[Analysis API] Hide FIR-specific diagnostic details.

Change the public-facing KtFirDiagnostic to be an interface, not
a class, and change the internal implementations to be classes, not
interfaces. This allows hiding access to the KtPsiDiagnostic underlying
the AA diagnostic class.

analysis/analysis-api-fir/analysis-api-fir-generator/src/org/jetbrains/kotlin/analysis/api/fir/generator/rendererrs/KtDiagnosticClassImplementationRenderer.kt

@@ -32,17 +32,17 @@ object KtDiagnosticClassImplementationRenderer : AbstractDiagnosticsDataClassRen
         withIndent {
             printParameters(diagnostic, diagnosticList)
         }
-        print(") : KtFirDiagnostic.${diagnostic.className}(), KtAbstractFirDiagnostic<")
+        print(") : KtAbstractFirDiagnostic<")
         printTypeWithShortNames(diagnostic.original.psiType)
-        println(">")
+        println(">(firDiagnostic, token), KtFirDiagnostic.${diagnostic.className}")
     }
 
     private fun SmartPrinter.printParameters(diagnostic: HLDiagnostic, diagnosticList: HLDiagnosticList) {
         for (parameter in diagnostic.parameters) {
             printParameter(parameter, diagnosticList)
         }
-        println("override val firDiagnostic: KtPsiDiagnostic,")
-        println("override val token: KtLifetimeToken,")
+        println("firDiagnostic: KtPsiDiagnostic,")
+        println("token: KtLifetimeToken,")
     }
 
     private fun SmartPrinter.printParameter(parameter: HLDiagnosticParameter, diagnosticList: HLDiagnosticList) {

analysis/analysis-api-fir/analysis-api-fir-generator/src/org/jetbrains/kotlin/analysis/api/fir/generator/rendererrs/KtDiagnosticClassRenderer.kt

@@ -18,7 +18,7 @@ object KtDiagnosticClassRenderer : AbstractDiagnosticsDataClassRenderer() {
     }
 
     private fun SmartPrinter.printDiagnosticClasses(diagnosticList: HLDiagnosticList) {
-        inBracketsWithIndent("sealed class KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI>") {
+        inBracketsWithIndent("sealed interface KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI>") {
             for (diagnostic in diagnosticList.diagnostics) {
                 printDiagnosticClass(diagnostic, diagnosticList)
                 println()
@@ -27,9 +27,9 @@ object KtDiagnosticClassRenderer : AbstractDiagnosticsDataClassRenderer() {
     }
 
     private fun SmartPrinter.printDiagnosticClass(diagnostic: HLDiagnostic, diagnosticList: HLDiagnosticList) {
-        print("abstract class ${diagnostic.className} : KtFirDiagnostic<")
+        print("interface ${diagnostic.className} : KtFirDiagnostic<")
         printTypeWithShortNames(diagnostic.original.psiType)
-        print(">()")
+        print(">")
         inBracketsWithIndent {
             println("override val diagnosticClass get() = ${diagnostic.className}::class")
             printDiagnosticParameters(diagnostic, diagnosticList)
@@ -38,7 +38,7 @@ object KtDiagnosticClassRenderer : AbstractDiagnosticsDataClassRenderer() {
 
     private fun SmartPrinter.printDiagnosticParameters(diagnostic: HLDiagnostic, diagnosticList: HLDiagnosticList) {
         diagnostic.parameters.forEach { parameter ->
-            print("abstract val ${parameter.name}: ")
+            print("val ${parameter.name}: ")
             printTypeWithShortNames(parameter.type) { type ->
                 diagnosticList.containsClashingBySimpleNameType(type)
             }

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtAbstractFirDiagnostic.kt

@@ -9,14 +9,17 @@ import com.intellij.openapi.util.TextRange
 import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.analysis.api.lifetime.KtLifetimeOwner
 import org.jetbrains.kotlin.analysis.api.diagnostics.KtDiagnosticWithPsi
+import org.jetbrains.kotlin.analysis.api.lifetime.KtLifetimeToken
 import org.jetbrains.kotlin.analysis.api.lifetime.withValidityAssertion
 import org.jetbrains.kotlin.diagnostics.KtDiagnostic
 import org.jetbrains.kotlin.diagnostics.KtPsiDiagnostic
 import org.jetbrains.kotlin.diagnostics.Severity
 import org.jetbrains.kotlin.diagnostics.rendering.RootDiagnosticRendererFactory
 
-internal interface KtAbstractFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI>, KtLifetimeOwner {
-    val firDiagnostic: KtPsiDiagnostic
+internal abstract class KtAbstractFirDiagnostic<PSI : PsiElement>(
+    private val firDiagnostic: KtPsiDiagnostic,
+    override val token: KtLifetimeToken,
+) : KtDiagnosticWithPsi<PSI>, KtLifetimeOwner {
 
     override val factoryName: String
         get() = withValidityAssertion { firDiagnostic.factory.name }

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtCompilerPluginDiagnostic.kt

@@ -7,41 +7,41 @@ package org.jetbrains.kotlin.analysis.api.fir.diagnostics
 
 import com.intellij.psi.PsiElement
 
-abstract class KtCompilerPluginDiagnostic0 : KtFirDiagnostic<PsiElement>(), KtAbstractFirDiagnostic<PsiElement> {
-    final override val diagnosticClass
+interface KtCompilerPluginDiagnostic0 : KtFirDiagnostic<PsiElement> {
+    override val diagnosticClass
         get() = KtCompilerPluginDiagnostic0::class
 }
 
-abstract class KtCompilerPluginDiagnostic1 : KtFirDiagnostic<PsiElement>(), KtAbstractFirDiagnostic<PsiElement> {
-    abstract val parameter1: Any?
+interface KtCompilerPluginDiagnostic1 : KtFirDiagnostic<PsiElement> {
+    val parameter1: Any?
 
-    final override val diagnosticClass
+    override val diagnosticClass
         get() = KtCompilerPluginDiagnostic1::class
 }
 
-abstract class KtCompilerPluginDiagnostic2 : KtFirDiagnostic<PsiElement>(), KtAbstractFirDiagnostic<PsiElement> {
-    abstract val parameter1: Any?
-    abstract val parameter2: Any?
+interface KtCompilerPluginDiagnostic2 : KtFirDiagnostic<PsiElement> {
+    val parameter1: Any?
+    val parameter2: Any?
 
-    final override val diagnosticClass
+    override val diagnosticClass
         get() = KtCompilerPluginDiagnostic2::class
 }
 
-abstract class KtCompilerPluginDiagnostic3 : KtFirDiagnostic<PsiElement>(), KtAbstractFirDiagnostic<PsiElement> {
-    abstract val parameter1: Any?
-    abstract val parameter2: Any?
-    abstract val parameter3: Any?
+interface KtCompilerPluginDiagnostic3 : KtFirDiagnostic<PsiElement> {
+    val parameter1: Any?
+    val parameter2: Any?
+    val parameter3: Any?
 
-    final override val diagnosticClass
+    override val diagnosticClass
         get() = KtCompilerPluginDiagnostic3::class
 }
 
-abstract class KtCompilerPluginDiagnostic4 : KtFirDiagnostic<PsiElement>(), KtAbstractFirDiagnostic<PsiElement> {
-    abstract val parameter1: Any?
-    abstract val parameter2: Any?
-    abstract val parameter3: Any?
-    abstract val parameter4: Any?
+interface KtCompilerPluginDiagnostic4 : KtFirDiagnostic<PsiElement> {
+    val parameter1: Any?
+    val parameter2: Any?
+    val parameter3: Any?
+    val parameter4: Any?
 
-    final override val diagnosticClass
+    override val diagnosticClass
         get() = KtCompilerPluginDiagnostic4::class
 }

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtCompilerPluginDiagnosticImpl.kt

@@ -5,40 +5,41 @@
 
 package org.jetbrains.kotlin.analysis.api.fir.diagnostics
 
+import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.analysis.api.lifetime.KtLifetimeToken
 import org.jetbrains.kotlin.diagnostics.*
 
 internal class KtCompilerPluginDiagnostic0Impl(
-    override val firDiagnostic: KtPsiSimpleDiagnostic,
-    override val token: KtLifetimeToken
-) : KtCompilerPluginDiagnostic0()
+    firDiagnostic: KtPsiSimpleDiagnostic,
+    token: KtLifetimeToken
+) : KtAbstractFirDiagnostic<PsiElement>(firDiagnostic, token), KtCompilerPluginDiagnostic0
 
 internal class KtCompilerPluginDiagnostic1Impl(
-    override val firDiagnostic: KtPsiDiagnosticWithParameters1<*>,
-    override val token: KtLifetimeToken,
+    firDiagnostic: KtPsiDiagnosticWithParameters1<*>,
+    token: KtLifetimeToken,
     override val parameter1: Any?
-) : KtCompilerPluginDiagnostic1()
+) : KtAbstractFirDiagnostic<PsiElement>(firDiagnostic, token), KtCompilerPluginDiagnostic1
 
 internal class KtCompilerPluginDiagnostic2Impl(
-    override val firDiagnostic: KtPsiDiagnosticWithParameters2<*, *>,
-    override val token: KtLifetimeToken,
+    firDiagnostic: KtPsiDiagnosticWithParameters2<*, *>,
+    token: KtLifetimeToken,
     override val parameter1: Any?,
     override val parameter2: Any?
-) : KtCompilerPluginDiagnostic2()
+) : KtAbstractFirDiagnostic<PsiElement>(firDiagnostic, token), KtCompilerPluginDiagnostic2
 
 internal class KtCompilerPluginDiagnostic3Impl(
-    override val firDiagnostic: KtPsiDiagnosticWithParameters3<*, *, *>,
-    override val token: KtLifetimeToken,
+    firDiagnostic: KtPsiDiagnosticWithParameters3<*, *, *>,
+    token: KtLifetimeToken,
     override val parameter1: Any?,
     override val parameter2: Any?,
     override val parameter3: Any?
-) : KtCompilerPluginDiagnostic3()
+) : KtAbstractFirDiagnostic<PsiElement>(firDiagnostic, token), KtCompilerPluginDiagnostic3
 
 internal class KtCompilerPluginDiagnostic4Impl(
-    override val firDiagnostic: KtPsiDiagnosticWithParameters4<*, *, *, *>,
-    override val token: KtLifetimeToken,
+    firDiagnostic: KtPsiDiagnosticWithParameters4<*, *, *, *>,
+    token: KtLifetimeToken,
     override val parameter1: Any?,
     override val parameter2: Any?,
     override val parameter3: Any?,
     override val parameter4: Any?
-) : KtCompilerPluginDiagnostic4()
+) : KtAbstractFirDiagnostic<PsiElement>(firDiagnostic, token), KtCompilerPluginDiagnostic4