-) : FirResolvedImport, FirImport {
+) : FirAbstractElement(session, delegate.psi), FirResolvedImport, FirImport {
     override val relativeClassName: FqName?
         get() = null
 
@@ -31,10 +32,4 @@ class FirResolvedPackageStarImport(
 
     override val isAllUnder: Boolean
         get() = delegate.isAllUnder
-
-    override val psi: PsiElement?
-        get() = delegate.psi
-
-    override val session: FirSession
-        get() = delegate.session
 }

compiler/fir/tree/src/org/jetbrains/kotlin/fir/types/impl/FirDelegatedTypeRefImpl.kt

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.fir.types.impl
 
 import org.jetbrains.kotlin.fir.FirAbstractElement
 import org.jetbrains.kotlin.fir.FirElement
+import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.expressions.FirAnnotationCall
 import org.jetbrains.kotlin.fir.expressions.FirExpression
 import org.jetbrains.kotlin.fir.transformSingle
@@ -15,9 +16,10 @@ import org.jetbrains.kotlin.fir.types.FirTypeRef
 import org.jetbrains.kotlin.fir.visitors.FirTransformer
 
 class FirDelegatedTypeRefImpl(
+    session: FirSession,
     override var typeRef: FirTypeRef,
     override var delegate: FirExpression?
-) : FirAbstractElement(typeRef.session, typeRef.psi), FirDelegatedTypeRef {
+) : FirAbstractElement(session, typeRef.psi), FirDelegatedTypeRef {
     override val annotations: List<FirAnnotationCall>
         get() = typeRef.annotations