Fix isKotlinFunctionWithBigArity function

fixup! Fix `isKotlinFunctionWithBigArity` function

Fix `isKotlinFunctionWithBigArity` function

Previous implementation could return false positive results, e.g. for
class named `abacaba.kotlin.Function42`

^KT-61548: Fixed


Merge-request: KT-MR-11928
Merged-by: Vladislav Grechko <Vladislav.Grechko@jetbrains.com>

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirLightTreeBlackBoxCodegenTestGenerated.java

@@ -3326,6 +3326,12 @@ public class FirLightTreeBlackBoxCodegenTestGenerated extends AbstractFirLightTr
                 runTest("compiler/testData/codegen/box/builtinStubMethods/extendJavaClasses/hashSet.kt");
             }
 
+            @Test
+            @TestMetadata("kt61548.kt")
+            public void testKt61548() throws Exception {
+                runTest("compiler/testData/codegen/box/builtinStubMethods/extendJavaClasses/kt61548.kt");
+            }
+
             @Test
             @TestMetadata("mapEntry.kt")
             public void testMapEntry() throws Exception {

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirPsiBlackBoxCodegenTestGenerated.java

@@ -3326,6 +3326,12 @@ public class FirPsiBlackBoxCodegenTestGenerated extends AbstractFirPsiBlackBoxCo
                 runTest("compiler/testData/codegen/box/builtinStubMethods/extendJavaClasses/hashSet.kt");
             }
 
+            @Test
+            @TestMetadata("kt61548.kt")
+            public void testKt61548() throws Exception {
+                runTest("compiler/testData/codegen/box/builtinStubMethods/extendJavaClasses/kt61548.kt");
+            }
+
             @Test
             @TestMetadata("mapEntry.kt")
             public void testMapEntry() throws Exception {

compiler/testData/codegen/box/builtinStubMethods/extendJavaClasses/kt61548.kt

@@ -0,0 +1,27 @@
+// TARGET_BACKEND: JVM
+// IGNORE_LIGHT_ANALYSIS
+
+// FILE: Function42.java
+
+package abacaba.kotlin;
+
+public abstract class Function42 implements CharSequence {
+    @Override
+    public char charAt(int index) {
+        return 'a';
+    }
+}
+
+// FILE: box.kt
+
+package abacaba.kotlin
+
+abstract class KACharSequence : Function42() {
+    companion object {
+        const val x  = "OK"
+    }
+}
+
+fun box(): String {
+    return KACharSequence.x
+}

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxCodegenTestGenerated.java

@@ -3152,6 +3152,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 runTest("compiler/testData/codegen/box/builtinStubMethods/extendJavaClasses/hashSet.kt");
             }
 
+            @Test
+            @TestMetadata("kt61548.kt")
+            public void testKt61548() throws Exception {
+                runTest("compiler/testData/codegen/box/builtinStubMethods/extendJavaClasses/kt61548.kt");
+            }
+
             @Test
             @TestMetadata("mapEntry.kt")
             public void testMapEntry() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java

@@ -3326,6 +3326,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 runTest("compiler/testData/codegen/box/builtinStubMethods/extendJavaClasses/hashSet.kt");
             }
 
+            @Test
+            @TestMetadata("kt61548.kt")
+            public void testKt61548() throws Exception {
+                runTest("compiler/testData/codegen/box/builtinStubMethods/extendJavaClasses/kt61548.kt");
+            }
+
             @Test
             @TestMetadata("mapEntry.kt")
             public void testMapEntry() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenWithIrInlinerTestGenerated.java

@@ -3326,6 +3326,12 @@ public class IrBlackBoxCodegenWithIrInlinerTestGenerated extends AbstractIrBlack
                 runTest("compiler/testData/codegen/box/builtinStubMethods/extendJavaClasses/hashSet.kt");
             }
 
+            @Test
+            @TestMetadata("kt61548.kt")
+            public void testKt61548() throws Exception {
+                runTest("compiler/testData/codegen/box/builtinStubMethods/extendJavaClasses/kt61548.kt");
+            }
+
             @Test
             @TestMetadata("mapEntry.kt")
             public void testMapEntry() throws Exception {

compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -2916,6 +2916,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                 runTest("compiler/testData/codegen/box/builtinStubMethods/extendJavaClasses/hashSet.kt");
             }
 
+            @TestMetadata("kt61548.kt")
+            public void testKt61548() throws Exception {
+                runTest("compiler/testData/codegen/box/builtinStubMethods/extendJavaClasses/kt61548.kt");
+            }
+
             @TestMetadata("mapEntry.kt")
             public void testMapEntry() throws Exception {
                 runTest("compiler/testData/codegen/box/builtinStubMethods/extendJavaClasses/mapEntry.kt");

core/compiler.common.jvm/src/org/jetbrains/kotlin/builtins/jvm/JavaToKotlinClassMap.kt

@@ -150,12 +150,11 @@ object JavaToKotlinClassMap {
     }
 
     private fun isKotlinFunctionWithBigArity(kotlinFqName: FqNameUnsafe, prefix: String): Boolean {
-        val arityString = kotlinFqName.asString().substringAfter(prefix, "")
+        val fqNameAsString = kotlinFqName.asString()
-        if (arityString.isNotEmpty() && !arityString.startsWith('0')) {
+        if (!fqNameAsString.startsWith(prefix)) return false
-            val arity = arityString.toIntOrNull()
+        val arityString = fqNameAsString.substring(prefix.length)
-            return arity != null && arity >= BuiltInFunctionArity.BIG_ARITY
+        val arity = if (!arityString.startsWith('0')) arityString.toIntOrNull() else return false
-        }
+        return arity != null && arity >= BuiltInFunctionArity.BIG_ARITY
-        return false
     }
 
     private fun addMapping(platformMutabilityMapping: PlatformMutabilityMapping) {