From 3083c0197855a49e3a59ac3e677e69db0e5db4bc Mon Sep 17 00:00:00 2001
Date: Fri, 22 Jan 2021 11:33:03 +0800
Subject: Backpot of JDK-8214345

Summary: infinite recursion while checking super class
LLT: langtools/test/tools/javac/generics/ClassBoundCheckingOverflow.java
Bug url: https://bugs.openjdk.java.net/browse/JDK-8214345
---
 .../classes/com/sun/tools/javac/comp/Check.java      |  7 +++++++
 .../javac/generics/ClassBoundCheckingOverflow.java   | 12 ++++++++++++
 .../javac/generics/ClassBoundCheckingOverflow.out    |  3 +++
 3 files changed, 22 insertions(+)
 create mode 100644 langtools/test/tools/javac/generics/ClassBoundCheckingOverflow.java
 create mode 100644 langtools/test/tools/javac/generics/ClassBoundCheckingOverflow.out

diff --git a/langtools/src/share/classes/com/sun/tools/javac/comp/Check.java b/langtools/src/share/classes/com/sun/tools/javac/comp/Check.java
index d5e9c47a4..68af43821 100644
--- a/langtools/src/share/classes/com/sun/tools/javac/comp/Check.java
+++ b/langtools/src/share/classes/com/sun/tools/javac/comp/Check.java
@@ -2617,6 +2617,10 @@ public class Check {
             if (type.isErroneous()) return;
             for (List<Type> l = types.interfaces(type); l.nonEmpty(); l = l.tail) {
                 Type it = l.head;
+                if (type.hasTag(CLASS) && !it.hasTag(CLASS)) {
+                    continue;
+                } // JLS 8.1.5
+
                 Type oldit = seensofar.put(it.tsym, it);
                 if (oldit != null) {
                     List<Type> oldparams = oldit.allparams();
@@ -2629,6 +2633,9 @@ public class Check {
                 checkClassBounds(pos, seensofar, it);
             }
             Type st = types.supertype(type);
+            if (type.hasTag(CLASS) && !st.hasTag(CLASS)) {
+                return;
+            } // JLS 8.1.4
             if (st != Type.noType) checkClassBounds(pos, seensofar, st);
         }
 
diff --git a/langtools/test/tools/javac/generics/ClassBoundCheckingOverflow.java b/langtools/test/tools/javac/generics/ClassBoundCheckingOverflow.java
new file mode 100644
index 000000000..1aeb7d71a
--- /dev/null
+++ b/langtools/test/tools/javac/generics/ClassBoundCheckingOverflow.java
@@ -0,0 +1,12 @@
+/*
+ * @test /nodynamiccopyright/
+ * @bug 8214345
+ * @summary infinite recursion while checking super class
+ *
+ * @compile/fail/ref=ClassBoundCheckingOverflow.out -XDrawDiagnostics ClassBoundCheckingOverflow.java
+ */
+
+public class ClassBoundCheckingOverflow {
+    abstract class InfiniteLoop1<E extends InfiniteLoop1<E>> extends E {}
+    abstract class InfiniteLoop2<E extends InfiniteLoop2<E>> implements E {}
+}
diff --git a/langtools/test/tools/javac/generics/ClassBoundCheckingOverflow.out b/langtools/test/tools/javac/generics/ClassBoundCheckingOverflow.out
new file mode 100644
index 000000000..bed6acfd7
--- /dev/null
+++ b/langtools/test/tools/javac/generics/ClassBoundCheckingOverflow.out
@@ -0,0 +1,3 @@
+ClassBoundCheckingOverflow.java:10:70: compiler.err.type.found.req: (compiler.misc.type.parameter: E), (compiler.misc.type.req.class)
+ClassBoundCheckingOverflow.java:11:73: compiler.err.type.found.req: (compiler.misc.type.parameter: E), (compiler.misc.type.req.class)
+2 errors
-- 
2.19.0