FIR: introduce & use Throwable built-in type

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/FirHelpers.kt

@@ -320,8 +320,7 @@ fun Modality.toToken(): KtModifierKeywordToken = when (this) {
 val FirFunctionCall.isIterator
     get() = this.calleeReference.name.asString() == "<iterator>"
 
-internal val throwableClassLikeType =
+internal fun throwableClassLikeType(session: FirSession) = session.builtinTypes.throwableType.type
-    StandardClassIds.byName("Throwable").constructClassLikeType(emptyArray(), false)
 
-fun ConeKotlinType.isThrowable(session: FirSession) =
+fun ConeKotlinType.isSubtypeOfThrowable(session: FirSession) =
-    throwableClassLikeType.isSupertypeOf(session.typeCheckerContext, this.fullyExpandedType(session))
+    throwableClassLikeType(session).isSupertypeOf(session.typeCheckerContext, this.fullyExpandedType(session))

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirThrowableSubclassChecker.kt

@@ -6,7 +6,7 @@
 package org.jetbrains.kotlin.fir.analysis.checkers.declaration
 
 import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
-import org.jetbrains.kotlin.fir.analysis.checkers.isThrowable
+import org.jetbrains.kotlin.fir.analysis.checkers.isSubtypeOfThrowable
 import org.jetbrains.kotlin.fir.analysis.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
 import org.jetbrains.kotlin.fir.analysis.diagnostics.reportOn
@@ -33,7 +33,7 @@ object FirThrowableSubclassChecker : FirClassChecker() {
     }
 
     private fun FirClass<*>.hasThrowableSupertype(context: CheckerContext) =
-        superConeTypes.any { it !is ConeClassErrorType && it.isThrowable(context.session) }
+        superConeTypes.any { it !is ConeClassErrorType && it.isSubtypeOfThrowable(context.session) }
 
     private fun FirClass<*>.hasGenericOuterDeclaration(context: CheckerContext) =
         classId.isLocal && context.containingDeclarations.anyIsGeneric()

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirCatchParameterChecker.kt

@@ -6,7 +6,7 @@
 package org.jetbrains.kotlin.fir.analysis.checkers.expression
 
 import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
-import org.jetbrains.kotlin.fir.analysis.checkers.isThrowable
+import org.jetbrains.kotlin.fir.analysis.checkers.isSubtypeOfThrowable
 import org.jetbrains.kotlin.fir.analysis.checkers.throwableClassLikeType
 import org.jetbrains.kotlin.fir.analysis.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
@@ -38,8 +38,9 @@ object FirCatchParameterChecker : FirTryExpressionChecker() {
                 }
             }
 
-            if (!coneType.isThrowable(context.session)) {
+            val session = context.session
-                reporter.reportOn(catchParameter.source, FirErrors.TYPE_MISMATCH, throwableClassLikeType, coneType, context)
+            if (!coneType.isSubtypeOfThrowable(context.session)) {
+                reporter.reportOn(catchParameter.source, FirErrors.TYPE_MISMATCH, throwableClassLikeType(session), coneType, context)
             }
         }
     }

compiler/fir/cones/src/org/jetbrains/kotlin/fir/symbols/StandardClassIds.kt

@@ -41,6 +41,7 @@ object StandardClassIds {
     val ULong = Long.unsignedId()
 
     val String = "String".baseId()
+    val Throwable = "Throwable".baseId()
 
     val KProperty = "KProperty".reflectId()
     val KMutableProperty = "KMutableProperty".reflectId()

compiler/fir/tree/src/org/jetbrains/kotlin/fir/FirSession.kt

@@ -62,4 +62,5 @@ class BuiltinTypes {
     val nullableNothingType: FirImplicitBuiltinTypeRef = FirImplicitNullableNothingTypeRef(null)
     val charType: FirImplicitBuiltinTypeRef = FirImplicitCharTypeRef(null)
     val stringType: FirImplicitBuiltinTypeRef = FirImplicitStringTypeRef(null)
+    val throwableType: FirImplicitThrowableTypeRef = FirImplicitThrowableTypeRef(null)
 }

compiler/fir/tree/src/org/jetbrains/kotlin/fir/types/impl/FirImplicitBuiltinTypeRef.kt

@@ -109,6 +109,10 @@ class FirImplicitStringTypeRef(
     source: FirSourceElement?
 ) : FirImplicitBuiltinTypeRef(source, StandardClassIds.String)
 
+class FirImplicitThrowableTypeRef(
+    source: FirSourceElement?
+) : FirImplicitBuiltinTypeRef(source, StandardClassIds.Throwable)
+
 class FirImplicitKPropertyTypeRef(
     source: FirSourceElement?,
     typeArgument: ConeTypeProjection
@@ -177,6 +181,7 @@ fun FirImplicitBuiltinTypeRef.withFakeSource(kind: FirFakeSourceElementKind): Fi
         is FirImplicitNullableNothingTypeRef -> FirImplicitNullableNothingTypeRef(newSource)
         is FirImplicitCharTypeRef -> FirImplicitCharTypeRef(newSource)
         is FirImplicitStringTypeRef -> FirImplicitStringTypeRef(newSource)
+        is FirImplicitThrowableTypeRef -> FirImplicitThrowableTypeRef(newSource)
         is FirImplicitKPropertyTypeRef -> FirImplicitKPropertyTypeRef(
             newSource,
             typeArgument = type.typeArguments[0]