Raw FIR: introduce string concatenation call

This removes some 'plus' calls to be resolved

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

@@ -641,6 +641,11 @@ class FirRenderer(builder: StringBuilder) : FirVisitorVoid() {
         print(")")
     }
 
+    override fun visitStringConcatenationCall(stringConcatenationCall: FirStringConcatenationCall) {
+        print("<strcat>")
+        visitCall(stringConcatenationCall)
+    }
+
     override fun visitTypeOperatorCall(typeOperatorCall: FirTypeOperatorCall) {
         print("(")
         typeOperatorCall.argument.accept(this)

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

@@ -0,0 +1,13 @@
+/*
+ * 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.visitors.FirVisitor
+
+interface FirStringConcatenationCall : FirCall {
+    override fun <R, D> accept(visitor: FirVisitor<R, D>, data: D): R =
+        visitor.visitStringConcatenationCall(this, data)
+}

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

@@ -0,0 +1,19 @@
+/*
+ * 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.impl
+
+import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.fir.expressions.FirStringConcatenationCall
+import org.jetbrains.kotlin.fir.types.FirTypeRef
+import org.jetbrains.kotlin.fir.types.impl.FirImplicitStringTypeRef
+
+class FirStringConcatenationCallImpl(
+    session: FirSession,
+    psi: PsiElement?
+) : FirAbstractCall(session, psi), FirStringConcatenationCall {
+    override var typeRef: FirTypeRef = FirImplicitStringTypeRef(session, psi)
+}

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

@@ -63,3 +63,8 @@ class FirImplicitNothingTypeRef(
     psi: PsiElement?
 ) : FirImplicitBuiltinTypeRef(session, psi, StandardClassIds.Nothing)
 
+class FirImplicitStringTypeRef(
+    session: FirSession,
+    psi: PsiElement?
+) : FirImplicitBuiltinTypeRef(session, psi, StandardClassIds.String)
+

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

@@ -232,6 +232,10 @@ abstract class FirTransformer<in D> : FirVisitor<CompositeTransformResult<FirEle
         return transformOperatorCall(typeOperatorCall, data)
     }
 
+    open fun transformStringConcatenationCall(stringConcatenationCall: FirStringConcatenationCall, data: D): CompositeTransformResult<FirStatement> {
+        return transformCall(stringConcatenationCall, data)
+    }
+
     open fun transformClassReferenceExpression(classReferenceExpression: FirClassReferenceExpression, data: D): CompositeTransformResult<FirStatement> {
         return transformExpression(classReferenceExpression, data)
     }
@@ -668,6 +672,10 @@ abstract class FirTransformer<in D> : FirVisitor<CompositeTransformResult<FirEle
         return transformStatement(statement, data)
     }
 
+    final override fun visitStringConcatenationCall(stringConcatenationCall: FirStringConcatenationCall, data: D): CompositeTransformResult<FirElement> {
+        return transformStringConcatenationCall(stringConcatenationCall, data)
+    }
+
     final override fun visitSuperReference(superReference: FirSuperReference, data: D): CompositeTransformResult<FirElement> {
         return transformSuperReference(superReference, data)
     }

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

@@ -232,6 +232,10 @@ abstract class FirVisitor<out R, in D> {
         return visitOperatorCall(typeOperatorCall, data)
     }
 
+    open fun visitStringConcatenationCall(stringConcatenationCall: FirStringConcatenationCall, data: D): R {
+        return visitCall(stringConcatenationCall, data)
+    }
+
     open fun visitClassReferenceExpression(classReferenceExpression: FirClassReferenceExpression, data: D): R {
         return visitExpression(classReferenceExpression, data)
     }

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

@@ -232,6 +232,10 @@ abstract class FirVisitorVoid : FirVisitor<Unit, Nothing?>() {
         visitOperatorCall(typeOperatorCall, null)
     }
 
+    open fun visitStringConcatenationCall(stringConcatenationCall: FirStringConcatenationCall) {
+        visitCall(stringConcatenationCall, null)
+    }
+
     open fun visitClassReferenceExpression(classReferenceExpression: FirClassReferenceExpression) {
         visitExpression(classReferenceExpression, null)
     }
@@ -668,6 +672,10 @@ abstract class FirVisitorVoid : FirVisitor<Unit, Nothing?>() {
         visitStatement(statement)
     }
 
+    final override fun visitStringConcatenationCall(stringConcatenationCall: FirStringConcatenationCall, data: Nothing?) {
+        visitStringConcatenationCall(stringConcatenationCall)
+    }
+
     final override fun visitSuperReference(superReference: FirSuperReference, data: Nothing?) {
         visitSuperReference(superReference)
     }