From b8d03cf021d806a27dcb129b2008f3a62f9819b2 Mon Sep 17 00:00:00 2001
From: Tagir Valeev <tagir.valeev@jetbrains.com>
Date: Fri, 24 Oct 2025 15:26:15 +0200
Subject: [PATCH] [java-psi] PsiClassUtil#isThrowable: try traversing the
 hierarchy directly

We only need to traverse superclasses, not the interfaces, and may stop at any generic parameter. While there's no additional caching (like in super-class substitutor), it's still could be faster

GitOrigin-RevId: 8aec1d2f375d4c0f74e949b5b70d959a3330a432
---
 .../com/intellij/psi/util/PsiClassUtil.java   | 21 ++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/java/java-psi-api/src/com/intellij/psi/util/PsiClassUtil.java b/java/java-psi-api/src/com/intellij/psi/util/PsiClassUtil.java
index 9683201824d5..9963647b00b6 100644
--- a/java/java-psi-api/src/com/intellij/psi/util/PsiClassUtil.java
+++ b/java/java-psi-api/src/com/intellij/psi/util/PsiClassUtil.java
@@ -40,12 +40,19 @@ public final class PsiClassUtil {
    * @return true if class is {@code java.lang.Throwable} or legally inherits from it.
    */
   public static boolean isThrowable(@NotNull PsiClass psiClass) {
-    if (psiClass.isInterface()) return false;
-    if (psiClass.getTypeParameters().length > 0) return false; // Valid throwables are never generic
-    if (CommonClassNames.JAVA_LANG_THROWABLE.equals(psiClass.getQualifiedName())) return true;
-    PsiClass throwableClass =
-      JavaPsiFacade.getInstance(psiClass.getProject()).findClass(CommonClassNames.JAVA_LANG_THROWABLE, psiClass.getResolveScope());
-    if (throwableClass == null) return false;
-    return psiClass.isInheritor(throwableClass, true);
+    if (psiClass instanceof PsiAnonymousClass) {
+      psiClass = ((PsiAnonymousClass)psiClass).getBaseClassType().resolve();
+    }
+    while (true) {
+      if (psiClass == null) return false;
+      if (psiClass.isInterface()) return false;
+      if (psiClass.getTypeParameters().length > 0) return false; // Valid throwables are never generic
+      if (CommonClassNames.JAVA_LANG_THROWABLE.equals(psiClass.getQualifiedName())) return true;
+      PsiClassType[] types = psiClass.getExtendsListTypes();
+      if (types.length == 0) return false;
+      PsiClassType type = types[0];
+      if (type.getParameterCount() != 0) return false;
+      psiClass = type.resolve();
+    }
   }
 }
\ No newline at end of file