Add support for trailing return or throws for pattern instanceof cleanup (#2148)

- modify PatternInstanceofToSwitchFixCore to recgonize the absence of
  an else for the last if statement and if the following statement is
  a return or throws statement, treat it as if it were in an else
- add tests to CleanUpTest21 and CleanUpTest22
- fixes #2143

Author: jjohnstn

org.eclipse.jdt.core.manipulation/core extension/org/eclipse/jdt/internal/corext/fix/PatternInstanceofToSwitchFixCore.java

@@ -231,6 +231,15 @@ private PatternToSwitchExpressionOperation getOperation(List<IfStatement> ifStat
 				List<SwitchCaseSection> returnList= new ArrayList<>();
 				String assignmentName= null;
 				IVariableBinding assignmentBinding= null;
+				Statement addedSibling= null;
+				if (remainingStatement == null) {
+					IfStatement lastIfStatement= ifStatements.get(ifStatements.size() - 1);
+					Statement sibling= ASTNodes.getNextSibling(lastIfStatement);
+					if (sibling instanceof ReturnStatement || sibling instanceof ThrowStatement) {
+						remainingStatement= sibling;
+						addedSibling= sibling;
+					}
+				}
 				if (remainingStatement == null || ASTNodes.asList(remainingStatement).size() == 0) {
 					return null;
 				}
@@ -322,10 +331,10 @@ private PatternToSwitchExpressionOperation getOperation(List<IfStatement> ifStat
 				}
 				if (returnList.size() + throwList.size() == extendedCases.size()) {
 					return new PatternToSwitchExpressionOperation(ifStatements, switchExpression, extendedCases,
-							true, null, null);
+							addedSibling, true, null, null);
 				} else if (assignmentList.size() == extendedCases.size()) {
 					return new PatternToSwitchExpressionOperation(ifStatements, switchExpression, extendedCases,
-							false, assignmentName, assignmentBinding);
+							addedSibling, false, assignmentName, assignmentBinding);
 				}
 				return null;
 			}
@@ -554,16 +563,18 @@ public static class PatternToSwitchExpressionOperation extends CompilationUnitRe
 		private List<IfStatement> ifStatements;
 		private Expression switchExpression;
 		private List<SwitchCaseSection> cases;
+		private Statement addedSibling;
 		private boolean createReturnStatement;
 		private String varName;
 		private IVariableBinding assignmentBinding;
 
 		public PatternToSwitchExpressionOperation(final List<IfStatement> ifStatements, final Expression switchExpression,
-				final List<SwitchCaseSection> cases, final boolean createReturnStatement,
+				final List<SwitchCaseSection> cases, final Statement addedSibling, final boolean createReturnStatement,
 				final String varName, final IVariableBinding assignmentBinding) {
 			this.ifStatements= ifStatements;
 			this.switchExpression= switchExpression;
 			this.cases= cases;
+			this.addedSibling= addedSibling;
 			this.createReturnStatement= createReturnStatement;
 			this.varName= varName;
 			this.assignmentBinding= assignmentBinding;
@@ -732,6 +743,9 @@ public void rewriteAST(CompilationUnitRewrite cuRewrite, LinkedProposalModelCore
 					rewrite.remove(ifStatements.get(i), group);
 				}
 			}
+			if (addedSibling != null) {
+				rewrite.remove(addedSibling, group);
+			}
 		}
 
 	}

org.eclipse.jdt.ui.tests/ui/org/eclipse/jdt/ui/tests/quickfix/CleanUpTest21.java

@@ -695,6 +695,70 @@ public int foo(Object y) {
 		assertRefactoringResultAsExpected(new ICompilationUnit[] { cu1 }, new String[] { expected1 }, null);
 	}
 
+	@Test
+	public void testPatternInstanceofToSwitchExpression5() throws Exception {
+		Hashtable<String, String> options= JavaCore.getOptions();
+		options.put(DefaultCodeFormatterConstants.FORMATTER_TAB_CHAR, JavaCore.TAB);
+		JavaCore.setOptions(options);
+		IPackageFragment pack1= fSourceFolder.createPackageFragment("test1", false, null);
+		String sample= """
+			package test1;
+
+			public class E {
+				int i;
+				double d;
+				boolean b;
+
+				public int square(int x) {
+					return x*x;
+				}
+				public int foo(Object y) {
+					if (y instanceof final Integer xint) {
+						return xint;
+					}
+					if (y instanceof final Double xdouble) {
+						return square(8); // square
+					} else if (y instanceof final Boolean xboolean) {
+						throw new NullPointerException();
+					} else if (y == null) {
+						return 7;
+					}
+					return 11;
+				}
+			}
+			""";
+		ICompilationUnit cu1= pack1.createCompilationUnit("E.java", sample, false, null);
+
+		enable(CleanUpConstants.USE_SWITCH_FOR_INSTANCEOF_PATTERN);
+
+		sample= """
+			package test1;
+
+			public class E {
+				int i;
+				double d;
+				boolean b;
+
+				public int square(int x) {
+					return x*x;
+				}
+				public int foo(Object y) {
+					return switch (y) {
+						case Integer xint -> xint;
+						case Double xdouble -> square(8); // square
+						case Boolean xboolean -> throw new NullPointerException();
+						case null -> 7;
+						default -> 11;
+					};
+				}
+			}
+			""";
+		String expected1= sample;
+
+		assertRefactoringResultAsExpected(new ICompilationUnit[] { cu1 }, new String[] { expected1 }, null);
+	}
+
+	@Test
 	public void testNoPatternInstanceofToSwitch1() throws Exception {
 		Hashtable<String, String> options= JavaCore.getOptions();
 		options.put(DefaultCodeFormatterConstants.FORMATTER_TAB_CHAR, JavaCore.TAB);

org.eclipse.jdt.ui.tests/ui/org/eclipse/jdt/ui/tests/quickfix/CleanUpTest22.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2020, 2024 Red Hat Inc. and others.
+ * Copyright (c) 2020, 2025 Red Hat Inc. and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -247,5 +247,64 @@ public int foo(Object y) {
 
 		assertRefactoringResultAsExpected(new ICompilationUnit[] { cu1 }, new String[] { expected1 }, null);
 	}
+	@Test
+	public void testPatternInstanceofToSwitchExpression2() throws Exception {
+		Hashtable<String, String> options= JavaCore.getOptions();
+		options.put(DefaultCodeFormatterConstants.FORMATTER_TAB_CHAR, JavaCore.TAB);
+		JavaCore.setOptions(options);
+		IPackageFragment pack1= fSourceFolder.createPackageFragment("test1", false, null);
+		String sample= """
+			package test1;
+
+			public class E {
+				int i;
+				double d;
+				boolean b;
+
+				public int square(int x) {
+					return x*x;
+				}
+				public int foo(Object y) {
+					if (y instanceof final Integer xint) {
+						return xint;
+					}
+					if (y instanceof final Double xdouble) {
+						return square(8); // square
+					} else if (y instanceof final Boolean xboolean) {
+						throw new NullPointerException();
+					}
+					return 11;
+				}
+			}
+			""";
+		ICompilationUnit cu1= pack1.createCompilationUnit("E.java", sample, false, null);
+
+		enable(CleanUpConstants.USE_SWITCH_FOR_INSTANCEOF_PATTERN);
+
+		sample= """
+			package test1;
+
+			public class E {
+				int i;
+				double d;
+				boolean b;
+
+				public int square(int x) {
+					return x*x;
+				}
+				public int foo(Object y) {
+					return switch (y) {
+						case Integer xint -> xint;
+						case Double _ -> square(8); // square
+						case Boolean _ -> throw new NullPointerException();
+						case null, default -> 11;
+					};
+				}
+			}
+			""";
+		String expected1= sample;
+
+		assertRefactoringResultAsExpected(new ICompilationUnit[] { cu1 }, new String[] { expected1 }, null);
+	}
 
 }