[AA] KT-56617 Introduce PSI-based Java type parameter symbols

- Instead of extending the API with `typeParameterNames`, this commit
  creates a PSI-based Java type parameter symbol similarly to the
  PSI-based Java class symbol. Because completion requires only the type
  parameter name, this approach works fine, and without exposing an
  optimization via the API.

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/symbols/KtFirPsiJavaClassSymbol.kt

@@ -25,6 +25,7 @@ import org.jetbrains.kotlin.analysis.project.structure.getKtModule
 import org.jetbrains.kotlin.analysis.utils.classIdIfNonLocal
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.Visibility
+import org.jetbrains.kotlin.fir.declarations.FirTypeParameter
 import org.jetbrains.kotlin.fir.java.classKind
 import org.jetbrains.kotlin.fir.java.modality
 import org.jetbrains.kotlin.fir.symbols.impl.FirRegularClassSymbol
@@ -82,16 +83,21 @@ internal class KtFirPsiJavaClassSymbol(
             psi.containingClass?.let { KtFirPsiJavaClassSymbol(it, analysisSession) }
         }
 
-    override val typeParameterNames: List<Name> by cached {
+    override val typeParameters: List<KtTypeParameterSymbol> by cached {
-        // The parent Java class might contribute `FirOuterClassTypeParameterRef`s to the FIR class's type parameters (see
+        // The parent Java class might contribute type parameters to the Java type parameter stack, but for this KtSymbol, parent type 
-        // `FirJavaFacade.createFirJavaClass`), but since they are filtered out by `createRegularKtTypeParameters`, we do not need to
+        // parameters aren't relevant.
-        // include them in the list of type parameter names.
+        psi.typeParameters.mapIndexed { index, psiTypeParameter ->
-        javaClass.typeParameters.map { it.name }
+            KtFirPsiJavaTypeParameterSymbol(psiTypeParameter, analysisSession) {
+                // `psi.typeParameters` should align with the list of regular `FirTypeParameter`s, making the use of `index` valid.
+                val firTypeParameter = firSymbol.fir.typeParameters.filterIsInstance<FirTypeParameter>().getOrNull(index)
+                require(firTypeParameter != null) {
+                    "The FIR symbol's ${FirTypeParameter::class.simpleName}s should have an entry at $index."
+                }
+                firTypeParameter.symbol
+            }
+        }
     }
 
-    val hasTypeParameters: Boolean
-        get() = withValidityAssertion { psi.typeParameters.isNotEmpty() }
-
     val annotationSimpleNames: List<String?>
         get() = withValidityAssertion { psi.annotations.map { it.nameReferenceElement?.referenceName } }
 
@@ -122,11 +128,6 @@ internal class KtFirPsiJavaClassSymbol(
         firClassSymbol
     }
 
-    override val typeParameters: List<KtTypeParameterSymbol> by cached {
-        if (hasTypeParameters) firSymbol.createRegularKtTypeParameters(builder)
-        else emptyList()
-    }
-
     override val annotationsList: KtAnnotationsList by cached {
         if (hasAnnotations) KtFirAnnotationListForDeclaration.create(firSymbol, analysisSession.useSiteSession, token)
         else KtEmptyAnnotationsList(token)

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/symbols/KtFirPsiJavaTypeParameterSymbol.kt

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * 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.analysis.api.fir.symbols
+
+import com.intellij.psi.PsiTypeParameter
+import org.jetbrains.kotlin.analysis.api.fir.KtFirAnalysisSession
+import org.jetbrains.kotlin.analysis.api.fir.utils.cached
+import org.jetbrains.kotlin.analysis.api.lifetime.withValidityAssertion
+import org.jetbrains.kotlin.analysis.api.symbols.KtSymbolOrigin
+import org.jetbrains.kotlin.fir.symbols.impl.FirTypeParameterSymbol
+import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.name.SpecialNames
+import org.jetbrains.kotlin.types.Variance
+
+/**
+ * [KtFirPsiJavaTypeParameterSymbol] is a PSI-based type parameter symbol with a lazy [firSymbol]. Some properties such as [name] are
+ * computed based on the PSI. This is used by [KtFirPsiJavaClassSymbol] to avoid building its own FIR symbol when a list of type parameters
+ * is requested.
+ */
+internal class KtFirPsiJavaTypeParameterSymbol(
+    override val psi: PsiTypeParameter,
+    override val analysisSession: KtFirAnalysisSession,
+    private val computeFirSymbol: () -> FirTypeParameterSymbol,
+) : KtFirTypeParameterSymbolBase(), KtFirPsiSymbol<PsiTypeParameter, FirTypeParameterSymbol> {
+    override val name: Name = withValidityAssertion {
+        psi.name?.let { Name.identifier(it) } ?: SpecialNames.NO_NAME_PROVIDED
+    }
+
+    override val origin: KtSymbolOrigin
+        get() = withValidityAssertion { KtSymbolOrigin.JAVA }
+
+    override val variance: Variance
+        get() = withValidityAssertion { Variance.INVARIANT }
+
+    override val isReified: Boolean
+        get() = withValidityAssertion { false }
+
+    override val firSymbol: FirTypeParameterSymbol by cached {
+        computeFirSymbol()
+    }
+}

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/symbols/KtFirTypeParameterSymbol.kt

@@ -6,65 +6,24 @@
 package org.jetbrains.kotlin.analysis.api.fir.symbols
 
 import com.intellij.psi.PsiElement
-import org.jetbrains.kotlin.analysis.api.KtAnalysisSession
-import org.jetbrains.kotlin.analysis.api.annotations.KtAnnotationsList
 import org.jetbrains.kotlin.analysis.api.fir.KtFirAnalysisSession
-import org.jetbrains.kotlin.analysis.api.fir.annotations.KtFirAnnotationListForDeclaration
 import org.jetbrains.kotlin.analysis.api.fir.findPsi
-import org.jetbrains.kotlin.analysis.api.fir.symbols.pointers.KtFirTypeParameterSymbolPointer
-import org.jetbrains.kotlin.analysis.api.fir.symbols.pointers.requireOwnerPointer
 import org.jetbrains.kotlin.analysis.api.fir.utils.cached
 import org.jetbrains.kotlin.analysis.api.lifetime.KtLifetimeToken
 import org.jetbrains.kotlin.analysis.api.lifetime.withValidityAssertion
-import org.jetbrains.kotlin.analysis.api.symbols.KtTypeParameterSymbol
-import org.jetbrains.kotlin.analysis.api.symbols.pointers.KtPsiBasedSymbolPointer
-import org.jetbrains.kotlin.analysis.api.symbols.pointers.KtSymbolPointer
-import org.jetbrains.kotlin.analysis.api.types.KtType
-import org.jetbrains.kotlin.fir.analysis.checkers.typeParameterSymbols
 import org.jetbrains.kotlin.fir.symbols.impl.FirTypeParameterSymbol
-import org.jetbrains.kotlin.fir.types.isNullableAny
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.types.Variance
 
 internal class KtFirTypeParameterSymbol(
     override val firSymbol: FirTypeParameterSymbol,
     override val analysisSession: KtFirAnalysisSession,
-) : KtTypeParameterSymbol(), KtFirSymbol<FirTypeParameterSymbol> {
+) : KtFirTypeParameterSymbolBase() {
     override val token: KtLifetimeToken get() = builder.token
     override val psi: PsiElement? by cached { firSymbol.findPsi() }
 
-    override val annotationsList: KtAnnotationsList
-        get() = withValidityAssertion {
-            KtFirAnnotationListForDeclaration.create(firSymbol, analysisSession.useSiteSession, token)
-        }
-
     override val name: Name get() = withValidityAssertion { firSymbol.name }
 
-    override val upperBounds: List<KtType> by cached {
-        firSymbol.resolvedBounds.mapNotNull { type ->
-            if (type.isNullableAny) return@mapNotNull null
-            builder.typeBuilder.buildKtType(type)
-        }
-    }
-
     override val variance: Variance get() = withValidityAssertion { firSymbol.variance }
     override val isReified: Boolean get() = withValidityAssertion { firSymbol.isReified }
-
-    context(KtAnalysisSession)
-    override fun createPointer(): KtSymbolPointer<KtTypeParameterSymbol> = withValidityAssertion {
-        KtPsiBasedSymbolPointer.createForSymbolFromSource<KtTypeParameterSymbol>(this)?.let { return it }
-
-        val containingDeclarationSymbol = firSymbol.containingDeclarationSymbol
-        val typeParameters = containingDeclarationSymbol.typeParameterSymbols
-        requireNotNull(typeParameters) { "Containing declaration symbol: ${containingDeclarationSymbol::class.simpleName}" }
-
-        KtFirTypeParameterSymbolPointer(
-            ownerPointer = requireOwnerPointer(),
-            name = name,
-            index = typeParameters.indexOf(firSymbol),
-        )
-    }
-
-    override fun equals(other: Any?): Boolean = symbolEquals(other)
-    override fun hashCode(): Int = symbolHashCode()
 }

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/symbols/KtFirTypeParameterSymbolBase.kt

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * 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.analysis.api.fir.symbols
+
+import org.jetbrains.kotlin.analysis.api.KtAnalysisSession
+import org.jetbrains.kotlin.analysis.api.annotations.KtAnnotationsList
+import org.jetbrains.kotlin.analysis.api.fir.annotations.KtFirAnnotationListForDeclaration
+import org.jetbrains.kotlin.analysis.api.fir.symbols.pointers.KtFirTypeParameterSymbolPointer
+import org.jetbrains.kotlin.analysis.api.fir.symbols.pointers.requireOwnerPointer
+import org.jetbrains.kotlin.analysis.api.fir.utils.cached
+import org.jetbrains.kotlin.analysis.api.lifetime.withValidityAssertion
+import org.jetbrains.kotlin.analysis.api.symbols.KtTypeParameterSymbol
+import org.jetbrains.kotlin.analysis.api.symbols.pointers.KtPsiBasedSymbolPointer
+import org.jetbrains.kotlin.analysis.api.symbols.pointers.KtSymbolPointer
+import org.jetbrains.kotlin.analysis.api.types.KtType
+import org.jetbrains.kotlin.fir.symbols.impl.FirTypeParameterSymbol
+import org.jetbrains.kotlin.fir.types.isNullableAny
+import org.jetbrains.kotlin.fir.analysis.checkers.typeParameterSymbols
+
+/**
+ * [KtFirTypeParameterSymbolBase] provides shared implementations for [KtFirTypeParameterSymbol] and [KtFirPsiJavaTypeParameterSymbol].
+ */
+internal sealed class KtFirTypeParameterSymbolBase : KtTypeParameterSymbol(), KtFirSymbol<FirTypeParameterSymbol> {
+    override val annotationsList: KtAnnotationsList
+        get() = withValidityAssertion {
+            KtFirAnnotationListForDeclaration.create(firSymbol, analysisSession.useSiteSession, token)
+        }
+
+    override val upperBounds: List<KtType> by cached {
+        firSymbol.resolvedBounds.mapNotNull { type ->
+            if (type.isNullableAny) return@mapNotNull null
+            builder.typeBuilder.buildKtType(type)
+        }
+    }
+
+    context(KtAnalysisSession)
+    override fun createPointer(): KtSymbolPointer<KtTypeParameterSymbol> = withValidityAssertion {
+        KtPsiBasedSymbolPointer.createForSymbolFromSource<KtTypeParameterSymbol>(this)?.let { return it }
+
+        val containingDeclarationSymbol = firSymbol.containingDeclarationSymbol
+        val typeParameters = containingDeclarationSymbol.typeParameterSymbols
+        requireNotNull(typeParameters) { "Containing declaration symbol: ${containingDeclarationSymbol::class.simpleName}" }
+
+        KtFirTypeParameterSymbolPointer(
+            ownerPointer = requireOwnerPointer(),
+            name = name,
+            index = typeParameters.indexOf(firSymbol),
+        )
+    }
+
+    override fun equals(other: Any?): Boolean = symbolEquals(other)
+    override fun hashCode(): Int = symbolHashCode()
+}

analysis/analysis-api/src/org/jetbrains/kotlin/analysis/api/symbols/markers/markers.kt

@@ -5,7 +5,6 @@
 
 package org.jetbrains.kotlin.analysis.api.symbols.markers
 
-import org.jetbrains.kotlin.analysis.api.lifetime.withValidityAssertion
 import org.jetbrains.kotlin.analysis.api.symbols.KtSymbol
 import org.jetbrains.kotlin.analysis.api.symbols.KtTypeParameterSymbol
 import org.jetbrains.kotlin.name.Name
@@ -20,11 +19,4 @@ public interface KtNamedSymbol : KtPossiblyNamedSymbol {
 
 public interface KtSymbolWithTypeParameters : KtSymbol {
     public val typeParameters: List<KtTypeParameterSymbol>
-
-    /**
-     * The names of [typeParameters]. Using this property should be preferred if only the names of type parameters are needed, because some
-     * symbol implementations may avoid building the full list of type parameters.
-     */
-    public val typeParameterNames: List<Name>
-        get() = withValidityAssertion { typeParameters.map { it.name } }
 }