From 20559ab87479c279246dd3a1d6f6be06381ce709 Mon Sep 17 00:00:00 2001
From: Suvrat1629 <suvrat1629@gmail.com>
Date: Thu, 22 Jan 2026 12:55:16 +0530
Subject: [PATCH 1/7] add type parameter check for overriding functions

---
 checker/tests/nullness/A.class                | Bin 0 -> 634 bytes
 checker/tests/nullness/B.class                | Bin 0 -> 747 bytes
 checker/tests/nullness/Issue6741.class        | Bin 0 -> 1145 bytes
 checker/tests/nullness/Issue6816.class        | Bin 0 -> 1566 bytes
 checker/tests/nullness/Issue6864.class        | Bin 0 -> 806 bytes
 checker/tests/nullness/Issue6864.java         |  24 ++++++++
 .../common/basetype/BaseTypeVisitor.java      |  53 +++++++++++++++++-
 .../common/basetype/messages.properties       |   1 +
 8 files changed, 77 insertions(+), 1 deletion(-)
 create mode 100644 checker/tests/nullness/A.class
 create mode 100644 checker/tests/nullness/B.class
 create mode 100644 checker/tests/nullness/Issue6741.class
 create mode 100644 checker/tests/nullness/Issue6816.class
 create mode 100644 checker/tests/nullness/Issue6864.class
 create mode 100644 checker/tests/nullness/Issue6864.java

diff --git a/checker/tests/nullness/A.class b/checker/tests/nullness/A.class
new file mode 100644
index 0000000000000000000000000000000000000000..e397da41a1a44c0001560068ceec25a82ecadacb
GIT binary patch
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diff --git a/checker/tests/nullness/B.class b/checker/tests/nullness/B.class
new file mode 100644
index 0000000000000000000000000000000000000000..55bd935f05212a9d1467f2c58e952456d9bf659f
GIT binary patch
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HcmV?d00001

diff --git a/checker/tests/nullness/Issue6741.class b/checker/tests/nullness/Issue6741.class
new file mode 100644
index 0000000000000000000000000000000000000000..ff62f965d24ebfb20bc16ca50bbffe858bae700a
GIT binary patch
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HcmV?d00001

diff --git a/checker/tests/nullness/Issue6816.class b/checker/tests/nullness/Issue6816.class
new file mode 100644
index 0000000000000000000000000000000000000000..d1417cfcf26543b2fcacefac8e495208574fc4da
GIT binary patch
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literal 0
HcmV?d00001

diff --git a/checker/tests/nullness/Issue6864.class b/checker/tests/nullness/Issue6864.class
new file mode 100644
index 0000000000000000000000000000000000000000..4172c6ccd5a95513024b0cc6ac1c02049e37f0c7
GIT binary patch
literal 806
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literal 0
HcmV?d00001

diff --git a/checker/tests/nullness/Issue6864.java b/checker/tests/nullness/Issue6864.java
new file mode 100644
index 000000000000..6c04733976b3
--- /dev/null
+++ b/checker/tests/nullness/Issue6864.java
@@ -0,0 +1,24 @@
+import org.checkerframework.checker.nullness.qual.*;
+import java.util.*;
+
+class A {
+    <T extends List<Integer>> T m(T x) {
+        return x;
+    }
+}
+
+class B extends A {
+    <T extends List<@Nullable Integer>> T m(T x) {
+        x.add(null);
+        return x;
+    }
+}
+
+
+public class Issue6864 {
+    public static void main(String[] args) {
+        A x = new B();
+        List<Integer> y = new LinkedList<>();
+        x.m(y).get(0).toString();
+    }
+}
diff --git a/framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java b/framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java
index 896bcd3aac06..4378a3a93283 100644
--- a/framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java
+++ b/framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java
@@ -4142,7 +4142,13 @@ public boolean checkOverride() {
         return true;
       }
 
-      boolean result = checkReturn();
+      // First, ensure that method type parameter bounds are compatible. This must be
+      // checked before return/parameter checks because those checks may depend on
+      // the meaning of the type parameters.
+      boolean result = checkTypeParameters();
+
+      // Then check return type, parameters, receiver, and other properties.
+      result &= checkReturn();
       result &= checkParameters();
       if (isMethodReference) {
         result &= checkMemberReferenceReceivers();
@@ -4155,6 +4161,51 @@ public boolean checkOverride() {
       return result;
     }
 
+    /**
+     * Check that corresponding method type parameters have compatible bounds.
+     *
+     * @return true if type parameter bounds are compatible
+     */
+    private boolean checkTypeParameters() {
+      List<AnnotatedTypeVariable> subTypeVars = overrider.getTypeVariables();
+      List<AnnotatedTypeVariable> superTypeVars = overridden.getTypeVariables();
+
+      if (subTypeVars == null || superTypeVars == null) {
+        return true;
+      }
+      if (subTypeVars.size() != superTypeVars.size()) {
+        // Different number of type parameters is handled elsewhere (javac), so skip here.
+        return true;
+      }
+
+      boolean result = true;
+      for (int i = 0; i < subTypeVars.size(); i++) {
+        AnnotatedTypeVariable subVar = subTypeVars.get(i);
+        AnnotatedTypeVariable superVar = superTypeVars.get(i);
+
+        // Use the same containment test used for return type type variables: the
+        // overriding type variable's upper bound must be a subtype of the overridden's
+        // upper bound, and the overridden's lower bound must be a subtype of the
+        // overriding's lower bound.
+        boolean ok = testTypevarContainment(subVar, superVar);
+        if (!ok) {
+          FoundRequired pair = FoundRequired.of(subVar, superVar);
+          checker.reportError(
+              overriderTree,
+              "override.typeparam",
+              Integer.toString(i),
+              pair.found,
+              pair.required,
+              overriderType,
+              overrider,
+              overriddenType,
+              overridden);
+        }
+        result &= ok;
+      }
+      return result;
+    }
+
     /** Check that an override respects purity. */
     private void checkPurity() {
       String msgKey = isMethodReference ? "purity.methodref" : "purity.overriding";
diff --git a/framework/src/main/java/org/checkerframework/common/basetype/messages.properties b/framework/src/main/java/org/checkerframework/common/basetype/messages.properties
index adddb59542d5..a701697b4045 100644
--- a/framework/src/main/java/org/checkerframework/common/basetype/messages.properties
+++ b/framework/src/main/java/org/checkerframework/common/basetype/messages.properties
@@ -37,6 +37,7 @@ explicit.annotation.ignored=The qualifier %s is ignored in favor of %s. Either d
 override.return=Incompatible return type.%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%ncannot override method in %s%n  %s
 override.param=Incompatible parameter type for %s.%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%ncannot override method in %s%n  %s
 override.receiver=Incompatible receiver type%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%ncannot override method in %s%n  %s
+override.typeparam=Incompatible type parameter bounds for parameter %s.%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%ncannot override method in %s%n  %s
 methodref.return=Incompatible return type%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%nis not a valid method reference for method in %s%n  %s
 methodref.param=Incompatible parameter type for %s%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%nis not a valid method reference for method in %s%n  %s
 methodref.receiver=Incompatible receiver type%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%nis not a valid method reference for method in %s%n  %s

From 0918308574e0d1b7d43495c1d4a8f634b0fa97ce Mon Sep 17 00:00:00 2001
From: Suvrat1629 <suvrat1629@gmail.com>
Date: Fri, 30 Jan 2026 19:39:33 +0530
Subject: [PATCH 2/7] removing unnecessary files

Signed-off-by: Suvrat1629 <suvrat1629@gmail.com>
---
 checker/tests/nullness/A.class         | Bin 634 -> 0 bytes
 checker/tests/nullness/B.class         | Bin 747 -> 0 bytes
 checker/tests/nullness/Issue6741.class | Bin 1145 -> 0 bytes
 checker/tests/nullness/Issue6816.class | Bin 1566 -> 0 bytes
 checker/tests/nullness/Issue6864.class | Bin 806 -> 0 bytes
 checker/tests/nullness/Issue6864.java  |  27 ++++++++++++-------------
 6 files changed, 13 insertions(+), 14 deletions(-)
 delete mode 100644 checker/tests/nullness/A.class
 delete mode 100644 checker/tests/nullness/B.class
 delete mode 100644 checker/tests/nullness/Issue6741.class
 delete mode 100644 checker/tests/nullness/Issue6816.class
 delete mode 100644 checker/tests/nullness/Issue6864.class

diff --git a/checker/tests/nullness/A.class b/checker/tests/nullness/A.class
deleted file mode 100644
index e397da41a1a44c0001560068ceec25a82ecadacb..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

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diff --git a/checker/tests/nullness/B.class b/checker/tests/nullness/B.class
deleted file mode 100644
index 55bd935f05212a9d1467f2c58e952456d9bf659f..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

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diff --git a/checker/tests/nullness/Issue6741.class b/checker/tests/nullness/Issue6741.class
deleted file mode 100644
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GIT binary patch
literal 0
HcmV?d00001

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diff --git a/checker/tests/nullness/Issue6816.class b/checker/tests/nullness/Issue6816.class
deleted file mode 100644
index d1417cfcf26543b2fcacefac8e495208574fc4da..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

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zZxES*BxX{Wz^sXD$P8kRAscUpgNBOt!$FL&^C{%9VBo%qMLb}bIBZs_ww$K0io8{+
zaU$e(UiBT9{+_;8eD*y~7lAtZo^n;Qg?FjwIL)A)k2w}KOf2#nP<Kr{{ofZml-;p$
zE27HF+_u-HuRnoVP)fMVHupT?8F<8S`43P2wmk!nsWG~z(gD@+f_}mYI?VLdOE(>7
zV7Nr14856-OznYvpaId-Q!fK1j$sm42&hvR2&$vwpJBY-rzPy+_$~$$A93;%&i3Fd
zhIeuP)nOHVeggd%!vL~0x`kvqERh4!G!I|8<dmN4!PU+}I1gt;Lv2RPTEPhA=&T<0
zo}O`~L%6Qvm=1X?B=sQ-ODBai;gskivWO~-5+#+tLC+rCB#C<44EHE@8+ULQ4=IwO
L$P$+E1ZRH&tz(jn

diff --git a/checker/tests/nullness/Issue6864.class b/checker/tests/nullness/Issue6864.class
deleted file mode 100644
index 4172c6ccd5a95513024b0cc6ac1c02049e37f0c7..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

literal 806
zcmb7CU2oGc6g_Ucrp-dvm9}F*fiXVP4G{@V6QXERK^m$EMPj1}@szeEcugEg9H#NF
zc-aJ#5YPN5#C5u{!UGbK;_G|tbMA-lkDp(^0qA1gL=Jfa1q*X1GF11xkDe2F(s!N@
z_xMOL6dwvH)D}bDZVwEU7}z5dhGxw()H6b=MBunWPWadri85g#Z=!+)162!)s1d14
zf5>p%c4sMx>a_m`=21t(K-0n!E-+O7yibYvobqbey%Xk4x*Y=-85Yl~=t;$W9-COk
zWeY7_VJN9+N5w+=l)XJGF-1w@8bi64Bq`s#zq!FscpQy6!vYn^`)N4j@vb)v2q}b~
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zit#ZCm^)D#kNCFG9jN?n(_P(jtl%mQl>TyHdZcJwA+JT2k)2yR0{cuG8U$MPF;GJp
ztGGcFef5c+NV2QPFkT;_>>k4;Ydu@PbBJ^KFF2pWcPt;`(yKF}8VW?Iql5;kXp;C6
iZW3}2#by@c76=70qhsFIzTVi=gUru7LfeGru=Wd1U%l7>

diff --git a/checker/tests/nullness/Issue6864.java b/checker/tests/nullness/Issue6864.java
index 6c04733976b3..e1b9d9b59cc6 100644
--- a/checker/tests/nullness/Issue6864.java
+++ b/checker/tests/nullness/Issue6864.java
@@ -1,24 +1,23 @@
-import org.checkerframework.checker.nullness.qual.*;
 import java.util.*;
+import org.checkerframework.checker.nullness.qual.*;
 
 class A {
-    <T extends List<Integer>> T m(T x) {
-        return x;
-    }
+  <T extends List<Integer>> T m(T x) {
+    return x;
+  }
 }
 
 class B extends A {
-    <T extends List<@Nullable Integer>> T m(T x) {
-        x.add(null);
-        return x;
-    }
+  <T extends List<@Nullable Integer>> T m(T x) {
+    x.add(null);
+    return x;
+  }
 }
 
-
 public class Issue6864 {
-    public static void main(String[] args) {
-        A x = new B();
-        List<Integer> y = new LinkedList<>();
-        x.m(y).get(0).toString();
-    }
+  public static void main(String[] args) {
+    A x = new B();
+    List<Integer> y = new LinkedList<>();
+    x.m(y).get(0).toString();
+  }
 }

From 985d365346768ccebb0fc255e749870e6454d55d Mon Sep 17 00:00:00 2001
From: Suvrat1629 <suvrat1629@gmail.com>
Date: Fri, 30 Jan 2026 19:42:06 +0530
Subject: [PATCH 3/7] removing unnecessary comments

Signed-off-by: Suvrat1629 <suvrat1629@gmail.com>
---
 .../checkerframework/common/basetype/BaseTypeVisitor.java    | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java b/framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java
index 4378a3a93283..ef86424ad0cb 100644
--- a/framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java
+++ b/framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java
@@ -4174,7 +4174,6 @@ private boolean checkTypeParameters() {
         return true;
       }
       if (subTypeVars.size() != superTypeVars.size()) {
-        // Different number of type parameters is handled elsewhere (javac), so skip here.
         return true;
       }
 
@@ -4183,10 +4182,6 @@ private boolean checkTypeParameters() {
         AnnotatedTypeVariable subVar = subTypeVars.get(i);
         AnnotatedTypeVariable superVar = superTypeVars.get(i);
 
-        // Use the same containment test used for return type type variables: the
-        // overriding type variable's upper bound must be a subtype of the overridden's
-        // upper bound, and the overridden's lower bound must be a subtype of the
-        // overriding's lower bound.
         boolean ok = testTypevarContainment(subVar, superVar);
         if (!ok) {
           FoundRequired pair = FoundRequired.of(subVar, superVar);

From 1e18e3077c06fcf52d3d6b135ecafed6491d4087 Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Thu, 23 Apr 2026 08:06:26 -0700
Subject: [PATCH 4/7] Fix compilation error

---
 checker/tests/nullness/Issue6864.java | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/checker/tests/nullness/Issue6864.java b/checker/tests/nullness/Issue6864.java
index e1b9d9b59cc6..07174f57cc72 100644
--- a/checker/tests/nullness/Issue6864.java
+++ b/checker/tests/nullness/Issue6864.java
@@ -1,13 +1,14 @@
-import java.util.*;
-import org.checkerframework.checker.nullness.qual.*;
+import java.util.LinkedList;
+import java.util.List;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
-class A {
+class Issue6864_A {
   <T extends List<Integer>> T m(T x) {
     return x;
   }
 }
 
-class B extends A {
+class Issue6864_B extends Issue6864_A {
   <T extends List<@Nullable Integer>> T m(T x) {
     x.add(null);
     return x;
@@ -16,7 +17,7 @@ class B extends A {
 
 public class Issue6864 {
   public static void main(String[] args) {
-    A x = new B();
+    Issue6864_A x = new Issue6864_B();
     List<Integer> y = new LinkedList<>();
     x.m(y).get(0).toString();
   }

From c4391f294fe9234d8320b981f5b012db68e8f4ad Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Thu, 23 Apr 2026 08:08:25 -0700
Subject: [PATCH 5/7] Add contributor

---
 docs/manual/contributors.tex | 1 +
 1 file changed, 1 insertion(+)

diff --git a/docs/manual/contributors.tex b/docs/manual/contributors.tex
index fc5a6d8872f5..2eb88be2fa3b 100644
--- a/docs/manual/contributors.tex
+++ b/docs/manual/contributors.tex
@@ -141,6 +141,7 @@
 Steph Dietzel,
 Stephan Schroevers,
 Stuart Pernsteiner,
+Suvrat Acharya,
 Suzanne Millstein,
 Thomas Schweizer,
 Thomas Wei\ss schuh,

From ea6ec1ab92dd95181836b77621486d086f8085bf Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Thu, 23 Apr 2026 08:13:54 -0700
Subject: [PATCH 6/7] Fixes

---
 checker/tests/nullness/Issue6864.java                          | 1 +
 .../org/checkerframework/common/basetype/BaseTypeVisitor.java  | 3 ++-
 .../org/checkerframework/common/basetype/messages.properties   | 2 +-
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/checker/tests/nullness/Issue6864.java b/checker/tests/nullness/Issue6864.java
index 07174f57cc72..c3c9ddadaff6 100644
--- a/checker/tests/nullness/Issue6864.java
+++ b/checker/tests/nullness/Issue6864.java
@@ -9,6 +9,7 @@ <T extends List<Integer>> T m(T x) {
 }
 
 class Issue6864_B extends Issue6864_A {
+  // :: error: [override.typeparam]
   <T extends List<@Nullable Integer>> T m(T x) {
     x.add(null);
     return x;
diff --git a/framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java b/framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java
index 62d19545353a..8a1c6ef540e1 100644
--- a/framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java
+++ b/framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java
@@ -4172,6 +4172,7 @@ private boolean checkTypeParameters() {
         return true;
       }
       if (subTypeVars.size() != superTypeVars.size()) {
+        // Arity mismatch between the two methods' type parameters; Java will report an error.
         return true;
       }
 
@@ -4186,7 +4187,7 @@ private boolean checkTypeParameters() {
           checker.reportError(
               overriderTree,
               "override.typeparam",
-              Integer.toString(i),
+              subVar.getUnderlyingType().asElement().getSimpleName().toString(),
               pair.found,
               pair.required,
               overriderType,
diff --git a/framework/src/main/java/org/checkerframework/common/basetype/messages.properties b/framework/src/main/java/org/checkerframework/common/basetype/messages.properties
index a701697b4045..1d0cfe77459f 100644
--- a/framework/src/main/java/org/checkerframework/common/basetype/messages.properties
+++ b/framework/src/main/java/org/checkerframework/common/basetype/messages.properties
@@ -37,7 +37,7 @@ explicit.annotation.ignored=The qualifier %s is ignored in favor of %s. Either d
 override.return=Incompatible return type.%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%ncannot override method in %s%n  %s
 override.param=Incompatible parameter type for %s.%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%ncannot override method in %s%n  %s
 override.receiver=Incompatible receiver type%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%ncannot override method in %s%n  %s
-override.typeparam=Incompatible type parameter bounds for parameter %s.%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%ncannot override method in %s%n  %s
+override.typeparam=Incompatible type parameter bounds for type parameter %s.%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%ncannot override method in %s%n  %s
 methodref.return=Incompatible return type%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%nis not a valid method reference for method in %s%n  %s
 methodref.param=Incompatible parameter type for %s%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%nis not a valid method reference for method in %s%n  %s
 methodref.receiver=Incompatible receiver type%nfound   : %s%nrequired: %s%nConsequence: method in %s%n  %s%nis not a valid method reference for method in %s%n  %s

From 8c9585d83c3a84a2a6e3efd521b282c696a6b472 Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Thu, 23 Apr 2026 08:20:04 -0700
Subject: [PATCH 7/7] Rename files for uniqueness

---
 checker/jtreg/nullness/issue824/Class2.out             |  9 ---------
 .../issue824/{Class1.astub => Issue824_1.astub}        |  2 +-
 .../nullness/issue824/{Class2.java => Issue824_2.java} | 10 +++++-----
 checker/jtreg/nullness/issue824/Issue824_2.out         |  9 +++++++++
 .../issue824lib/{Class1.java => Issue824_1.java}       |  2 +-
 5 files changed, 16 insertions(+), 16 deletions(-)
 delete mode 100644 checker/jtreg/nullness/issue824/Class2.out
 rename checker/jtreg/nullness/issue824/{Class1.astub => Issue824_1.astub} (90%)
 rename checker/jtreg/nullness/issue824/{Class2.java => Issue824_2.java} (61%)
 create mode 100644 checker/jtreg/nullness/issue824/Issue824_2.out
 rename checker/jtreg/nullness/issue824lib/{Class1.java => Issue824_1.java} (89%)

diff --git a/checker/jtreg/nullness/issue824/Class2.out b/checker/jtreg/nullness/issue824/Class2.out
deleted file mode 100644
index 54703a0b76de..000000000000
--- a/checker/jtreg/nullness/issue824/Class2.out
+++ /dev/null
@@ -1,9 +0,0 @@
-Class2.java:14:39: compiler.err.proc.messager: [type.argument]
-Class2.java:15:20: compiler.err.proc.messager: [type.argument]
-Class2.java:15:45: compiler.err.proc.messager: [type.argument]
-Class2.java:16:27: compiler.err.proc.messager: [type.arguments.not.inferred]
-Class2.java:19:27: compiler.err.proc.messager: [type.arguments.not.inferred]
-Class2.java:20:26: compiler.err.proc.messager: [argument]
-Class2.java:24:14: compiler.err.proc.messager: [override.return]
-Class2.java:25:33: compiler.err.proc.messager: [type.arguments.not.inferred]
-8 errors
diff --git a/checker/jtreg/nullness/issue824/Class1.astub b/checker/jtreg/nullness/issue824/Issue824_1.astub
similarity index 90%
rename from checker/jtreg/nullness/issue824/Class1.astub
rename to checker/jtreg/nullness/issue824/Issue824_1.astub
index 58b898949ea0..f9e8497025a0 100644
--- a/checker/jtreg/nullness/issue824/Class1.astub
+++ b/checker/jtreg/nullness/issue824/Issue824_1.astub
@@ -1,7 +1,7 @@
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
- class Class1<Q extends @NonNull Object> {
+ class Issue824_1<Q extends @NonNull Object> {
     public <T extends @NonNull Object> T methodTypeParam(T t);
     public void classTypeParam(Q e);
 
diff --git a/checker/jtreg/nullness/issue824/Class2.java b/checker/jtreg/nullness/issue824/Issue824_2.java
similarity index 61%
rename from checker/jtreg/nullness/issue824/Class2.java
rename to checker/jtreg/nullness/issue824/Issue824_2.java
index 98790eb74ee4..27c88cb08162 100644
--- a/checker/jtreg/nullness/issue824/Class2.java
+++ b/checker/jtreg/nullness/issue824/Issue824_2.java
@@ -4,15 +4,15 @@
  * The defaults for type variable upper bounds with type Object changed since
  * the issue was filed.  So, this test case has been changed so that
  * annotations on type variable bounds in stub files is still tested.
- * @compile -Xlint:unchecked ../issue824lib/Class1.java
- * @compile/fail/ref=Class2.out -XDrawDiagnostics -Xlint:unchecked -processor org.checkerframework.checker.nullness.NullnessChecker -Anomsgtext Class2.java -Astubs=Class1.astub
- * @compile -Xlint:unchecked -processor org.checkerframework.checker.nullness.NullnessChecker -Anomsgtext Class2.java
+ * @compile -Xlint:unchecked ../issue824lib/Issue824_1.java
+ * @compile/fail/ref=Issue824_2.out -XDrawDiagnostics -Xlint:unchecked -processor org.checkerframework.checker.nullness.NullnessChecker -Anomsgtext Issue824_2.java -Astubs=Issue824_1.astub
+ * @compile -Xlint:unchecked -processor org.checkerframework.checker.nullness.NullnessChecker -Anomsgtext Issue824_2.java
  */
 
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-public class Class2<X> extends Class1<X> {
-  void call(Class1<@Nullable X> class1, Gen<@Nullable X> gen) {
+public class Issue824_2<X> extends Issue824_1<X> {
+  void call(Issue824_1<@Nullable X> class1, Gen<@Nullable X> gen) {
     class1.methodTypeParam(null);
     class1.classTypeParam(null);
 
diff --git a/checker/jtreg/nullness/issue824/Issue824_2.out b/checker/jtreg/nullness/issue824/Issue824_2.out
new file mode 100644
index 000000000000..0d34ce4aaeee
--- /dev/null
+++ b/checker/jtreg/nullness/issue824/Issue824_2.out
@@ -0,0 +1,9 @@
+Issue824_2.java:14:39: compiler.err.proc.messager: [type.argument]
+Issue824_2.java:15:20: compiler.err.proc.messager: [type.argument]
+Issue824_2.java:15:45: compiler.err.proc.messager: [type.argument]
+Issue824_2.java:16:27: compiler.err.proc.messager: [type.arguments.not.inferred]
+Issue824_2.java:19:27: compiler.err.proc.messager: [type.arguments.not.inferred]
+Issue824_2.java:20:26: compiler.err.proc.messager: [argument]
+Issue824_2.java:24:14: compiler.err.proc.messager: [override.return]
+Issue824_2.java:25:33: compiler.err.proc.messager: [type.arguments.not.inferred]
+8 errors
diff --git a/checker/jtreg/nullness/issue824lib/Class1.java b/checker/jtreg/nullness/issue824lib/Issue824_1.java
similarity index 89%
rename from checker/jtreg/nullness/issue824lib/Class1.java
rename to checker/jtreg/nullness/issue824lib/Issue824_1.java
index a358e8262bcc..04e87ccee363 100644
--- a/checker/jtreg/nullness/issue824lib/Class1.java
+++ b/checker/jtreg/nullness/issue824lib/Issue824_1.java
@@ -1,4 +1,4 @@
-public class Class1<Q> {
+public class Issue824_1<Q> {
   class Gen<S> {}
 
   public <T> T methodTypeParam(T t) {