typetools · smillst · Mar 2, 2026 · Feb 24, 2026 · Feb 24, 2026 · Feb 24, 2026
diff --git a/checker-qual/src/main/java/org/checkerframework/checker/index/qual/EnsuresLTLengthOf.java b/checker-qual/src/main/java/org/checkerframework/checker/index/qual/EnsuresLTLengthOf.java
@@ -36,7 +36,7 @@
  *
  * <pre>{@code
  * public void useShiftIndex(@NonNegative int x) {
- *    // :: error: (argument)
+ *    // :: error: [argument]
  *    Arrays.fill(array, end, end + x, null);
  *    shiftIndex(x);
  *    Arrays.fill(array, end, end + x, null);

diff --git a/checker-qual/src/main/java/org/checkerframework/checker/units/qual/PolyUnit.java b/checker-qual/src/main/java/org/checkerframework/checker/units/qual/PolyUnit.java
@@ -29,7 +29,7 @@
  *   {@literal @}s int sec1 = 7 * UnitsTools.s;
  *   {@literal @}s int sec2 = triplePolyUnit(sec1);
  *
- *    // :: error: (assignment)
+ *    // :: error: [assignment]
  *   {@literal @}s int sec3 = triplePolyUnit(m1);
  *  }
  * </code></pre>

diff --git a/checker/build.gradle b/checker/build.gradle
@@ -465,7 +465,7 @@ tasks.register("ainferTestCheckerGenerateAjava", Test) {
   doLast {
     copyNonannotatedToAnnotatedDirectory("ainfer-testchecker")
 
-    // AinferTestCheckerAjavaValidationTest fails with "warning: (purity.methodref)", whenever
+    // AinferTestCheckerAjavaValidationTest fails with "warning: [purity.methodref]", whenever
     // there is a user-defined generic interface, and a variable of that type is assigned a
     // method reference.
     delete("tests/ainfer-testchecker/annotated/all-systems/java8/memberref/Issue946.java")

diff --git a/checker/jtreg/multiplecheckers/NullnessInterning1.out b/checker/jtreg/multiplecheckers/NullnessInterning1.out
@@ -1,4 +1,4 @@
-NullnessInterning.java:19:14: compiler.warn.proc.messager: (assignment)
-NullnessInterning.java:22:9: compiler.warn.proc.messager: (not.interned)
-NullnessInterning.java:22:14: compiler.warn.proc.messager: (not.interned)
+NullnessInterning.java:19:14: compiler.warn.proc.messager: [assignment]
+NullnessInterning.java:22:9: compiler.warn.proc.messager: [not.interned]
+NullnessInterning.java:22:14: compiler.warn.proc.messager: [not.interned]
 3 warnings
diff --git a/checker/jtreg/multiplecheckers/NullnessInterning2.out b/checker/jtreg/multiplecheckers/NullnessInterning2.out
@@ -1,3 +1,3 @@
-NullnessInterning.java:22:9: compiler.warn.proc.messager: (not.interned)
-NullnessInterning.java:22:14: compiler.warn.proc.messager: (not.interned)
+NullnessInterning.java:22:9: compiler.warn.proc.messager: [not.interned]
+NullnessInterning.java:22:14: compiler.warn.proc.messager: [not.interned]
 2 warnings
diff --git a/checker/jtreg/multiplecheckers/NullnessInterning3.out b/checker/jtreg/multiplecheckers/NullnessInterning3.out
@@ -1,2 +1,2 @@
-NullnessInterning.java:19:14: compiler.warn.proc.messager: (assignment)
+NullnessInterning.java:19:14: compiler.warn.proc.messager: [assignment]
 1 warning
diff --git a/checker/jtreg/nullness/issue1582/Foo.out b/checker/jtreg/nullness/issue1582/Foo.out
@@ -1,2 +1,2 @@
-Foo.java:15:18: compiler.err.proc.messager: (flowexpr.parse.error)
+Foo.java:15:18: compiler.err.proc.messager: [flowexpr.parse.error]
 1 error
diff --git a/checker/jtreg/nullness/issue1582/JavaExpressionParseError.out b/checker/jtreg/nullness/issue1582/JavaExpressionParseError.out
@@ -1,2 +1,2 @@
-JavaExpressionParseError.java:8:25: compiler.err.proc.messager: (flowexpr.parse.error.postcondition)
+JavaExpressionParseError.java:8:25: compiler.err.proc.messager: [flowexpr.parse.error.postcondition]
 1 error
diff --git a/checker/jtreg/nullness/issue1929/Issue1929.java b/checker/jtreg/nullness/issue1929/Issue1929.java
@@ -25,7 +25,7 @@ String[] fails2(Collection<String> c) {
 
   String[] fails3(Collection<String> c) {
     // We don't determine field types from initialization expressions.
-    // :: error: (return)
+    // :: error: [return]
     return c.toArray(EMPTY_STRING_ARRAY_3);
   }
 }
diff --git a/checker/jtreg/nullness/issue1958/NPE2Test.out b/checker/jtreg/nullness/issue1958/NPE2Test.out
@@ -1,5 +1,5 @@
-NPE2Test.java:3:39: compiler.err.proc.messager: (assignment)
-NPE2Test.java:8:42: compiler.err.proc.messager: (assignment)
-NPE2Test.java:13:42: compiler.err.proc.messager: (assignment)
-NPE2Test.java:16:40: compiler.err.proc.messager: (assignment)
+NPE2Test.java:3:39: compiler.err.proc.messager: [assignment]
+NPE2Test.java:8:42: compiler.err.proc.messager: [assignment]
+NPE2Test.java:13:42: compiler.err.proc.messager: [assignment]
+NPE2Test.java:16:40: compiler.err.proc.messager: [assignment]
 4 errors
diff --git a/checker/jtreg/nullness/issue2173/View.out b/checker/jtreg/nullness/issue2173/View.out
@@ -1,3 +1,3 @@
-- compiler.warn.proc.messager: (invalid.annotation.location.bytecode)
-- compiler.warn.proc.messager: (invalid.annotation.location.bytecode)
+- compiler.warn.proc.messager: [invalid.annotation.location.bytecode]
+- compiler.warn.proc.messager: [invalid.annotation.location.bytecode]
 2 warnings
diff --git a/checker/jtreg/nullness/issue820/AnonymousClass.out b/checker/jtreg/nullness/issue820/AnonymousClass.out
@@ -1,2 +1,2 @@
-AnonymousClass.java:4:27: compiler.err.proc.messager: (assignment)
+AnonymousClass.java:4:27: compiler.err.proc.messager: [assignment]
 1 error
diff --git a/checker/jtreg/nullness/issue820/Class1Class2-err.out b/checker/jtreg/nullness/issue820/Class1Class2-err.out
@@ -1,3 +1,3 @@
-Class1.java:29:22: compiler.err.proc.messager: (contracts.postcondition)
-Class2.java:15:20: compiler.err.proc.messager: (contracts.precondition)
+Class1.java:29:22: compiler.err.proc.messager: [contracts.postcondition]
+Class2.java:15:20: compiler.err.proc.messager: [contracts.precondition]
 2 errors
diff --git a/checker/jtreg/nullness/issue820/Class1MinClass2Min-err.out b/checker/jtreg/nullness/issue820/Class1MinClass2Min-err.out
@@ -1,2 +1,2 @@
-Class2Min.java:6:25: compiler.err.proc.messager: (assignment)
+Class2Min.java:6:25: compiler.err.proc.messager: [assignment]
 1 error
diff --git a/checker/jtreg/nullness/issue820/Class2Class1-err.out b/checker/jtreg/nullness/issue820/Class2Class1-err.out
@@ -1,3 +1,3 @@
-Class2.java:15:20: compiler.err.proc.messager: (contracts.precondition)
-Class1.java:29:22: compiler.err.proc.messager: (contracts.postcondition)
+Class2.java:15:20: compiler.err.proc.messager: [contracts.precondition]
+Class1.java:29:22: compiler.err.proc.messager: [contracts.postcondition]
 2 errors
diff --git a/checker/jtreg/nullness/issue820/ErrorAnonymousClass.out b/checker/jtreg/nullness/issue820/ErrorAnonymousClass.out
@@ -1,3 +1,3 @@
-Error.java:13:23: compiler.err.proc.messager: (assignment)
-AnonymousClass.java:4:27: compiler.err.proc.messager: (assignment)
+Error.java:13:23: compiler.err.proc.messager: [assignment]
+AnonymousClass.java:4:27: compiler.err.proc.messager: [assignment]
 2 errors
diff --git a/checker/jtreg/nullness/issue824/Class2.out b/checker/jtreg/nullness/issue824/Class2.out
@@ -1,9 +1,9 @@
-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)
+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/preciseErrorMsg/Class1.out b/checker/jtreg/nullness/preciseErrorMsg/Class1.out
@@ -1,2 +1,2 @@
-Class1.java:15:22: compiler.err.proc.messager: (flowexpr.parse.error)
+Class1.java:15:22: compiler.err.proc.messager: [flowexpr.parse.error]
 1 error
diff --git a/checker/jtreg/rawtypes/RawTypeFail.out b/checker/jtreg/rawtypes/RawTypeFail.out
@@ -1,6 +1,6 @@
 RawTypeFail.java:14:30: compiler.warn.prob.found.req: (compiler.misc.unchecked.assign), java.util.Map, java.util.Map<java.lang.String,java.lang.Object>
 RawTypeFail.java:15:31: compiler.warn.prob.found.req: (compiler.misc.unchecked.assign), java.util.HashMap, java.util.Map<java.lang.String,java.lang.Object>
-RawTypeFail.java:14:30: compiler.err.proc.messager: (assignment)
-RawTypeFail.java:15:31: compiler.err.proc.messager: (assignment)
+RawTypeFail.java:14:30: compiler.err.proc.messager: [assignment]
+RawTypeFail.java:15:31: compiler.err.proc.messager: [assignment]
 2 errors
 2 warnings
diff --git a/checker/jtreg/stubs/annotatedFor/WithStub.out b/checker/jtreg/stubs/annotatedFor/WithStub.out
@@ -1,3 +1,3 @@
-UseTest.java:18:18: compiler.err.proc.messager: (argument)
-UseTest.java:19:18: compiler.err.proc.messager: (argument)
+UseTest.java:18:18: compiler.err.proc.messager: [argument]
+UseTest.java:19:18: compiler.err.proc.messager: [argument]
 2 errors
diff --git a/checker/jtreg/stubs/annotatedFor/WithoutStub.out b/checker/jtreg/stubs/annotatedFor/WithoutStub.out
@@ -1,2 +1,2 @@
-UseTest.java:18:18: compiler.err.proc.messager: (argument)
+UseTest.java:18:18: compiler.err.proc.messager: [argument]
 1 error
diff --git a/checker/jtreg/stubs/annotatedFor/WithoutStubConservative.out b/checker/jtreg/stubs/annotatedFor/WithoutStubConservative.out
@@ -1,3 +1,3 @@
-UseTest.java:18:18: compiler.err.proc.messager: (argument)
-UseTest.java:20:37: compiler.err.proc.messager: (assignment)
+UseTest.java:18:18: compiler.err.proc.messager: [argument]
+UseTest.java:20:37: compiler.err.proc.messager: [assignment]
 2 errors
diff --git a/checker/jtreg/stubs/issue1456/WithStub.out b/checker/jtreg/stubs/issue1456/WithStub.out
@@ -1,2 +1,2 @@
-Main.java:26:13: compiler.err.proc.messager: (type.arguments.not.inferred)
+Main.java:26:13: compiler.err.proc.messager: [type.arguments.not.inferred]
 1 error
diff --git a/checker/jtreg/stubs/issue1456/WithoutStub.out b/checker/jtreg/stubs/issue1456/WithoutStub.out
@@ -1,8 +1,8 @@
-Main.java:16:30: compiler.err.proc.messager: (assignment)
-Main.java:17:42: compiler.err.proc.messager: (assignment)
-Main.java:18:31: compiler.err.proc.messager: (assignment)
-Main.java:19:31: compiler.err.proc.messager: (assignment)
-Main.java:20:29: compiler.err.proc.messager: (assignment)
-Main.java:21:43: compiler.err.proc.messager: (assignment)
-Main.java:22:46: compiler.err.proc.messager: (assignment)
+Main.java:16:30: compiler.err.proc.messager: [assignment]
+Main.java:17:42: compiler.err.proc.messager: [assignment]
+Main.java:18:31: compiler.err.proc.messager: [assignment]
+Main.java:19:31: compiler.err.proc.messager: [assignment]
+Main.java:20:29: compiler.err.proc.messager: [assignment]
+Main.java:21:43: compiler.err.proc.messager: [assignment]
+Main.java:22:46: compiler.err.proc.messager: [assignment]
 7 errors
diff --git a/checker/tests/README.md b/checker/tests/README.md
@@ -146,7 +146,7 @@ So the final test case would be:
 public class MyNullnessTest {
   void method() {
     Object nullable = null;
-    // :: error: (dereference.of.nullable)
+    // :: error: [dereference.of.nullable]
     nullable.toString();
   }
 }
@@ -163,7 +163,7 @@ You can indicate an expected warning (as opposed to error) by using
 "warning:" instead of "error:", as in
 
 ```java
-  // :: warning: (nulltest.redundant)
+  // :: warning: [nulltest.redundant]
   assert val != null;
 ```
 
@@ -173,7 +173,7 @@ a warning from the same line of code:
 
 ```java
   @Regex String s1 = null;
-  // :: error: (assignment) :: warning: (cast.unsafe)
+  // :: error: [assignment] :: warning: [cast.unsafe]
   @Regex(3) String s2 = (@Regex(2) String) s;
 ```
 
@@ -182,7 +182,7 @@ syntax, expected errors can be specified in a separate file using the .out
 file extension.  These files contain lines of the following format:
 
 ```output
-:19: error: (dereference.of.nullable)
+:19: error: [dereference.of.nullable]
 ```
 
 The number between the colons is the line number of the expected error

diff --git a/checker/tests/aggregate/NullnessAndRegex.java b/checker/tests/aggregate/NullnessAndRegex.java
@@ -4,17 +4,17 @@
 import org.checkerframework.checker.regex.qual.Regex;
 
 public class NullnessAndRegex {
-  // :: error: (assignment)
+  // :: error: [assignment]
   @Regex String s1 = "De(mo";
-  // :: error: (assignment)
+  // :: error: [assignment]
   Object f = null;
-  // :: error: (assignment)
+  // :: error: [assignment]
   @Regex String s2 = "De(mo";
 
   void localized(@Localized String s) {}
 
   void method() {
-    // :: error: (argument)
+    // :: error: [argument]
     localized("ldskjfldj"); // error
   }
 }
diff --git a/checker/tests/ainfer-index/non-annotated/DependentTypesViewpointAdaptationTest.java b/checker/tests/ainfer-index/non-annotated/DependentTypesViewpointAdaptationTest.java
@@ -59,13 +59,13 @@ public static void testThisInference(
 
   public void compute5(
       DependentTypesViewpointAdaptationTest this, DependentTypesViewpointAdaptationTest other) {
-    // :: warning: (assignment)
+    // :: warning: [assignment]
     @SameLen("this") DependentTypesViewpointAdaptationTest myOther = other;
   }
 
   // Same as compute5, but without an explicit this parameter.
   public void compute6(DependentTypesViewpointAdaptationTest other) {
-    // :: warning: (assignment)
+    // :: warning: [assignment]
     @SameLen("this") DependentTypesViewpointAdaptationTest myOther = other;
   }
 }
diff --git a/checker/tests/ainfer-nullness/non-annotated/MonotonicNonNullInferenceTest.java b/checker/tests/ainfer-nullness/non-annotated/MonotonicNonNullInferenceTest.java
@@ -2,27 +2,27 @@
 
 public class MonotonicNonNullInferenceTest {
 
-  // :: warning: (initialization.static.field.uninitialized)
+  // :: warning: [initialization.static.field.uninitialized]
   static String staticString1;
 
-  // :: warning: (assignment)
+  // :: warning: [assignment]
   static String staticString2 = null;
 
   static String staticString3;
 
   String instanceString1;
 
-  // :: warning: (assignment)
+  // :: warning: [assignment]
   String instanceString2 = null;
 
   String instanceString3;
 
   static {
-    // :: warning: (assignment)
+    // :: warning: [assignment]
     staticString3 = null;
   }
 
-  // :: warning: (initialization.fields.uninitialized)
+  // :: warning: [initialization.fields.uninitialized]
   MonotonicNonNullInferenceTest() {
     String instanceString3 = "hello";
   }

diff --git a/checker/tests/ainfer-nullness/non-annotated/NullTypeVarTest.java b/checker/tests/ainfer-nullness/non-annotated/NullTypeVarTest.java
@@ -8,7 +8,7 @@
 
 public class NullTypeVarTest {
 
-  // :: warning: (assignment)
+  // :: warning: [assignment]
   private String indentString = null;
 
   private List<String> indentStrings;

diff --git a/checker/tests/ainfer-nullness/non-annotated/TwoCtorGenericAbstract.java b/checker/tests/ainfer-nullness/non-annotated/TwoCtorGenericAbstract.java
@@ -6,7 +6,7 @@ public abstract class TwoCtorGenericAbstract<T extends Object> implements Set<T>
   protected T value;
 
   protected TwoCtorGenericAbstract() {
-    // :: warning: (assignment)
+    // :: warning: [assignment]
     this.value = null;
   }
 

diff --git a/checker/tests/ainfer-nullness/non-annotated/TypeVarPlumeUtil.java b/checker/tests/ainfer-nullness/non-annotated/TypeVarPlumeUtil.java
@@ -13,7 +13,7 @@ public V merge(@NonNull V value) {
   }
 
   public V mergeNullable(@Nullable V value) {
-    // :: warning: (return)
+    // :: warning: [return]
     return value;
   }
 }
diff --git a/checker/tests/ainfer-resourceleak/non-annotated/AddNotOwning.java b/checker/tests/ainfer-resourceleak/non-annotated/AddNotOwning.java
@@ -15,7 +15,7 @@ static class NonEmptyMustCallFinalField {
     final Foo f; // expect owning annotation for this field
 
     NonEmptyMustCallFinalField() {
-      // :: warning: (required.method.not.called)
+      // :: warning: [required.method.not.called]
       f = new Foo();
     }
 
@@ -32,12 +32,12 @@ Foo getFieldOnSomePath() {
     }
 
     void testNotOwningOnFinal() {
-      // :: warning: (required.method.not.called)
+      // :: warning: [required.method.not.called]
       Foo f = getField();
     }
 
     void testNotOwningOnGetFieldOnSomePath() {
-      // :: warning: (required.method.not.called)
+      // :: warning: [required.method.not.called]
       Foo f = getFieldOnSomePath();
     }
 
@@ -56,7 +56,7 @@ static class NonEmptyMustCallNonFinalField {
     @SuppressWarnings("missing.creates.mustcall.for")
     void initialyzeFoo() {
       f.a();
-      // :: warning: (required.method.not.called)
+      // :: warning: [required.method.not.called]
       f = new Foo();
     }
 
@@ -73,12 +73,12 @@ Foo getFieldOnSomePath() {
     }
 
     void testNotOwningOnNonFinal() {
-      // :: warning: (required.method.not.called)
+      // :: warning: [required.method.not.called]
       Foo f = getField();
     }
 
     void testNotOwningOnGetFieldOnSomePath() {
-      // :: warning: (required.method.not.called)
+      // :: warning: [required.method.not.called]
       Foo f = getFieldOnSomePath();
     }
 

diff --git a/checker/tests/ainfer-resourceleak/non-annotated/ClassWithTwoOwningFieldsTest.java b/checker/tests/ainfer-resourceleak/non-annotated/ClassWithTwoOwningFieldsTest.java
@@ -12,9 +12,9 @@ void a() {}
 
   @InheritableMustCall("close")
   private class ClassWithTwoOwningFields {
-    // :: warning: (required.method.not.called)
+    // :: warning: [required.method.not.called]
     final @Owning Foo foo1;
-    // :: warning: (required.method.not.called)
+    // :: warning: [required.method.not.called]
     final @Owning Foo foo2;
 
     public ClassWithTwoOwningFields(Foo f1, Foo f2) {
@@ -29,9 +29,9 @@ void close() {
   }
 
   void testTwoOwning() {
-    // :: warning: (required.method.not.called)
+    // :: warning: [required.method.not.called]
     Foo f1 = new Foo();
-    // :: warning: (required.method.not.called)
+    // :: warning: [required.method.not.called]
     Foo f2 = new Foo();
 
     ClassWithTwoOwningFields ff = new ClassWithTwoOwningFields(f1, f2);