Raw FIR: introduce string concatenation call

This removes some 'plus' calls to be resolved

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrVisitor.kt

@@ -80,6 +80,8 @@ internal class Fir2IrVisitor(
 
     private val booleanType = FirImplicitBooleanTypeRef(session, null).toIrType(session, declarationStorage)
 
+    private val stringType = FirImplicitStringTypeRef(session, null).toIrType(session, declarationStorage)
+
     private fun ModuleDescriptor.findPackageFragmentForFile(file: FirFile): PackageFragmentDescriptor =
         getPackage(file.packageFqName).fragments.first()
 
@@ -1070,6 +1072,15 @@ internal class Fir2IrVisitor(
         }
     }
 
+    override fun visitStringConcatenationCall(stringConcatenationCall: FirStringConcatenationCall, data: Any?): IrElement {
+        return stringConcatenationCall.convertWithOffsets { startOffset, endOffset ->
+            IrStringConcatenationImpl(
+                startOffset, endOffset, stringType,
+                stringConcatenationCall.arguments.map { it.toIrExpression() }
+            )
+        }
+    }
+
     override fun visitTypeOperatorCall(typeOperatorCall: FirTypeOperatorCall, data: Any?): IrElement {
         return typeOperatorCall.convertWithOffsets { startOffset, endOffset ->
             val irTypeOperand = typeOperatorCall.conversionTypeRef.toIrType(session, declarationStorage)

compiler/fir/psi2fir/src/org/jetbrains/kotlin/fir/builder/ConversionUtils.kt

@@ -304,14 +304,13 @@ internal fun Array<KtStringTemplateEntry>.toInterpolatingCall(
         }
         result = when {
             result == null -> nextArgument
-            callCreated && result is FirFunctionCallImpl -> result.apply {
+            callCreated && result is FirStringConcatenationCallImpl -> result.apply {
                 arguments += nextArgument
             }
             else -> {
                 callCreated = true
-                FirFunctionCallImpl(session, base).apply {
+                FirStringConcatenationCallImpl(session, base).apply {
-                    calleeReference = FirSimpleNamedReference(session, base, OperatorNameConventions.PLUS)
+                    arguments += result!!
-                    explicitReceiver = result
                     arguments += nextArgument
                 }
             }

compiler/fir/psi2fir/testData/rawBuilder/expressions/for.txt

@@ -43,7 +43,7 @@ FILE: for.kt
             lval <destruct>: <implicit> = <iterator>#.next#()
             lval x: <implicit> = <destruct>#.component1()
             lval y: <implicit> = <destruct>#.component2()
-            println#(String(x = ).plus#(x#, String( y = ), y#))
+            println#(<strcat>(String(x = ), x#, String( y = ), y#))
         }
 
     }

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)
     }

compiler/testData/ir/irText/declarations/constValInitializers.fir.txt

@@ -59,8 +59,9 @@ FILE fqName:<root> fileName:/constValInitializers.kt
   PROPERTY name:STR4 visibility:public modality:FINAL [const,val]
     FIELD PROPERTY_BACKING_FIELD name:STR4 type:kotlin.String visibility:public [final,static]
       EXPRESSION_BODY
-        CALL 'public final fun plus (other: kotlin.Any?): kotlin.String declared in kotlin.String' type=kotlin.String origin=null
+        STRING_CONCATENATION type=kotlin.String
-          other: CALL 'public final fun <get-STR2> (): kotlin.String declared in <root>' type=kotlin.String origin=null
+          CALL 'public final fun <get-STR1> (): kotlin.String declared in <root>' type=kotlin.String origin=null
+          CALL 'public final fun <get-STR2> (): kotlin.String declared in <root>' type=kotlin.String origin=null
     FUN DEFAULT_PROPERTY_ACCESSOR name:<get-STR4> visibility:public modality:FINAL <> () returnType:kotlin.String
       correspondingProperty: PROPERTY name:STR4 visibility:public modality:FINAL [const,val]
       BLOCK_BODY

compiler/testData/ir/irText/expressions/kt28006.fir.txt

@@ -38,7 +38,8 @@ FILE fqName:<root> fileName:/kt28006.kt
   PROPERTY name:testConst3 visibility:public modality:FINAL [const,val]
     FIELD PROPERTY_BACKING_FIELD name:testConst3 type:kotlin.String visibility:public [final,static]
       EXPRESSION_BODY
-        ERROR_CALL 'Cannot bind 2 arguments to plus call with 1 parameters' type=kotlin.String
+        STRING_CONCATENATION type=kotlin.String
+          CONST String type=kotlin.String value="\uD83E"
           CONST String type=kotlin.String value="\uDD17"
           CALL 'public final fun <get-testConst2> (): kotlin.String declared in <root>' type=kotlin.String origin=null
     FUN DEFAULT_PROPERTY_ACCESSOR name:<get-testConst3> visibility:public modality:FINAL <> () returnType:kotlin.String
@@ -49,8 +50,9 @@ FILE fqName:<root> fileName:/kt28006.kt
   PROPERTY name:testConst4 visibility:public modality:FINAL [const,val]
     FIELD PROPERTY_BACKING_FIELD name:testConst4 type:kotlin.String visibility:public [final,static]
       EXPRESSION_BODY
-        CALL 'public final fun plus (other: kotlin.Any?): kotlin.String declared in kotlin.String' type=kotlin.String origin=null
+        STRING_CONCATENATION type=kotlin.String
-          other: CALL 'public final fun <get-testConst2> (): kotlin.String declared in <root>' type=kotlin.String origin=null
+          CALL 'public final fun <get-testConst2> (): kotlin.String declared in <root>' type=kotlin.String origin=null
+          CALL 'public final fun <get-testConst2> (): kotlin.String declared in <root>' type=kotlin.String origin=null
     FUN DEFAULT_PROPERTY_ACCESSOR name:<get-testConst4> visibility:public modality:FINAL <> () returnType:kotlin.String
       correspondingProperty: PROPERTY name:testConst4 visibility:public modality:FINAL [const,val]
       BLOCK_BODY
@@ -60,21 +62,24 @@ FILE fqName:<root> fileName:/kt28006.kt
     VALUE_PARAMETER name:x index:0 type:kotlin.Int
     BLOCK_BODY
       RETURN type=kotlin.Nothing from='public final fun test1 (x: kotlin.Int): kotlin.String declared in <root>'
-        ERROR_CALL 'Cannot bind 2 arguments to plus call with 1 parameters' type=kotlin.String
+        STRING_CONCATENATION type=kotlin.String
-          CONST String type=kotlin.String value="\uDD17"
-          GET_VAR 'x: kotlin.Int declared in <root>.test1' type=kotlin.Int origin=null
-  FUN name:test2 visibility:public modality:FINAL <> (x:kotlin.Int) returnType:IrErrorType
-    VALUE_PARAMETER name:x index:0 type:kotlin.Int
-    BLOCK_BODY
-      RETURN type=kotlin.Nothing from='public final fun test2 (x: kotlin.Int): IrErrorType declared in <root>'
-        ERROR_CALL 'Unresolved reference: <Ambiguity: plus, [kotlin/Int.plus, kotlin/Int.plus, kotlin/Int.plus, kotlin/Int.plus, kotlin/Int.plus, kotlin/Int.plus]>#' type=IrErrorType
           CONST String type=kotlin.String value="\uD83E"
           CONST String type=kotlin.String value="\uDD17"
-  FUN name:test3 visibility:public modality:FINAL <> (x:kotlin.Int) returnType:IrErrorType
+          GET_VAR 'x: kotlin.Int declared in <root>.test1' type=kotlin.Int origin=null
+  FUN name:test2 visibility:public modality:FINAL <> (x:kotlin.Int) returnType:kotlin.String
     VALUE_PARAMETER name:x index:0 type:kotlin.Int
     BLOCK_BODY
-      RETURN type=kotlin.Nothing from='public final fun test3 (x: kotlin.Int): IrErrorType declared in <root>'
+      RETURN type=kotlin.Nothing from='public final fun test2 (x: kotlin.Int): kotlin.String declared in <root>'
-        ERROR_CALL 'Unresolved reference: <Ambiguity: plus, [kotlin/Int.plus, kotlin/Int.plus, kotlin/Int.plus, kotlin/Int.plus, kotlin/Int.plus, kotlin/Int.plus]>#' type=IrErrorType
+        STRING_CONCATENATION type=kotlin.String
+          GET_VAR 'x: kotlin.Int declared in <root>.test2' type=kotlin.Int origin=null
+          CONST String type=kotlin.String value="\uD83E"
+          CONST String type=kotlin.String value="\uDD17"
+  FUN name:test3 visibility:public modality:FINAL <> (x:kotlin.Int) returnType:kotlin.String
+    VALUE_PARAMETER name:x index:0 type:kotlin.Int
+    BLOCK_BODY
+      RETURN type=kotlin.Nothing from='public final fun test3 (x: kotlin.Int): kotlin.String declared in <root>'
+        STRING_CONCATENATION type=kotlin.String
+          GET_VAR 'x: kotlin.Int declared in <root>.test3' type=kotlin.Int origin=null
           CONST String type=kotlin.String value="\uD83E"
           CONST String type=kotlin.String value="\uDD17"
           GET_VAR 'x: kotlin.Int declared in <root>.test3' type=kotlin.Int origin=null

compiler/testData/ir/irText/expressions/objectReferenceInFieldInitializer.fir.txt

@@ -19,8 +19,9 @@ FILE fqName:<root> fileName:/objectReferenceInFieldInitializer.kt
     PROPERTY name:b visibility:private modality:FINAL [val]
       FIELD PROPERTY_BACKING_FIELD name:b type:kotlin.String visibility:private [final]
         EXPRESSION_BODY
-          CALL 'public final fun plus (other: kotlin.Any?): kotlin.String declared in kotlin.String' type=kotlin.String origin=null
+          STRING_CONCATENATION type=kotlin.String
-            other: CALL 'private final fun <get-a> (): kotlin.String declared in <root>.A' type=kotlin.String origin=null
+            CONST String type=kotlin.String value="1234"
+            CALL 'private final fun <get-a> (): kotlin.String declared in <root>.A' type=kotlin.String origin=null
       FUN DEFAULT_PROPERTY_ACCESSOR name:<get-b> visibility:private modality:FINAL <> ($this:<root>.A) returnType:kotlin.String
         correspondingProperty: PROPERTY name:b visibility:private modality:FINAL [val]
         $this: VALUE_PARAMETER name:<this> type:<root>.A

compiler/testData/ir/irText/expressions/stringTemplates.fir.txt

@@ -60,7 +60,8 @@ FILE fqName:<root> fileName:/stringTemplates.kt
   PROPERTY name:test6 visibility:public modality:FINAL [val]
     FIELD PROPERTY_BACKING_FIELD name:test6 type:kotlin.String visibility:public [final,static]
       EXPRESSION_BODY
-        ERROR_CALL 'Cannot bind 2 arguments to plus call with 1 parameters' type=kotlin.String
+        STRING_CONCATENATION type=kotlin.String
+          CALL 'public final fun <get-test1> (): kotlin.String declared in <root>' type=kotlin.String origin=null
           CONST String type=kotlin.String value=" "
           CALL 'public final fun foo (): kotlin.String declared in <root>' type=kotlin.String origin=null
     FUN DEFAULT_PROPERTY_ACCESSOR name:<get-test6> visibility:public modality:FINAL <> () returnType:kotlin.String

compiler/testData/ir/irText/regressions/coercionInLoop.fir.txt

@@ -19,8 +19,9 @@ FILE fqName:<root> fileName:/coercionInLoop.kt
                     GET_VAR 'var i: kotlin.Int [var] declared in <root>.box' type=kotlin.Int origin=null
                   arg1: ERROR_CALL 'Unresolved reference: <Unresolved name: next>#' type=IrErrorType
               then: RETURN type=kotlin.Nothing from='public final fun box (): kotlin.String declared in <root>'
-                CALL 'public final fun plus (other: kotlin.Any?): kotlin.String declared in kotlin.String' type=kotlin.String origin=null
+                STRING_CONCATENATION type=kotlin.String
-                  other: GET_VAR 'var i: kotlin.Int [var] declared in <root>.box' type=kotlin.Int origin=null
+                  CONST String type=kotlin.String value="Fail "
+                  GET_VAR 'var i: kotlin.Int [var] declared in <root>.box' type=kotlin.Int origin=null
           VAR name:<unary> type:kotlin.Int [val]
             GET_VAR 'var i: kotlin.Int [var] declared in <root>.box' type=kotlin.Int origin=null
           ERROR_CALL 'Unresolved reference: R|<local>/i|' type=IrErrorType