[Stubs] Fix stub inconsistency on unnamed setter parameters

If an unused setter parameter was replaced with an underscore ('_'),
it had a special name in the stub ('<anonymous parameter 0>'). The text
version of the stub inserted it as is, leading to an extra
'PsiErrorElement'.

^KTIJ-28194 Fixed

analysis/decompiled/decompiler-native/tests/org/jetbrains/kotlin/analysis/decompiler/konan/DecompiledKnmStubConsistencyFe10TestGenerated.java

@@ -311,4 +311,10 @@ public class DecompiledKnmStubConsistencyFe10TestGenerated extends AbstractDecom
     public void testTypes() throws Exception {
         runTest("analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/Types/");
     }
+
+    @Test
+    @TestMetadata("UnderscoreParameterName")
+    public void testUnderscoreParameterName() throws Exception {
+        runTest("analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/UnderscoreParameterName/");
+    }
 }

analysis/decompiled/decompiler-native/tests/org/jetbrains/kotlin/analysis/decompiler/konan/DecompiledKnmStubConsistencyK2TestGenerated.java

@@ -311,4 +311,10 @@ public class DecompiledKnmStubConsistencyK2TestGenerated extends AbstractDecompi
     public void testTypes() throws Exception {
         runTest("analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/Types/");
     }
+
+    @Test
+    @TestMetadata("UnderscoreParameterName")
+    public void testUnderscoreParameterName() throws Exception {
+        runTest("analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/UnderscoreParameterName/");
+    }
 }

analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/UnderscoreParameterName/UnderscoreParameterName.kt

@@ -0,0 +1,8 @@
+// FIR_IDENTICAL
+package test
+
+class UnderscoreParameterName {
+    var foo: String?
+        get() = null
+        set(_) {}
+}

analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/UnderscoreParameterName/UnderscoreParameterName.txt

@@ -0,0 +1,30 @@
+PsiJetFileStubImpl[package=test]
+  PACKAGE_DIRECTIVE
+    REFERENCE_EXPRESSION[referencedName=test]
+  IMPORT_LIST
+  CLASS[classId=test/UnderscoreParameterName, fqName=test.UnderscoreParameterName, isEnumEntry=false, isInterface=false, isLocal=false, isTopLevel=true, name=UnderscoreParameterName, superNames=[]]
+    MODIFIER_LIST[public final]
+    PRIMARY_CONSTRUCTOR[fqName=null, hasBody=false, isDelegatedCallToThis=false, isExtension=false, isTopLevel=false, name=UnderscoreParameterName]
+      MODIFIER_LIST[public]
+      VALUE_PARAMETER_LIST
+    CLASS_BODY
+      PROPERTY[fqName=test.UnderscoreParameterName.foo, hasDelegate=false, hasDelegateExpression=false, hasInitializer=false, hasReturnTypeRef=true, isExtension=false, isTopLevel=false, isVar=true, name=foo]
+        MODIFIER_LIST[public final]
+        TYPE_REFERENCE
+          NULLABLE_TYPE
+            USER_TYPE
+              USER_TYPE
+                REFERENCE_EXPRESSION[referencedName=kotlin]
+              REFERENCE_EXPRESSION[referencedName=String]
+        PROPERTY_ACCESSOR[hasBlockBody=true, hasBody=false, isGetter=true]
+          MODIFIER_LIST[public final]
+        PROPERTY_ACCESSOR[hasBlockBody=true, hasBody=true, isGetter=false]
+          MODIFIER_LIST[public final]
+          VALUE_PARAMETER_LIST
+            VALUE_PARAMETER[fqName=null, hasDefaultValue=false, hasValOrVar=false, isMutable=false, name=_]
+              TYPE_REFERENCE
+                NULLABLE_TYPE
+                  USER_TYPE
+                    USER_TYPE
+                      REFERENCE_EXPRESSION[referencedName=kotlin]
+                    REFERENCE_EXPRESSION[referencedName=String]

analysis/decompiled/decompiler-to-file-stubs/tests/org/jetbrains/kotlin/analysis/decompiler/stub/files/ClsStubBuilderK2CompilerTestGenerated.java

@@ -311,4 +311,10 @@ public class ClsStubBuilderK2CompilerTestGenerated extends AbstractClsStubBuilde
     public void testTypes() throws Exception {
         runTest("analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/Types/");
     }
+
+    @Test
+    @TestMetadata("UnderscoreParameterName")
+    public void testUnderscoreParameterName() throws Exception {
+        runTest("analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/UnderscoreParameterName/");
+    }
 }

analysis/decompiled/decompiler-to-file-stubs/tests/org/jetbrains/kotlin/analysis/decompiler/stub/files/ClsStubBuilderTestGenerated.java

@@ -311,4 +311,10 @@ public class ClsStubBuilderTestGenerated extends AbstractClsStubBuilderTest {
     public void testTypes() throws Exception {
         runTest("analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/Types/");
     }
+
+    @Test
+    @TestMetadata("UnderscoreParameterName")
+    public void testUnderscoreParameterName() throws Exception {
+        runTest("analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/UnderscoreParameterName/");
+    }
 }

analysis/decompiled/decompiler-to-psi/src/org/jetbrains/kotlin/analysis/decompiler/psi/text/buildDecompiledText.kt

@@ -7,10 +7,12 @@ package org.jetbrains.kotlin.analysis.decompiler.psi.text
 
 import org.jetbrains.kotlin.analysis.decompiler.stub.COMPILED_DEFAULT_INITIALIZER
 import org.jetbrains.kotlin.analysis.decompiler.stub.COMPILED_DEFAULT_PARAMETER_VALUE
+import org.jetbrains.kotlin.analysis.decompiler.stub.computeParameterName
 import org.jetbrains.kotlin.builtins.StandardNames
 import org.jetbrains.kotlin.contracts.description.ContractProviderKey
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.name.SpecialNames
 import org.jetbrains.kotlin.psi.psiUtil.quoteIfNeeded
 import org.jetbrains.kotlin.renderer.DescriptorRenderer
@@ -128,11 +130,8 @@ fun buildDecompiledText(
                             builder.append(descriptorRenderer.renderAnnotation(annotation))
                             builder.append(" ")
                         }
-                        val paramName = when (val name = parameterDescriptor.name) {
-                            SpecialNames.IMPLICIT_SET_PARAMETER -> StandardNames.DEFAULT_VALUE_PARAMETER
-                            else -> name
-                        }
-                        builder.append(paramName.asString()).append(": ")
+                        val parameterName = computeParameterName(parameterDescriptor.name)
+                        builder.append(parameterName.asString()).append(": ")
                             .append(descriptorRenderer.renderType(parameterDescriptor.type))
                         builder.append(")")
                         builder.append(" {").append(DECOMPILED_CODE_COMMENT).append(" }")

analysis/decompiled/decompiler-to-psi/tests/org/jetbrains/kotlin/analysis/decompiler/psi/ByDecompiledPsiStubBuilderK2CompilerTestGenerated.java

@@ -311,4 +311,10 @@ public class ByDecompiledPsiStubBuilderK2CompilerTestGenerated extends AbstractB
     public void testTypes() throws Exception {
         runTest("analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/Types/");
     }
+
+    @Test
+    @TestMetadata("UnderscoreParameterName")
+    public void testUnderscoreParameterName() throws Exception {
+        runTest("analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/UnderscoreParameterName/");
+    }
 }

analysis/decompiled/decompiler-to-psi/tests/org/jetbrains/kotlin/analysis/decompiler/psi/ByDecompiledPsiStubBuilderTestGenerated.java

@@ -311,4 +311,10 @@ public class ByDecompiledPsiStubBuilderTestGenerated extends AbstractByDecompile
     public void testTypes() throws Exception {
         runTest("analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/Types/");
     }
+
+    @Test
+    @TestMetadata("UnderscoreParameterName")
+    public void testUnderscoreParameterName() throws Exception {
+        runTest("analysis/decompiled/decompiler-to-file-stubs/testData/clsFileStubBuilder/UnderscoreParameterName/");
+    }
 }

analysis/decompiled/decompiler-to-stubs/src/org/jetbrains/kotlin/analysis/decompiler/stub/TypeClsStubBuilder.kt

@@ -330,14 +330,11 @@ class TypeClsStubBuilder(private val c: ClsStubBuilderContext) {
     ) {
         val parameterListStub = KotlinPlaceHolderStubImpl<KtParameterList>(parent, KtStubElementTypes.VALUE_PARAMETER_LIST)
         for ((index, valueParameterProto) in parameters.withIndex()) {
-            val paramName = when (val name = c.nameResolver.getName(valueParameterProto.name)) {
-                SpecialNames.IMPLICIT_SET_PARAMETER -> StandardNames.DEFAULT_VALUE_PARAMETER
-                else -> name
-            }
+            val parameterName = computeParameterName(c.nameResolver.getName(valueParameterProto.name))
             val hasDefaultValue = Flags.DECLARES_DEFAULT_VALUE.get(valueParameterProto.flags)
             val parameterStub = KotlinParameterStubImpl(
                 parameterListStub,
-                name = paramName.ref(),
+                name = parameterName.ref(),
                 fqName = null,
                 hasDefaultValue = hasDefaultValue,
                 hasValOrVar = false,

analysis/decompiled/decompiler-to-stubs/src/org/jetbrains/kotlin/analysis/decompiler/stub/clsStubBuilding.kt

@@ -19,6 +19,7 @@ import org.jetbrains.kotlin.metadata.jvm.deserialization.JvmProtoBufUtil
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.name.SpecialNames
 import org.jetbrains.kotlin.protobuf.MessageLite
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.stubs.KotlinUserTypeStub
@@ -249,3 +250,11 @@ val MessageLite.annotatedCallableKind: AnnotatedCallableKind
 fun Name.ref() = StringRef.fromString(this.asString())!!
 
 fun FqName.ref() = StringRef.fromString(this.asString())!!
+
+fun computeParameterName(name: Name): Name {
+    return when {
+        name == SpecialNames.IMPLICIT_SET_PARAMETER -> StandardNames.DEFAULT_VALUE_PARAMETER
+        SpecialNames.isAnonymousParameterName(name) -> Name.identifier("_")
+        else -> name
+    }
+}

compiler/frontend/src/org/jetbrains/kotlin/resolve/DescriptorResolver.java

@@ -42,6 +42,7 @@ import org.jetbrains.kotlin.diagnostics.Errors;
 import org.jetbrains.kotlin.incremental.components.NoLookupLocation;
 import org.jetbrains.kotlin.lexer.KtTokens;
 import org.jetbrains.kotlin.name.Name;
+import org.jetbrains.kotlin.name.SpecialNames;
 import org.jetbrains.kotlin.psi.*;
 import org.jetbrains.kotlin.psi.psiUtil.PsiUtilsKt;
 import org.jetbrains.kotlin.resolve.calls.components.InferenceSession;
@@ -366,7 +367,7 @@ public class DescriptorResolver {
             // of containing class where, it can not find a descriptor with special name.
             // Thus, to preserve behavior, we don't use a special name for val/var.
             parameterName = !valueParameter.hasValOrVar() && UnderscoreUtilKt.isSingleUnderscore(valueParameter)
-                            ? Name.special("<anonymous parameter " + index + ">")
+                            ? SpecialNames.anonymousParameterName(index)
                             : KtPsiUtil.safeName(valueParameter.getName());
         }
         else {

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/KotlinStubVersions.kt

@@ -17,7 +17,7 @@ object KotlinStubVersions {
     // Binary stub version should be increased if stub format (org.jetbrains.kotlin.psi.stubs.impl) is changed
     //      or changes are made to the core stub building code (org.jetbrains.kotlin.idea.decompiler.stubBuilder).
     // Increasing this version will lead to reindexing of all binary files that are potentially kotlin binaries (including all class files).
-    private const val BINARY_STUB_VERSION = 95
+    private const val BINARY_STUB_VERSION = 96
 
     // Classfile stub version should be increased if changes are made to classfile stub building subsystem (org.jetbrains.kotlin.idea.decompiler.classFile)
     // Increasing this version will lead to reindexing of all classfiles.

core/compiler.common/src/org/jetbrains/kotlin/name/SpecialNames.kt

@@ -88,6 +88,18 @@ object SpecialNames {
         return Name.special("<index_$idx>")
     }
 
+    private const val ANONYMOUS_PARAMETER_NAME_PREFIX = "anonymous parameter"
+
+    @JvmStatic
+    fun anonymousParameterName(index: Int): Name {
+        return Name.special("<$ANONYMOUS_PARAMETER_NAME_PREFIX $index>")
+    }
+
+    @JvmStatic
+    fun isAnonymousParameterName(name: Name): Boolean {
+        return name.isSpecial && name.asStringStripSpecialMarkers().startsWith(ANONYMOUS_PARAMETER_NAME_PREFIX)
+    }
+
     @JvmStatic
     fun safeIdentifier(name: Name?): Name {
         return if (name != null && !name.isSpecial) name else SAFE_IDENTIFIER_FOR_NO_NAME