Fix requireNonNull call appearing when the selector is reusable and fix (#436)

default being removed from switch statements that are required to be
exhaustive

Author: coehlrich

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

@@ -3,6 +3,7 @@
 
 import org.jetbrains.java.decompiler.modules.decompiler.exps.ExitExprent;
 import org.jetbrains.java.decompiler.modules.decompiler.exps.Exprent;
+import org.jetbrains.java.decompiler.modules.decompiler.exps.FunctionExprent;
 import org.jetbrains.java.decompiler.modules.decompiler.stats.*;
 import org.jetbrains.java.decompiler.modules.decompiler.stats.Statement.EdgeDirection;
 
@@ -470,7 +471,13 @@ public static boolean hideDefaultSwitchEdges(Statement stat) {
       if (last >= 0) { // empty switch possible
         Statement stlast = swst.getCaseStatements().get(last);
 
-        if (stlast.getExprents() != null && stlast.getExprents().isEmpty()) {
+        boolean needsExhaustive = swst.getCaseValues().stream()
+            .flatMap(List::stream)
+            .filter(exp -> exp instanceof FunctionExprent)
+            .map(exp -> (FunctionExprent) exp)
+            .filter(exp -> exp.getFuncType() == FunctionExprent.FunctionType.INSTANCEOF)
+            .findAny().isPresent();
+        if (stlast.getExprents() != null && stlast.getExprents().isEmpty() && !needsExhaustive) {
           List<StatEdge> edges = stlast.getAllSuccessorEdges();
           // If we don't have an edge from this statement or if the edge that we have isn't explicit, delete the default edge
           if (edges.isEmpty() || !edges.get(0).explicit) {

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

@@ -317,14 +317,22 @@ private static boolean processStatement(SwitchStatement stat, Statement root) {
     // Check for non null
     if (basicHead != null && basicHead.size() >= 1 && realSelector instanceof VarExprent var && !nullCase) {
       Exprent last = basicHead.get(basicHead.size() - 1);
-      if (last instanceof InvocationExprent inv && inv.isStatic() && inv.getClassname().equals("java/util/Objects") && inv.getName().equals("requireNonNull") && inv.getStringDescriptor().equals("(Ljava/lang/Object;)Ljava/lang/Object;") && var.equals(inv.getLstParameters().get(0))) {
-        basicHead.remove(basicHead.size() - 1);
-        // Check for other assignment
-        if (basicHead.size() >= 1 && var.isStack() && !nullCase) {
-          last = basicHead.get(basicHead.size() - 1);
-          if (last instanceof AssignmentExprent assignment && assignment.getLeft() instanceof VarExprent assigned && var.equals(assigned)) {
-            if (!var.isVarReferenced(root, assigned)) {
-              realSelector = assignment.getRight();
+      AssignmentExprent stackAssignment = null;
+      if (last instanceof InvocationExprent inv && inv.isStatic() && inv.getClassname().equals("java/util/Objects") && inv.getName().equals("requireNonNull") && inv.getStringDescriptor().equals("(Ljava/lang/Object;)Ljava/lang/Object;")) {
+        VarExprent requireNonNullStackVar = null;
+        if (inv.getLstParameters().get(0) instanceof VarExprent varExprent) {
+          requireNonNullStackVar = varExprent;
+        }
+        if (basicHead.size() >= 2 && var.isStack() && !nullCase && basicHead.get(basicHead.size() - 2) instanceof AssignmentExprent assignment && assignment.getLeft() instanceof VarExprent assigned && var.equals(assigned) && !var.isVarReferenced(root, assigned, requireNonNullStackVar)) {
+          stackAssignment = assignment;
+        }
+        if (var.equals(inv.getLstParameters().get(0)) || (inv.getLstParameters().get(0).getExprentUse() & Exprent.MULTIPLE_USES) != 0 && inv.getLstParameters().get(0).equals(stackAssignment.getRight())) {
+          basicHead.remove(basicHead.size() - 1);
+          // Check for other assignment
+          if (basicHead.size() >= 1 && var.isStack() && !nullCase) {
+            last = basicHead.get(basicHead.size() - 1);
+            if (stackAssignment != null) {
+              realSelector = stackAssignment.getRight();
               basicHead.remove(basicHead.size() - 1);
             }
           }

testData/results/pkg/TestSwitchPatternMatching15.dec

@@ -18,6 +18,7 @@ public class TestSwitchPatternMatching15 {
          case Number nx:// 15
             System.out.println("Number: " + nx);// 16
             break;// 17
+         default:
       }
    }// 21
 }
@@ -133,7 +134,7 @@ class 'pkg/TestSwitchPatternMatching15' {
       95      18
       96      18
       97      19
-      9d      21
+      9d      22
    }
 }
 
@@ -151,6 +152,6 @@ Lines mapping:
 15 <-> 18
 16 <-> 19
 17 <-> 20
-21 <-> 22
+21 <-> 23
 Not mapped:
 19