Raw FIR: add work-around for deeply nested String interpolations

Controversial (but prevents total kotlin test failing)
Related to KT-29222

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

@@ -279,6 +279,7 @@ internal fun Array<KtStringTemplateEntry>.toInterpolatingCall(
     val sb = StringBuilder()
     var hasExpressions = false
     var result: FirExpression? = null
+    var callCreated = false
     for (entry in this) {
         val nextArgument = when (entry) {
             is KtLiteralStringTemplateEntry -> {
@@ -301,13 +302,19 @@ internal fun Array<KtStringTemplateEntry>.toInterpolatingCall(
                 )
             }
         }
-        result = when (result) {
+        result = when {
-            null -> nextArgument
+            result == null -> nextArgument
-            else -> FirFunctionCallImpl(session, base).apply {
+            callCreated && result is FirFunctionCallImpl -> result.apply {
-                calleeReference = FirSimpleNamedReference(session, base, OperatorNameConventions.PLUS)
-                explicitReceiver = result
                 arguments += nextArgument
             }
+            else -> {
+                callCreated = true
+                FirFunctionCallImpl(session, base).apply {
+                    calleeReference = FirSimpleNamedReference(session, base, OperatorNameConventions.PLUS)
+                    explicitReceiver = result
+                    arguments += nextArgument
+                }
+            }
         }
     }
     return if (hasExpressions) result!! else FirConstExpressionImpl(session, base, IrConstKind.String, sb.toString())

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

@@ -41,7 +41,7 @@ FILE: for.kt
             lval <destruct>: <implicit> = <iterator>#.next#()
             lval x: <implicit> = <destruct>#.component1()
             lval y: <implicit> = <destruct>#.component2()
-            println#(String(x = ).plus#(x#).plus#(String( y = )).plus#(y#))
+            println#(String(x = ).plus#(x#, String( y = ), y#))
         }
 
     }

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

@@ -38,8 +38,9 @@ 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
-        CALL 'public final fun plus (other: kotlin.Any?): kotlin.String declared in kotlin.String' type=kotlin.String origin=null
+        ERROR_CALL 'Cannot bind 2 arguments to plus call with 1 parameters' type=kotlin.String
-          other: CALL 'public final fun <get-testConst2> (): kotlin.String declared in <root>' type=kotlin.String origin=null
+          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
       correspondingProperty: PROPERTY name:testConst3 visibility:public modality:FINAL [const,val]
       BLOCK_BODY
@@ -59,17 +60,21 @@ 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>'
-        CALL 'public final fun plus (other: kotlin.Any?): kotlin.String declared in kotlin.String' type=kotlin.String origin=null
+        ERROR_CALL 'Cannot bind 2 arguments to plus call with 1 parameters' type=kotlin.String
-          other: GET_VAR 'x: kotlin.Int declared in <root>.test1' type=kotlin.Int origin=null
+          CONST String type=kotlin.String value="\uDD17"
-  FUN name:test2 visibility:public modality:FINAL <> (x:kotlin.Int) returnType:kotlin.String
+          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): kotlin.String declared in <root>'
+      RETURN type=kotlin.Nothing from='public final fun test2 (x: kotlin.Int): IrErrorType declared in <root>'
-        CALL 'public final fun plus (other: kotlin.Any?): kotlin.String declared in kotlin' type=kotlin.String origin=null
+        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
-          other: CONST String type=kotlin.String value="\uDD17"
+          CONST String type=kotlin.String value="\uD83E"
-  FUN name:test3 visibility:public modality:FINAL <> (x:kotlin.Int) returnType:kotlin.String
+          CONST String type=kotlin.String value="\uDD17"
+  FUN name:test3 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 test3 (x: kotlin.Int): kotlin.String declared in <root>'
+      RETURN type=kotlin.Nothing from='public final fun test3 (x: kotlin.Int): IrErrorType declared in <root>'
-        CALL 'public final fun plus (other: kotlin.Any?): kotlin.String declared in kotlin.String' type=kotlin.String origin=null
+        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
-          other: 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/stringTemplates.fir.txt

@@ -60,8 +60,9 @@ 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
-        CALL 'public final fun plus (other: kotlin.Any?): kotlin.String declared in kotlin.String' type=kotlin.String origin=null
+        ERROR_CALL 'Cannot bind 2 arguments to plus call with 1 parameters' type=kotlin.String
-          other: CALL 'public final fun foo (): 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
       correspondingProperty: PROPERTY name:test6 visibility:public modality:FINAL [val]
       BLOCK_BODY