Bug 545716 - [12] expression switch doesn't consider that having all

cases of an enum is enough to be exhaustive

3 files changed, 31 insertions, 1 deletions

diff --git a/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/SwitchExpressionTest.java b/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/SwitchExpressionTest.java
index e4e6e8ed0b..0d8ac4a28d 100644
--- a/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/SwitchExpressionTest.java
+++ b/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/SwitchExpressionTest.java
@@ -2385,4 +2385,27 @@ public class SwitchExpressionTest extends AbstractRegressionTest {
 		null,
 		new String[] {"--enable-preview"});
 	}
+	public void testBug545916_01() {
+		runConformTest(
+			new String[] {
+				"X.java",
+				"enum X {\n"+
+				"    A, B;\n"+
+				"     \n"+
+				"    @SuppressWarnings(\"preview\")\n"+
+				"    public static void main(String[] args) {\n"+
+				"         X myEnum = X.A;\n"+
+				"         int o;\n"+
+				"         var f = switch(myEnum) {\n"+
+				"             case A -> o = 5;\n"+
+				"             case B -> o = 10;\n"+
+				"         };\n"+
+				"         System.out.println(o);\n"+
+				"     }\n"+
+				"} \n"
+		},
+		"5",
+		null,
+		new String[] {"--enable-preview"});
+	}
 }
diff --git a/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/ast/SwitchExpression.java b/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/ast/SwitchExpression.java
index faba6e578f..1130f69256 100644
--- a/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/ast/SwitchExpression.java
+++ b/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/ast/SwitchExpression.java
@@ -160,6 +160,10 @@ public class SwitchExpression extends SwitchStatement implements IPolyExpression
 		}
 	}
 	@Override
+	protected boolean checkNullDefaultFlow() { // JLS 12 16.1.8 
+		return !this.switchLabeledRules;
+	}
+	@Override
 	public Expression[] getPolyExpressions() {
 		List<Expression> polys = new ArrayList<>();
 		for (Expression e : this.resultExpressions) {
diff --git a/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/ast/SwitchStatement.java b/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/ast/SwitchStatement.java
index a694b0a101..eebcfca755 100644
--- a/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/ast/SwitchStatement.java
+++ b/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/ast/SwitchStatement.java
@@ -112,6 +112,9 @@ public class SwitchStatement extends Expression {
 	protected void completeNormallyCheck(BlockScope blockScope) {
 		// do nothing
 	}
+	protected boolean checkNullDefaultFlow() {
+		return true;
+	}
 	@Override
 	public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext, FlowInfo flowInfo) {
 		try {
@@ -175,7 +178,7 @@ public class SwitchStatement extends Expression {
 				this.synthetic = sourceTypeBinding.addSyntheticMethodForSwitchEnum(resolvedTypeBinding, this);
 			}
 			// if no default case, then record it may jump over the block directly to the end
-			if (this.defaultCase == null) {
+			if (this.defaultCase == null && checkNullDefaultFlow()) {
 				// only retain the potential initializations
 				flowInfo.addPotentialInitializationsFrom(caseInits.mergedWith(switchContext.initsOnBreak));
 				this.mergedInitStateIndex = currentScope.methodScope().recordInitializationStates(flowInfo);