[PATCH] [Fernflower] prevent null to be cast as short/byte

src/org/jetbrains/java/decompiler/modules/decompiler/ExprProcessor.java

@@ -877,7 +877,7 @@ public class ExprProcessor implements CodeConstants {
     boolean quote = cast && exprent.getPrecedence() >= FunctionExprent.getPrecedence(FunctionExprent.FUNCTION_CAST);
 
     // cast instead to 'byte' / 'short' when int constant is used as a value for 'Byte' / 'Short'
-    if (castNarrowing && exprent.type == Exprent.EXPRENT_CONST) {
+    if (castNarrowing && exprent.type == Exprent.EXPRENT_CONST && !((ConstExprent) exprent).isNull()) {
       if (leftType.equals(VarType.VARTYPE_BYTE_OBJ)) {
         leftType = VarType.VARTYPE_BYTE;
       }

src/org/jetbrains/java/decompiler/modules/decompiler/exps/ConstExprent.java

@@ -247,6 +247,10 @@ public class ConstExprent extends Exprent {
     throw new RuntimeException("invalid constant type: " + constType);
   }
 
+  public boolean isNull() {
+    return CodeConstants.TYPE_NULL == constType.type;
+  }
+
   private static String convertStringToJava(String value, boolean ascii) {
     char[] arr = value.toCharArray();
     StringBuilder buffer = new StringBuilder(arr.length);

test/org/jetbrains/java/decompiler/SingleClassesTest.java

@@ -32,6 +32,7 @@ public class SingleClassesTest {
     fixture = null;
   }
 
+  @Test public void testPrimitiveNarrowing() { doTest("pkg/TestPrimitiveNarrowing"); }
   @Test public void testClassFields() { doTest("pkg/TestClassFields"); }
   @Test public void testInterfaceFields() { doTest("pkg/TestInterfaceFields"); }
   @Test public void testClassLambda() { doTest("pkg/TestClassLambda"); }

testData/results/TestPrimitiveNarrowing.dec

@@ -0,0 +1,64 @@
+package pkg;
+
+class TestPrimitiveNarrowing {
+   TestPrimitiveNarrowing(Short value) {
+   }// 6
+
+   static void invocations() {
+      withInteger((Integer)null);// 9
+      withShort((Short)null);// 10
+      withByte((Byte)null);// 11
+      new TestPrimitiveNarrowing((Short)null);// 12
+   }// 13
+
+   static void withByte(Byte defaultValue) {
+   }// 16
+
+   static void withInteger(Integer defaultValue) {
+   }// 19
+
+   static void withShort(Short defaultValue) {
+   }// 22
+}
+
+class 'pkg/TestPrimitiveNarrowing' {
+   method '<init> (Ljava/lang/Short;)V' {
+      4      4
+   }
+
+   method 'invocations ()V' {
+      0      7
+      1      7
+      4      8
+      5      8
+      8      9
+      9      9
+      10      10
+      15      11
+   }
+
+   method 'withByte (Ljava/lang/Byte;)V' {
+      0      14
+   }
+
+   method 'withInteger (Ljava/lang/Integer;)V' {
+      0      17
+   }
+
+   method 'withShort (Ljava/lang/Short;)V' {
+      0      20
+   }
+}
+
+Lines mapping:
+6 <-> 5
+9 <-> 8
+10 <-> 9
+11 <-> 10
+12 <-> 11
+13 <-> 12
+16 <-> 15
+19 <-> 18
+22 <-> 21
+Not mapped:
+5

testData/src/pkg/TestPrimitiveNarrowing.java

@@ -0,0 +1,24 @@
+package pkg;
+
+class TestPrimitiveNarrowing {
+
+  TestPrimitiveNarrowing(Short value) {
+  }
+
+  static void invocations() {
+    withInteger(null);
+    withShort(null);
+    withByte(null);
+    new TestPrimitiveNarrowing(null);
+  }
+
+  static void withByte(Byte defaultValue) {
+  }
+
+  static void withInteger(Integer defaultValue) {
+  }
+
+  static void withShort(Short defaultValue) {
+  }
+
+}