[Analysis API] implement better rendering for chained KtSubstitutor

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/KtSymbolByFirBuilder.kt

@@ -44,6 +44,7 @@ import org.jetbrains.kotlin.fir.resolve.getSymbolByLookupTag
 import org.jetbrains.kotlin.fir.resolve.inference.ConeTypeParameterBasedTypeVariable
 import org.jetbrains.kotlin.fir.scopes.impl.originalConstructorIfTypeAlias
 import org.jetbrains.kotlin.fir.resolve.providers.symbolProvider
+import org.jetbrains.kotlin.fir.resolve.substitution.ChainedSubstitutor
 import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutor
 import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutorByMap
 import org.jetbrains.kotlin.fir.resolve.toSymbol
@@ -505,6 +506,7 @@ internal class KtSymbolByFirBuilder constructor(
             if (substitutor == ConeSubstitutor.Empty) return KtSubstitutor.Empty(token)
             return when (substitutor) {
                 is ConeSubstitutorByMap -> KtFirMapBackedSubstitutor(substitutor, this@KtSymbolByFirBuilder)
+                is ChainedSubstitutor -> KtFirChainedSubstitutor(substitutor, this@KtSymbolByFirBuilder)
                 else -> KtFirGenericSubstitutor(substitutor, this@KtSymbolByFirBuilder)
             }
         }

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/types/KtFirSubstitutor.kt

@@ -7,12 +7,14 @@ package org.jetbrains.kotlin.analysis.api.fir.types
 
 import org.jetbrains.kotlin.analysis.api.KtAnalysisApiInternals
 import org.jetbrains.kotlin.analysis.api.fir.KtSymbolByFirBuilder
+import org.jetbrains.kotlin.analysis.api.impl.base.KtChainedSubstitutor
 import org.jetbrains.kotlin.analysis.api.impl.base.KtMapBackedSubstitutor
 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.types.KtSubstitutor
 import org.jetbrains.kotlin.analysis.api.types.KtType
+import org.jetbrains.kotlin.fir.resolve.substitution.ChainedSubstitutor
 import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutor
 import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutorByMap
 
@@ -49,4 +51,20 @@ internal class KtFirMapBackedSubstitutor(
 
         return result
     }
+}
+
+@OptIn(KtAnalysisApiInternals::class)
+internal class KtFirChainedSubstitutor(
+    substitutor: ChainedSubstitutor,
+    builder: KtSymbolByFirBuilder,
+) : AbstractKtFirSubstitutor<ChainedSubstitutor>(substitutor, builder), KtChainedSubstitutor {
+    override val first
+        get(): KtSubstitutor {
+            return builder.typeBuilder.buildSubstitutor(substitutor.first)
+        }
+
+    override val second
+        get(): KtSubstitutor {
+            return builder.typeBuilder.buildSubstitutor(substitutor.second)
+        }
 }

analysis/analysis-api-impl-base/src/org/jetbrains/kotlin/analysis/api/impl/base/substitutorMarkers.kt

@@ -20,4 +20,16 @@ interface KtMapBackedSubstitutor : KtSubstitutor {
      * Substitution rules in a form of a `Map<KtTypeParameterSymbol, KtType>`
      */
     fun getAsMap(): Map<KtTypeParameterSymbol, KtType>
-}
+}
+
+
+/**
+ * A [KtSubstitutor] which substitution logic can be represented as subsequent invocation of two substitutors [first] and [second]
+ * This is an implementation detail,
+ * and Analysis API clients should not depend on the fact if some [KtSubstitutor] is [KtChainedSubstitutor] or not.
+ */
+@KtAnalysisApiInternals
+interface KtChainedSubstitutor : KtSubstitutor {
+    val first: KtSubstitutor
+    val second: KtSubstitutor
+}

analysis/analysis-api-impl-base/tests/org/jetbrains/kotlin/analysis/api/impl/base/test/cases/components/testUtils.kt

@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.analysis.api.KtAnalysisSession
 import org.jetbrains.kotlin.analysis.api.calls.KtCall
 import org.jetbrains.kotlin.analysis.api.calls.KtCallableMemberCall
 import org.jetbrains.kotlin.analysis.api.diagnostics.KtDiagnostic
+import org.jetbrains.kotlin.analysis.api.impl.base.KtChainedSubstitutor
 import org.jetbrains.kotlin.analysis.api.impl.base.KtMapBackedSubstitutor
 import org.jetbrains.kotlin.analysis.api.renderer.declarations.impl.KtDeclarationRendererForSource
 import org.jetbrains.kotlin.analysis.api.renderer.declarations.modifiers.renderers.KtRendererKeywordFilter
@@ -31,9 +32,10 @@ import kotlin.reflect.KVisibility
 import kotlin.reflect.full.memberProperties
 
 @OptIn(KtAnalysisApiInternals::class)
-internal fun KtAnalysisSession.stringRepresentation(any: Any): String = with(any) {
+internal fun KtAnalysisSession.stringRepresentation(any: Any?): String = with(any) {
     fun KtType.render() = asStringForDebugging().replace('/', '.')
     return when (this) {
+        null -> "null"
         is KtFunctionLikeSymbol -> buildString {
             append(
                 when (this@with) {
@@ -84,6 +86,7 @@ internal fun KtAnalysisSession.stringRepresentation(any: Any): String = with(any
                 .joinToString(prefix = "{", postfix = "}") { (k, v) -> stringRepresentation(k) + " = " + v.asStringForDebugging() }
             "<map substitutor: $mappingText>"
         }
+        is KtChainedSubstitutor -> "${stringRepresentation(first)} then ${stringRepresentation(second)}"
         is KtSubstitutor -> "<complex substitutor>"
         is KtDiagnostic -> "$severity<$factoryName: $defaultMessage>"
         is KtType -> render()

compiler/fir/providers/src/org/jetbrains/kotlin/fir/resolve/substitution/Substitutors.kt

@@ -206,7 +206,7 @@ fun substitutorByMap(substitution: Map<FirTypeParameterSymbol, ConeKotlinType>,
     return ConeSubstitutorByMap(substitution, useSiteSession)
 }
 
-data class ChainedSubstitutor(private val first: ConeSubstitutor, private val second: ConeSubstitutor) : ConeSubstitutor() {
+data class ChainedSubstitutor(val first: ConeSubstitutor, val second: ConeSubstitutor) : ConeSubstitutor() {
     override fun substituteOrNull(type: ConeKotlinType): ConeKotlinType? {
         first.substituteOrNull(type)?.let { return second.substituteOrSelf(it) }
         return second.substituteOrNull(type)