FIR: fold String arguments inside string concatenation call

Related to KT-28006

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

@@ -839,10 +839,30 @@ class Fir2IrVisitor(
 
     override fun visitStringConcatenationCall(stringConcatenationCall: FirStringConcatenationCall, data: Any?): IrElement {
         return stringConcatenationCall.convertWithOffsets { startOffset, endOffset ->
-            IrStringConcatenationImpl(
+            val arguments = mutableListOf<IrExpression>()
-                startOffset, endOffset, irBuiltIns.stringType,
+            val sb = StringBuilder()
-                stringConcatenationCall.arguments.map { convertToIrExpression(it) }
+            var startArgumentOffset = -1
-            )
+            var endArgumentOffset = -1
+            for (firArgument in stringConcatenationCall.arguments) {
+                val argument = convertToIrExpression(firArgument)
+                if (argument is IrConst<*>) {
+                    if (sb.isEmpty()) {
+                        startArgumentOffset = argument.startOffset
+                    }
+                    sb.append(argument.value)
+                    endArgumentOffset = argument.endOffset
+                } else {
+                    if (sb.isNotEmpty()) {
+                        arguments += IrConstImpl.string(startArgumentOffset, endArgumentOffset, irBuiltIns.stringType, sb.toString())
+                        sb.clear()
+                    }
+                    arguments += argument
+                }
+            }
+            if (sb.isNotEmpty()) {
+                arguments += IrConstImpl.string(startArgumentOffset, endArgumentOffset, irBuiltIns.stringType, sb.toString())
+            }
+            IrStringConcatenationImpl(startOffset, endOffset, irBuiltIns.stringType, arguments)
         }
     }
 

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

@@ -1,36 +0,0 @@
-val test1: String
-  field = "\uD83E\uDD17"
-  get
-
-val test2: String
-  field = "\uD83E\uDD17\uD83E\uDD17"
-  get
-
-const val testConst1: String
-  field = "\uD83E\uDD17"
-  get
-
-const val testConst2: String
-  field = "\uD83E\uDD17\uD83E\uDD17"
-  get
-
-const val testConst3: String
-  field = "\uD83E\uDD17\uD83E\uDD17\uD83E\uDD17"
-  get
-
-const val testConst4: String
-  field = "\uD83E\uDD17\uD83E\uDD17\uD83E\uDD17\uD83E\uDD17"
-  get
-
-fun test1(x: Int): String {
-  return "\uD83E" + "\uDD17" + x
-}
-
-fun test2(x: Int): String {
-  return x + "\uD83E" + "\uDD17"
-}
-
-fun test3(x: Int): String {
-  return x + "\uD83E" + "\uDD17" + x
-}
-

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

@@ -1,80 +0,0 @@
-FILE fqName:<root> fileName:/kt28006.kt
-  PROPERTY name:test1 visibility:public modality:FINAL [val]
-    FIELD PROPERTY_BACKING_FIELD name:test1 type:kotlin.String visibility:private [final,static]
-      EXPRESSION_BODY
-        CONST String type=kotlin.String value="\uD83E\uDD17"
-    FUN DEFAULT_PROPERTY_ACCESSOR name:<get-test1> visibility:public modality:FINAL <> () returnType:kotlin.String
-      correspondingProperty: PROPERTY name:test1 visibility:public modality:FINAL [val]
-      BLOCK_BODY
-        RETURN type=kotlin.Nothing from='public final fun <get-test1> (): kotlin.String declared in <root>'
-          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:test1 type:kotlin.String visibility:private [final,static]' type=kotlin.String origin=null
-  PROPERTY name:test2 visibility:public modality:FINAL [val]
-    FIELD PROPERTY_BACKING_FIELD name:test2 type:kotlin.String visibility:private [final,static]
-      EXPRESSION_BODY
-        CONST String type=kotlin.String value="\uD83E\uDD17\uD83E\uDD17"
-    FUN DEFAULT_PROPERTY_ACCESSOR name:<get-test2> visibility:public modality:FINAL <> () returnType:kotlin.String
-      correspondingProperty: PROPERTY name:test2 visibility:public modality:FINAL [val]
-      BLOCK_BODY
-        RETURN type=kotlin.Nothing from='public final fun <get-test2> (): kotlin.String declared in <root>'
-          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:test2 type:kotlin.String visibility:private [final,static]' type=kotlin.String origin=null
-  PROPERTY name:testConst1 visibility:public modality:FINAL [const,val]
-    FIELD PROPERTY_BACKING_FIELD name:testConst1 type:kotlin.String visibility:public [final,static]
-      EXPRESSION_BODY
-        CONST String type=kotlin.String value="\uD83E\uDD17"
-    FUN DEFAULT_PROPERTY_ACCESSOR name:<get-testConst1> visibility:public modality:FINAL <> () returnType:kotlin.String
-      correspondingProperty: PROPERTY name:testConst1 visibility:public modality:FINAL [const,val]
-      BLOCK_BODY
-        RETURN type=kotlin.Nothing from='public final fun <get-testConst1> (): kotlin.String declared in <root>'
-          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:testConst1 type:kotlin.String visibility:public [final,static]' type=kotlin.String origin=null
-  PROPERTY name:testConst2 visibility:public modality:FINAL [const,val]
-    FIELD PROPERTY_BACKING_FIELD name:testConst2 type:kotlin.String visibility:public [final,static]
-      EXPRESSION_BODY
-        CONST String type=kotlin.String value="\uD83E\uDD17\uD83E\uDD17"
-    FUN DEFAULT_PROPERTY_ACCESSOR name:<get-testConst2> visibility:public modality:FINAL <> () returnType:kotlin.String
-      correspondingProperty: PROPERTY name:testConst2 visibility:public modality:FINAL [const,val]
-      BLOCK_BODY
-        RETURN type=kotlin.Nothing from='public final fun <get-testConst2> (): kotlin.String declared in <root>'
-          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:testConst2 type:kotlin.String visibility:public [final,static]' type=kotlin.String origin=null
-  PROPERTY name:testConst3 visibility:public modality:FINAL [const,val]
-    FIELD PROPERTY_BACKING_FIELD name:testConst3 type:kotlin.String visibility:public [final,static]
-      EXPRESSION_BODY
-        CONST String type=kotlin.String value="\uD83E\uDD17\uD83E\uDD17\uD83E\uDD17"
-    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
-        RETURN type=kotlin.Nothing from='public final fun <get-testConst3> (): kotlin.String declared in <root>'
-          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:testConst3 type:kotlin.String visibility:public [final,static]' type=kotlin.String origin=null
-  PROPERTY name:testConst4 visibility:public modality:FINAL [const,val]
-    FIELD PROPERTY_BACKING_FIELD name:testConst4 type:kotlin.String visibility:public [final,static]
-      EXPRESSION_BODY
-        CONST String type=kotlin.String value="\uD83E\uDD17\uD83E\uDD17\uD83E\uDD17\uD83E\uDD17"
-    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
-        RETURN type=kotlin.Nothing from='public final fun <get-testConst4> (): kotlin.String declared in <root>'
-          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:testConst4 type:kotlin.String visibility:public [final,static]' type=kotlin.String origin=null
-  FUN name:test1 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 test1 (x: kotlin.Int): kotlin.String declared in <root>'
-        STRING_CONCATENATION type=kotlin.String
-          CONST String type=kotlin.String value="\uD83E"
-          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:kotlin.String
-    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>'
-        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/kt28006.kt

@@ -1,3 +1,5 @@
+// FIR_IDENTICAL
+
 val test1 = "\uD83E\uDD17"
 val test2 = "\uD83E\uDD17\uD83E\uDD17"