FIR body resolve: support subject type calculation

compiler/fir/tree/src/org/jetbrains/kotlin/fir/FirRenderer.kt

@@ -13,7 +13,6 @@ import org.jetbrains.kotlin.fir.expressions.*
 import org.jetbrains.kotlin.fir.expressions.impl.FirElseIfTrueCondition
 import org.jetbrains.kotlin.fir.expressions.impl.FirExpressionStub
 import org.jetbrains.kotlin.fir.expressions.impl.FirUnitExpression
-import org.jetbrains.kotlin.fir.expressions.impl.FirWhenSubjectExpression
 import org.jetbrains.kotlin.fir.symbols.ConeCallableSymbol
 import org.jetbrains.kotlin.fir.symbols.ConeClassLikeSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirFunctionSymbol
@@ -38,7 +37,6 @@ fun ConeKotlinType.render(): String {
     return when (this) {
         is ConeTypeVariableType -> "TypeVariable(${this.lookupTag.name})"
         is ConeDefinitelyNotNullType -> "${original.render()}!"
-        is ConeKotlinErrorType -> "error: $reason"
         is ConeClassErrorType -> "class error: $reason"
         is ConeCapturedType -> "captured type: lowerType = ${lowerType?.render()}"
         is ConeClassLikeType -> {
@@ -540,6 +538,10 @@ class FirRenderer(builder: StringBuilder) : FirVisitorVoid() {
         println("}")
     }
 
+    override fun visitWhenSubjectExpression(whenSubjectExpression: FirWhenSubjectExpression) {
+        print("\$subj\$")
+    }
+
     override fun visitTryExpression(tryExpression: FirTryExpression) {
         tryExpression.annotations.renderAnnotations()
         print("try")
@@ -604,7 +606,6 @@ class FirRenderer(builder: StringBuilder) : FirVisitorVoid() {
             when (expression) {
                 is FirExpressionStub -> "STUB"
                 is FirUnitExpression -> "Unit"
-                is FirWhenSubjectExpression -> "\$subj\$"
                 is FirElseIfTrueCondition -> "else"
                 else -> "??? ${expression.javaClass}"
             }

compiler/fir/tree/src/org/jetbrains/kotlin/fir/FirWhenSubject.kt

@@ -0,0 +1,16 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir
+
+import org.jetbrains.kotlin.fir.expressions.FirWhenExpression
+
+class FirWhenSubject {
+    lateinit var whenExpression: FirWhenExpression
+
+    fun bind(expression: FirWhenExpression) {
+        whenExpression = expression
+    }
+}

compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/FirWhenSubjectExpression.kt

@@ -0,0 +1,16 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.expressions
+
+import org.jetbrains.kotlin.fir.FirWhenSubject
+import org.jetbrains.kotlin.fir.visitors.FirVisitor
+
+interface FirWhenSubjectExpression : FirExpression {
+    val whenSubject: FirWhenSubject
+
+    override fun <R, D> accept(visitor: FirVisitor<R, D>, data: D): R =
+        visitor.visitWhenSubjectExpression(this, data)
+}

compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/impl/FirWhenSubjectExpressionImpl.kt

@@ -6,11 +6,12 @@
 package org.jetbrains.kotlin.fir.expressions.impl
 
 import com.intellij.psi.PsiElement
-import org.jetbrains.kotlin.fir.FirAbstractElement
 import org.jetbrains.kotlin.fir.FirSession
-import org.jetbrains.kotlin.fir.expressions.FirExpression
+import org.jetbrains.kotlin.fir.FirWhenSubject
+import org.jetbrains.kotlin.fir.expressions.FirWhenSubjectExpression
 
-class FirWhenSubjectExpression(
+class FirWhenSubjectExpressionImpl(
     session: FirSession,
-    psi: PsiElement?
-): FirAbstractExpression(session, psi)
+    psi: PsiElement?,
+    override val whenSubject: FirWhenSubject
+) : FirAbstractExpression(session, psi), FirWhenSubjectExpression

compiler/fir/tree/visitors/org/jetbrains/kotlin/fir/visitors/FirTransformerGenerated.kt

@@ -276,6 +276,10 @@ abstract class FirTransformer<in D> : FirVisitor<CompositeTransformResult<FirEle
         return transformExpression(whenExpression, data)
     }
 
+    open fun transformWhenSubjectExpression(whenSubjectExpression: FirWhenSubjectExpression, data: D): CompositeTransformResult<FirStatement> {
+        return transformExpression(whenSubjectExpression, data)
+    }
+
     open fun transformWrappedArgumentExpression(wrappedArgumentExpression: FirWrappedArgumentExpression, data: D): CompositeTransformResult<FirStatement> {
         return transformExpression(wrappedArgumentExpression, data)
     }
@@ -752,6 +756,10 @@ abstract class FirTransformer<in D> : FirVisitor<CompositeTransformResult<FirEle
         return transformWhenExpression(whenExpression, data)
     }
 
+    final override fun visitWhenSubjectExpression(whenSubjectExpression: FirWhenSubjectExpression, data: D): CompositeTransformResult<FirElement> {
+        return transformWhenSubjectExpression(whenSubjectExpression, data)
+    }
+
     final override fun visitWhileLoop(whileLoop: FirWhileLoop, data: D): CompositeTransformResult<FirElement> {
         return transformWhileLoop(whileLoop, data)
     }

compiler/fir/tree/visitors/org/jetbrains/kotlin/fir/visitors/FirVisitorGenerated.kt

@@ -276,6 +276,10 @@ abstract class FirVisitor<out R, in D> {
         return visitExpression(whenExpression, data)
     }
 
+    open fun visitWhenSubjectExpression(whenSubjectExpression: FirWhenSubjectExpression, data: D): R {
+        return visitExpression(whenSubjectExpression, data)
+    }
+
     open fun visitWrappedArgumentExpression(wrappedArgumentExpression: FirWrappedArgumentExpression, data: D): R {
         return visitExpression(wrappedArgumentExpression, data)
     }

compiler/fir/tree/visitors/org/jetbrains/kotlin/fir/visitors/FirVisitorVoidGenerated.kt

@@ -276,6 +276,10 @@ abstract class FirVisitorVoid : FirVisitor<Unit, Nothing?>() {
         visitExpression(whenExpression, null)
     }
 
+    open fun visitWhenSubjectExpression(whenSubjectExpression: FirWhenSubjectExpression) {
+        visitExpression(whenSubjectExpression, null)
+    }
+
     open fun visitWrappedArgumentExpression(wrappedArgumentExpression: FirWrappedArgumentExpression) {
         visitExpression(wrappedArgumentExpression, null)
     }
@@ -752,6 +756,10 @@ abstract class FirVisitorVoid : FirVisitor<Unit, Nothing?>() {
         visitWhenExpression(whenExpression)
     }
 
+    final override fun visitWhenSubjectExpression(whenSubjectExpression: FirWhenSubjectExpression, data: Nothing?) {
+        visitWhenSubjectExpression(whenSubjectExpression)
+    }
+
     final override fun visitWhileLoop(whileLoop: FirWhileLoop, data: Nothing?) {
         visitWhileLoop(whileLoop)
     }