Bug 545518: [12] Flow analysis is skipped for multi-constant case

statement

Also fixes bug 545516 to report usage of multi-constant case statement
preview feature

Change-Id: I7b0428d1e9eb1666847ae8c65f26d7a554da0de4
Signed-off-by: Jay Arthanareeswaran <jarthana@in.ibm.com>

3 files changed, 54 insertions, 12 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 4413510866..4432e80e53 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
@@ -18,6 +18,7 @@ package org.eclipse.jdt.core.tests.compiler.regression;
 
 import java.util.Map;
 
+import org.eclipse.jdt.internal.compiler.classfmt.ClassFileConstants;
 import org.eclipse.jdt.internal.compiler.impl.CompilerOptions;
 
 import junit.framework.Test;
@@ -2267,4 +2268,40 @@ public class SwitchExpressionTest extends AbstractRegressionTest {
 			"A switch expression should have at least one result expression\n" + 
 			"----------\n");
 	}
-}
\ No newline at end of file
+	public void testBug545518() {
+		if (this.complianceLevel < ClassFileConstants.JDK12)
+			return;
+		Map<String, String> options = getCompilerOptions();
+		options.put(CompilerOptions.OPTION_EnablePreviews, CompilerOptions.ENABLED);
+		options.put(CompilerOptions.OPTION_ReportPreviewFeatures, CompilerOptions.WARNING);
+		String message = 
+				"----------\n" + 
+				"1. WARNING in X.java (at line 5)\n" + 
+				"	case \"ABC\", (false ? (String) \"c\" : (String) \"d\") : break;\n" + 
+				"	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n" + 
+				"You are using a preview language feature that may or may not be supported in a future release\n" + 
+				"----------\n" + 
+				"2. WARNING in X.java (at line 5)\n" + 
+				"	case \"ABC\", (false ? (String) \"c\" : (String) \"d\") : break;\n" + 
+				"	                     ^^^^^^^^^^^^\n" + 
+				"Dead code\n" + 
+				"----------\n";
+		
+		this.runNegativeTest(new String[] {
+				"X.java",
+				"public class X {\n" +
+				"  public static void main(String [] args) {\n" +
+				"  	 String arg = \"ABD\";\n" +
+				"    switch(arg) {\n" + 
+				"      case \"ABC\", (false ? (String) \"c\" : (String) \"d\") : break;\n" +
+				"	 }\n" +
+				"  }\n" +
+				"}\n"
+			},
+			message,
+			null,
+			true,
+			new String[] { "--enable-preview"},
+			options);
+	}
+}
diff --git a/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/ast/CaseStatement.java b/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/ast/CaseStatement.java
index d47025f353..cebeb89f5c 100644
--- a/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/ast/CaseStatement.java
+++ b/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/ast/CaseStatement.java
@@ -56,24 +56,26 @@ public FlowInfo analyseCode(
 	FlowInfo flowInfo) {
 	if (this.constantExpressions != null && this.constantExpressions.length > 1) {
 		for (Expression e : this.constantExpressions) {
-			if (e.constant == Constant.NotAConstant
-					&& !e.resolvedType.isEnum()) {
-				currentScope.problemReporter().caseExpressionMustBeConstant(e);
-			}
-			this.constantExpression.analyseCode(currentScope, flowContext, flowInfo);
+			analyseConstantExpression(currentScope, flowContext, flowInfo, e);
 		}
-		
 	} else {
 		if (this.constantExpression != null) {
-			if (this.constantExpression.constant == Constant.NotAConstant
-					&& !this.constantExpression.resolvedType.isEnum()) {
-				currentScope.problemReporter().caseExpressionMustBeConstant(this.constantExpression);
-			}
-			this.constantExpression.analyseCode(currentScope, flowContext, flowInfo);
+			analyseConstantExpression(currentScope, flowContext, flowInfo, this.constantExpression);
 		}
 	}
 	return flowInfo;
 }
+private void analyseConstantExpression(
+		BlockScope currentScope,
+		FlowContext flowContext,
+		FlowInfo flowInfo, 
+		Expression e) {
+	if (e.constant == Constant.NotAConstant
+			&& !e.resolvedType.isEnum()) {
+		currentScope.problemReporter().caseExpressionMustBeConstant(e);
+	}
+	e.analyseCode(currentScope, flowContext, flowInfo);
+}
 
 @Override
 public StringBuffer printStatement(int tab, StringBuffer output) {
diff --git a/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/parser/Parser.java b/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/parser/Parser.java
index 8a13c67062..73a13453b0 100644
--- a/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/parser/Parser.java
+++ b/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/parser/Parser.java
@@ -2234,6 +2234,9 @@ protected void consumeCaseLabel() {
 	if (hasLeadingTagComment(FALL_THROUGH_TAG, caseStatement.sourceStart)) {
 		caseStatement.bits |= ASTNode.DocumentedFallthrough;
 	}
+	if (this.options.sourceLevel <= ClassFileConstants.JDK12 && constantExpressions.length > 1) {
+		problemReporter().previewFeatureUsed(caseStatement.sourceStart, caseStatement.sourceEnd);
+	}
 	pushOnAstStack(caseStatement);
 }
 protected void consumeCastExpressionLL1() {