FIR IDE: add severity to KtDiagnostic

idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/KotlinHighLevelDiagnosticHighlightingPass.kt

@@ -23,6 +23,7 @@ import com.intellij.openapi.editor.Editor
 import com.intellij.openapi.progress.ProgressIndicator
 import com.intellij.openapi.project.Project
 import com.intellij.psi.PsiFile
+import org.jetbrains.kotlin.diagnostics.Severity
 import org.jetbrains.kotlin.idea.frontend.api.analyze
 import org.jetbrains.kotlin.idea.frontend.api.diagnostics.KtDiagnostic
 import org.jetbrains.kotlin.idea.frontend.api.diagnostics.KtDiagnosticWithPsi
@@ -50,12 +51,18 @@ class KotlinHighLevelDiagnosticHighlightingPass(
     private fun addDiagnostic(diagnostic: KtDiagnosticWithPsi) {
         val fixes = service<KtQuickFixService>().getQuickFixesFor(diagnostic as KtFirDiagnostic)
         annotationHolder.runAnnotatorWithContext(diagnostic.psi) { element, annotator ->
-            annotationHolder.newAnnotation(HighlightSeverity.ERROR, diagnostic.getMessageToRender())
+            annotationHolder.newAnnotation(diagnostic.getHighlightSeverity(), diagnostic.getMessageToRender())
                 .addFixes(fixes)
                 .create()
         }
     }
 
+    private fun KtDiagnosticWithPsi.getHighlightSeverity() = when (severity) {
+        Severity.INFO -> HighlightSeverity.INFORMATION
+        Severity.ERROR -> HighlightSeverity.ERROR
+        Severity.WARNING -> HighlightSeverity.WARNING
+    }
+
 
     private fun AnnotationBuilder.addFixes(fixes: List<IntentionAction>) =
         fixes.fold(this, AnnotationBuilder::withFix)

idea/idea-frontend-api/src/org/jetbrains/kotlin/idea/frontend/api/diagnostics/KtDiagnostic.kt

@@ -7,11 +7,13 @@ package org.jetbrains.kotlin.idea.frontend.api.diagnostics
 
 import com.intellij.openapi.util.TextRange
 import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.diagnostics.Severity
 import org.jetbrains.kotlin.idea.frontend.api.ValidityToken
 import org.jetbrains.kotlin.idea.frontend.api.ValidityTokenOwner
 import kotlin.reflect.KClass
 
 interface KtDiagnostic : ValidityTokenOwner {
+    val severity: Severity
     val factoryName: String?
     val defaultMessage: String
 }
@@ -22,11 +24,13 @@ interface KtDiagnosticWithPsi : KtDiagnostic {
     val diagnosticClass: KClass<out KtDiagnosticWithPsi>
 }
 
-class KtSimpleDiagnostic(
+class KtNonBoundToPsiErrorDiagnostic(
     override val factoryName: String?,
     override val defaultMessage: String,
     override val token: ValidityToken,
-) : KtDiagnostic
+) : KtDiagnostic {
+    override val severity: Severity get() = Severity.ERROR
+}
 
 fun KtDiagnostic.getDefaultMessageWithFactoryName(): String =
     if (factoryName == null) defaultMessage

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/components/KtFirCallResolver.kt

@@ -6,7 +6,6 @@
 package org.jetbrains.kotlin.idea.frontend.api.fir.components
 
 import org.jetbrains.kotlin.builtins.StandardNames
-import org.jetbrains.kotlin.fir.analysis.diagnostics.toFirDiagnostic
 import org.jetbrains.kotlin.fir.expressions.FirFunctionCall
 import org.jetbrains.kotlin.fir.expressions.FirQualifiedAccessExpression
 import org.jetbrains.kotlin.fir.expressions.FirSafeCallExpression
@@ -25,7 +24,7 @@ import org.jetbrains.kotlin.idea.fir.low.level.api.api.getOrBuildFirSafe
 import org.jetbrains.kotlin.idea.frontend.api.*
 import org.jetbrains.kotlin.idea.frontend.api.calls.*
 import org.jetbrains.kotlin.idea.frontend.api.components.KtCallResolver
-import org.jetbrains.kotlin.idea.frontend.api.diagnostics.KtSimpleDiagnostic
+import org.jetbrains.kotlin.idea.frontend.api.diagnostics.KtNonBoundToPsiErrorDiagnostic
 import org.jetbrains.kotlin.idea.frontend.api.fir.KtFirAnalysisSession
 import org.jetbrains.kotlin.idea.frontend.api.fir.buildSymbol
 import org.jetbrains.kotlin.idea.frontend.api.symbols.*
@@ -113,13 +112,13 @@ internal class KtFirCallResolver(
     private fun FirErrorNamedReference.createErrorCallTarget(): KtErrorCallTarget =
         KtErrorCallTarget(
             getCandidateSymbols().mapNotNull { it.fir.buildSymbol(firSymbolBuilder) as? KtFunctionLikeSymbol },
-            source?.let { diagnostic.asKtDiagnostic(it) } ?: KtSimpleDiagnostic(factoryName = null, diagnostic.reason, token)
+            source?.let { diagnostic.asKtDiagnostic(it) } ?: KtNonBoundToPsiErrorDiagnostic(factoryName = null, diagnostic.reason, token)
         )
 
     private fun FirErrorReferenceWithCandidate.createErrorCallTarget(): KtErrorCallTarget =
         KtErrorCallTarget(
             getCandidateSymbols().mapNotNull { it.fir.buildSymbol(firSymbolBuilder) as? KtFunctionLikeSymbol },
-            source?.let { diagnostic.asKtDiagnostic(it) } ?: KtSimpleDiagnostic(factoryName = null, diagnostic.reason, token)
+            source?.let { diagnostic.asKtDiagnostic(it) } ?: KtNonBoundToPsiErrorDiagnostic(factoryName = null, diagnostic.reason, token)
         )
 
     private fun FirResolvedNamedReference.getKtFunctionOrConstructorSymbol(): KtFunctionLikeSymbol? =

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

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.idea.frontend.api.fir.diagnostics
 
 import com.intellij.openapi.util.TextRange
 import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.diagnostics.Severity
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDefaultErrorMessages
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnostic
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderer
@@ -35,4 +36,7 @@ internal interface KtAbstractFirDiagnostic : KtDiagnosticWithPsi {
 
     override val psi: PsiElement
         get() = firDiagnostic.psiElement
+
+    override val severity: Severity
+        get() = firDiagnostic.severity
 }