Assignment context does not reject widening p.c. and boxing

biboudis · Mar 14, 2024 · d000889 · d000889
1 parent 481c866
commit d000889
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Showing 4 changed files with 43 additions and 6 deletions.
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java
@@ -2368,11 +2368,13 @@ public boolean isAssignable(Type t, Type s, Warner warn) {
                     return true;
                 break;
             case CLASS:
-                switch (unboxedType(s).getTag()) {
-                case BYTE:
-                case CHAR:
-                case SHORT:
-                    return isAssignable(t, unboxedType(s), warn);
+                Type unboxedType = unboxedType(s);
+                switch (unboxedType.getTag()) {
+                    case BYTE:
+                    case CHAR:
+                    case SHORT:
+                        return !t.getTag().isStrictSubRangeOf(unboxedType(s).getTag()) &&
+                               isAssignable(t, unboxedType(s), warn);
                 }
                 break;
             }

diff --git a/test/langtools/tools/javac/boxing/T6816548.java b/test/langtools/tools/javac/boxing/T6816548.java
@@ -53,7 +53,6 @@ public static void testShort() {
     public static void testByte() {
         final byte fb = 0;
         Byte b = fb;
-        Short s = fb;
         Character c = fb;
     }
 

diff --git a/test/langtools/tools/javac/patterns/AssignmentBug.java b/test/langtools/tools/javac/patterns/AssignmentBug.java
@@ -0,0 +1,31 @@
+/*
+ * @test /nodynamiccopyright/
+ * @summary Assignment context does not reject widening p.c. and boxing
+ * @compile/fail/ref=AssignmentBug.out -XDrawDiagnostics -XDshould-stop.at=FLOW AssignmentBug.java
+ */
+public class AssignmentBug {
+
+    void test() {
+        Integer t = (byte) 0;       // error, no widening p.c. from byte to int and boxing
+        Short s = (byte) 0;         // error, no widening p.c. from byte to short and boxing
+
+        Byte B1 = (char)0;          // ok, narrowing p.c. from char to byte and boxing when target is Byte
+        Byte B2 = (short)0;         // ok, narrowing p.c. from short to byte and boxing when target is Byte
+        Character C1 = (short)0;    // ok, narrowing p.c. from short to char and boxing when target is Character
+        Short S1 = (int)0;          // ok, narrowing p.c. from int to char and boxing to Short
+    }
+
+    void testWithSwitches() {
+        Integer i = 42;
+        var s1 = switch (i) {
+            case (byte)0 -> true;   // error
+            default -> false;
+        };
+
+        Short s = 42;
+        var s2 = switch (s) {
+            case (byte)0 -> true;   // error
+            default -> false;
+        };
+    }
+}
diff --git a/test/langtools/tools/javac/patterns/AssignmentBug.out b/test/langtools/tools/javac/patterns/AssignmentBug.out
@@ -0,0 +1,5 @@
+AssignmentBug.java:9:21: compiler.err.prob.found.req: (compiler.misc.inconvertible.types: byte, java.lang.Integer)
+AssignmentBug.java:10:19: compiler.err.prob.found.req: (compiler.misc.inconvertible.types: byte, java.lang.Short)
+AssignmentBug.java:21:18: compiler.err.prob.found.req: (compiler.misc.inconvertible.types: byte, java.lang.Integer)
+AssignmentBug.java:27:18: compiler.err.prob.found.req: (compiler.misc.inconvertible.types: byte, java.lang.Short)
+4 errors