Fixes patmat corner case that might produce a ClassCastException (#2405)

* Fixes patmat corner case that might produce a ClassCastException * src-gen changes
vavr-io · Apr 8, 2019 · 6cc64b4 · 6cc64b4
1 parent 71f55e0
commit 6cc64b4
Show file tree

Hide file tree

Showing 3 changed files with 38 additions and 4 deletions.
diff --git a/vavr/generator/Generator.scala b/vavr/generator/Generator.scala
@@ -1041,7 +1041,11 @@ def generateMainClasses(): Unit = {
 
                   @Override
                   public boolean isDefinedAt(T obj) {
-                      return predicate.test(obj);
+                      try {
+                          return predicate.test(obj);
+                      } catch (ClassCastException x) {
+                          return false;
+                      }
                   }
               };
           }
@@ -2983,7 +2987,7 @@ def generateTestClasses(): Unit = {
             public void shouldPassIssue2401() {
                 final $SeqType<String> empty = $StreamType.empty();
                 try {
-                    final String matched = Match(empty).of(
+                    Match(empty).of(
                             Case($$($ListType.empty()), ignored -> "list")
                     );
                     fail("expected MatchError");
@@ -2992,6 +2996,19 @@ def generateTestClasses(): Unit = {
                 }
             }
 
+            @$test
+            public void shouldCatchClassCastExceptionWhenPredicateHasDifferentType() {
+                try {
+                    final Object o = "";
+                    Match(o).of(
+                            Case($$((Integer i) -> true), "never")
+                    );
+                    fail("expected MatchError");
+                } catch (MatchError err) {
+                    // ok!
+                }
+            }
+
             // -- Match patterns
 
             static class ClzMatch {}

diff --git a/vavr/src-gen/main/java/io/vavr/API.java b/vavr/src-gen/main/java/io/vavr/API.java
@@ -5069,7 +5069,11 @@ public T apply(T obj) {
 
             @Override
             public boolean isDefinedAt(T obj) {
-                return predicate.test(obj);
+                try {
+                    return predicate.test(obj);
+                } catch (ClassCastException x) {
+                    return false;
+                }
             }
         };
     }

diff --git a/vavr/src-gen/test/java/io/vavr/APITest.java b/vavr/src-gen/test/java/io/vavr/APITest.java
@@ -1412,7 +1412,7 @@ public void shouldReturnNoneWhenApplyingCaseGivenPredicateAndValue() {
     public void shouldPassIssue2401() {
         final Seq<String> empty = Stream.empty();
         try {
-            final String matched = Match(empty).of(
+            Match(empty).of(
                     Case($(List.empty()), ignored -> "list")
             );
             fail("expected MatchError");
@@ -1421,6 +1421,19 @@ public void shouldPassIssue2401() {
         }
     }
 
+    @Test
+    public void shouldCatchClassCastExceptionWhenPredicateHasDifferentType() {
+        try {
+            final Object o = "";
+            Match(o).of(
+                    Case($((Integer i) -> true), "never")
+            );
+            fail("expected MatchError");
+        } catch (MatchError err) {
+            // ok!
+        }
+    }
+
     // -- Match patterns
 
     static class ClzMatch {}