Fix switch on enum false positive, add more tests

Author: jaskarth

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

@@ -399,8 +399,9 @@ private static boolean isEnumArray(Exprent exprent) {
         ClassesProcessor.ClassNode classNode = DecompilerContext.getClassProcessor().getMapRootClasses().get(field.getClassname());
 
         if (classNode == null || !"[I".equals(field.getDescriptor().descriptorString)) {
+          // TODO: tighten up this check to avoid false positives
           return field.getName().startsWith("$SwitchMap") || //This is non-standard but we don't have any more information so..
-            (index instanceof InvocationExprent && ((InvocationExprent) index).getName().equals("ordinal"));
+            (index instanceof InvocationExprent && ((InvocationExprent) index).getName().equals("ordinal")) && field.isStatic();
         }
 
         StructField stField;

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

@@ -714,6 +714,7 @@ private void registerDefault() {
     register(JAVA_8, "TestLVTReassignment");
     register(JAVA_8, "TestCatchVariable");
     register(JAVA_8, "TestExtraneousImports");
+    register(JAVA_17, "TestSwitchOnEnumFake");
   }
 
   private void registerEntireClassPath() {
@@ -829,6 +830,7 @@ private void registerPatternMatching() {
     // TODO: local variables aren't merged properly, bring out of nodebug when they are
     register(JAVA_16_NODEBUG, "TestPatternMatchingAssign");
     register(JAVA_16, "TestPatternMatchingLocalCapture");
+    register(JAVA_16, "TestPatternMatchingReturn");
 
     register(JAVA_17, "TestPatternMatching17");
     register(JAVA_17, "TestPatternMatching17Fake");

testData/results/pkg/TestPatternMatchingReturn.dec

@@ -0,0 +1,84 @@
+package pkg;
+
+public class TestPatternMatchingReturn {
+   public String getPattern(Object obj) {
+      if (obj instanceof String) {// 5
+         return (String)obj;// 6
+      } else {
+         System.out.println("filler");// 9
+         return null;// 11
+      }
+   }
+
+   public String get(Object obj) {
+      if (obj instanceof String) {// 15
+         return (String)obj;// 16
+      } else {
+         System.out.println("filler");// 19
+         return null;// 21
+      }
+   }
+}
+
+class 'pkg/TestPatternMatchingReturn' {
+   method 'getPattern (Ljava/lang/Object;)Ljava/lang/String;' {
+      0      4
+      2      4
+      3      4
+      4      4
+      5      4
+      6      4
+      7      4
+      8      4
+      9      5
+      a      5
+      b      5
+      c      5
+      f      5
+      10      7
+      11      7
+      12      7
+      13      7
+      14      7
+      15      7
+      16      7
+      17      7
+      18      8
+      19      8
+   }
+
+   method 'get (Ljava/lang/Object;)Ljava/lang/String;' {
+      0      13
+      1      13
+      2      13
+      3      13
+      4      13
+      5      13
+      6      13
+      7      14
+      8      14
+      9      14
+      a      14
+      b      14
+      c      16
+      d      16
+      e      16
+      f      16
+      10      16
+      11      16
+      12      16
+      13      16
+      14      17
+      15      17
+   }
+}
+
+Lines mapping:
+5 <-> 5
+6 <-> 6
+9 <-> 8
+11 <-> 9
+15 <-> 14
+16 <-> 15
+19 <-> 17
+21 <-> 18

testData/results/pkg/TestSwitchOnEnumFake.dec

@@ -0,0 +1,124 @@
+package pkg;
+
+public class TestSwitchOnEnumFake {
+   public byte[] values = new byte[TestSwitchOnEnumFake.Values.values().length];
+
+   public int test(TestSwitchOnEnumFake.Values v) {
+      int a = 0;// 14
+      int b = 0;// 15
+      byte var4;
+      byte var5;
+      switch (this.values[v.ordinal()]) {// 16
+         case 1:
+            var4 = 1;// 18
+            var5 = 2;// 19
+            break;// 20
+         case 2:
+            var4 = 2;// 22
+            var5 = 4;// 23
+            break;// 24
+         case 3:
+            var4 = 3;// 26
+            var5 = 6;// 27
+            break;// 28
+         default:
+            var4 = 1;// 30
+            var5 = 1;// 31
+      }
+
+      return var4 + var5;// 35
+   }
+
+   static enum Values {
+      A,
+      B,
+      C,
+      D;
+   }
+}
+
+class 'pkg/TestSwitchOnEnumFake' {
+   method 'test (Lpkg/TestSwitchOnEnumFake$Values;)I' {
+      0      6
+      1      6
+      2      7
+      3      7
+      4      10
+      5      10
+      6      10
+      7      10
+      8      10
+      9      10
+      a      10
+      b      10
+      c      10
+      d      10
+      e      10
+      f      10
+      10      10
+      11      10
+      12      10
+      13      10
+      14      10
+      15      10
+      16      10
+      17      10
+      18      10
+      19      10
+      1a      10
+      1b      10
+      1c      10
+      1d      10
+      1e      10
+      1f      10
+      20      10
+      21      10
+      22      10
+      23      10
+      24      10
+      25      10
+      26      10
+      27      10
+      28      12
+      29      12
+      2a      13
+      2b      13
+      2c      14
+      2f      16
+      30      16
+      31      17
+      32      17
+      33      18
+      36      20
+      37      20
+      38      21
+      39      21
+      3a      21
+      3b      22
+      3e      24
+      3f      24
+      40      25
+      41      25
+      42      28
+      43      28
+      44      28
+      45      28
+   }
+}
+
+Lines mapping:
+14 <-> 7
+15 <-> 8
+16 <-> 11
+18 <-> 13
+19 <-> 14
+20 <-> 15
+22 <-> 17
+23 <-> 18
+24 <-> 19
+26 <-> 21
+27 <-> 22
+28 <-> 23
+30 <-> 25
+31 <-> 26
+35 <-> 29

testData/src/java16/pkg/TestPatternMatchingReturn.java

@@ -0,0 +1,23 @@
+package pkg;
+
+public class TestPatternMatchingReturn {
+  public String getPattern(Object obj) {
+    if (obj instanceof String s) {
+      return s;
+    }
+
+    System.out.println("filler");
+
+    return null;
+  }
+
+  public String get(Object obj) {
+    if (obj instanceof String) {
+      return (String) obj;
+    }
+
+    System.out.println("filler");
+
+    return null;
+  }
+}

testData/src/java17/pkg/TestSwitchOnEnumFake.java

@@ -0,0 +1,37 @@
+package pkg;
+
+public class TestSwitchOnEnumFake {
+  enum Values {
+    A,
+    B,
+    C,
+    D
+  }
+
+  public byte[] values = new byte[Values.values().length];
+
+  public int test(Values v) {
+    int a = 0;
+    int b = 0;
+    switch (values[v.ordinal()]) {
+      case 1 -> {
+        a = 1;
+        b = 2;
+      }
+      case 2 -> {
+        a = 2;
+        b = 4;
+      }
+      case 3 -> {
+        a = 3;
+        b = 6;
+      }
+      default -> {
+        a = 1;
+        b = 1;
+      }
+    }
+
+    return a + b;
+  }
+}