Bug 455828 - Proper handling of 'switch' without explicit default

(including empty switch)

Change-Id: I3e20400f86c5e4273d8b0c62ed9ac3f429a84879
Signed-off-by: Nathan Ridge <zeratul976@hotmail.com>

3 files changed, 58 insertions, 4 deletions

diff --git a/codan/org.eclipse.cdt.codan.core.cxx/src/org/eclipse/cdt/codan/core/cxx/internal/model/cfg/ControlFlowGraphBuilder.java b/codan/org.eclipse.cdt.codan.core.cxx/src/org/eclipse/cdt/codan/core/cxx/internal/model/cfg/ControlFlowGraphBuilder.java
index f158c645f18..5e61a07af6e 100644
--- a/codan/org.eclipse.cdt.codan.core.cxx/src/org/eclipse/cdt/codan/core/cxx/internal/model/cfg/ControlFlowGraphBuilder.java
+++ b/codan/org.eclipse.cdt.codan.core.cxx/src/org/eclipse/cdt/codan/core/cxx/internal/model/cfg/ControlFlowGraphBuilder.java
@@ -338,6 +338,7 @@ public class ControlFlowGraphBuilder {
 		IBasicBlock prev = switchNode;
 		IConnectorNode savedBreak = outerBreak;
 		outerBreak = mergeNode;
+		boolean encounteredDefault = false;
 		try {
 			for (IASTStatement statement : comp.getStatements()) {
 				if (statement instanceof IASTCaseStatement || statement instanceof IASTDefaultStatement) {
@@ -346,6 +347,7 @@ public class ControlFlowGraphBuilder {
 						lbl = factory.createBranchNode(statement);
 					} else if (statement instanceof IASTDefaultStatement) {
 						lbl = factory.createBranchNode(IBranchNode.DEFAULT);
+						encounteredDefault = true;
 					}
 					if (!(prev instanceof IExitNode) && prev != switchNode) {
 						IConnectorNode here = factory.createConnectorNode();
@@ -363,6 +365,16 @@ public class ControlFlowGraphBuilder {
 		} finally {
 			outerBreak = savedBreak;
 		}
+		// If the switch didn't have an explicit 'default' case, we still have to
+		// add an edge for the situation where no case was matched.
+		if (!encounteredDefault) {
+			if (!(prev instanceof IExitNode) && prev != switchNode) {
+				addJump(prev, mergeNode);
+			}
+			IBranchNode defaultBranch = factory.createBranchNode(IBranchNode.DEFAULT);
+			addOutgoing(switchNode, defaultBranch);
+			prev = defaultBranch;
+		}
 		addJump(prev, mergeNode);
 	}
 
diff --git a/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/cfg/ControlFlowGraphTest.java b/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/cfg/ControlFlowGraphTest.java
index 74c9ae466cb..baf1b3763b7 100644
--- a/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/cfg/ControlFlowGraphTest.java
+++ b/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/cfg/ControlFlowGraphTest.java
@@ -638,4 +638,27 @@ public class ControlFlowGraphTest extends CodanFastCxxAstTestCase {
 		IJumpNode case1Jump = (IJumpNode) case1Branch.getOutgoing();
 		assertEquals(swittch.getMergeNode(), case1Jump.getJumpNode());
 	}
+
+	//	int main(int a) {
+	//		switch (a) {
+	//		}
+	//	}
+	public void test_empty_switch() {
+		buildAndCheck(getAboveComment());
+		// Decision node should be optimized away entirely
+		assertFalse(graph.getStartNode() instanceof IDecisionNode);
+	}
+
+	//	int main(int a) {
+	//		switch (a) {
+	//			case 1: {
+	//				break;
+	//			}
+	//		}
+	//	}
+	public void test_switch_no_explicit_default() {
+		buildAndCheck(getAboveComment());
+		IDecisionNode swittch = (IDecisionNode) graph.getStartNode().getOutgoing();
+		assertTrue(swittch.getOutgoingSize() == 2);
+	}
 }
diff --git a/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/internal/checkers/ReturnCheckerTest.java b/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/internal/checkers/ReturnCheckerTest.java
index a5b01093749..f1349c634b5 100644
--- a/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/internal/checkers/ReturnCheckerTest.java
+++ b/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/internal/checkers/ReturnCheckerTest.java
@@ -241,10 +241,20 @@ public class ReturnCheckerTest extends CheckerTestCase {
 //	{
 //	    switch (g()) {
 //	      case 1: return 1;
-//	      case 2:
-//	        return 0;
+//	      case 2: return 0;
 //	}
-	public void testBranchesSwitch_Bug343767() {
+	public void testBranchesSwitch_Bug343767a() {
+		loadCodeAndRunCpp(getAboveComment());
+		checkErrorLine(1);
+	}
+//	int f()
+//	{
+//	    switch (g()) {
+//	      case 1: return 1;
+//	      case 2: return 0;
+//	      default: return -1;
+//	}
+	public void testBranchesSwitch_Bug343767b() {
 		loadCodeAndRunCpp(getAboveComment());
 		checkNoErrors();
 	}
@@ -429,4 +439,13 @@ public class ReturnCheckerTest extends CheckerTestCase {
 		// Just check that codan runs without any exceptions being thrown.
 		loadCodeAndRunCpp(getAboveComment());
 	}
-}
\ No newline at end of file
+
+	//	int foo(int x) {  // no warning
+	//	    switch (x) {
+	//	    }
+	//	}
+	public void testEmptySwitch_455828() throws Exception {
+		loadCodeAndRunCpp(getAboveComment());
+		checkErrorLine(1);
+	}
+}