Java control flow: Fixed false positive for unreachable code in multi-catch clause (IDEA-138978)

java/java-psi-impl/src/com/intellij/psi/controlFlow/ControlFlowAnalyzer.java

@@ -21,10 +21,12 @@ import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.progress.ProgressManager;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.Comparing;
+import com.intellij.openapi.util.Condition;
 import com.intellij.psi.*;
 import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.util.PsiUtil;
+import com.intellij.util.containers.ContainerUtil;
 import com.intellij.util.containers.Stack;
 import gnu.trove.THashMap;
 import gnu.trove.TIntArrayList;
@@ -971,7 +973,7 @@ class ControlFlowAnalyzer extends JavaElementVisitor {
       ProgressManager.checkCanceled();
       PsiParameter parameter = myCatchParameters.get(i);
       PsiType catchType = parameter.getType();
-      if (catchType.isAssignableFrom(throwType) || throwType.isAssignableFrom(catchType)) {
+      if (catchType.isAssignableFrom(throwType) || mightBeAssignableFromSubclass(throwType, catchType)) {
         blocks.add(myCatchBlocks.get(i));
       }
     }
@@ -982,6 +984,18 @@ class ControlFlowAnalyzer extends JavaElementVisitor {
     return blocks;
   }
 
+  private static boolean mightBeAssignableFromSubclass(@NotNull final PsiClassType throwType, @NotNull PsiType catchType) {
+    if (catchType instanceof PsiDisjunctionType) {
+      return ContainerUtil.exists(((PsiDisjunctionType)catchType).getDisjunctions(), new Condition<PsiType>() {
+        @Override
+        public boolean value(PsiType catchDisjunction) {
+          return throwType.isAssignableFrom(catchDisjunction);
+        }
+      });
+    }
+    return throwType.isAssignableFrom(catchType);
+  }
+
   @Override
   public void visitAssertStatement(PsiAssertStatement statement) {
     startElement(statement);

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlighting7/IDEA138978.java

@@ -0,0 +1,22 @@
+class MultiCatch {
+
+  public String get(boolean b) {
+    try {
+      return b ? get1() : get2();
+    } catch (EE1 | EE2 e) {
+      return null; // is reachable
+    } catch (E1 | E2 e) {
+      //
+    }
+    return null;
+  }
+
+  String get1() throws E1 { return "1"; }
+  String get2() throws E2 { return "2"; }
+
+  static class E extends Exception { }
+  static class E1 extends E { }
+  static class E2 extends E { }
+  static class EE1 extends E1 { }
+  static class EE2 extends E2 { }
+}

java/java-tests/testSrc/com/intellij/codeInsight/daemon/LightAdvHighlightingJdk7Test.java

@@ -180,6 +180,7 @@ public class LightAdvHighlightingJdk7Test extends LightDaemonAnalyzerTestCase {
   public void testInaccessibleInferredTypeForVarargsArgument() { doTest(false, false);}
   public void testRuntimeClassCast() { doTest(true, false);}
   public void testTryWithResourcesWithMultipleCloseInterfaces() { doTest(false, false);}
+  public void testIDEA138978() { doTest(false, false); }
 
   public void testJavaUtilCollections_NoVerify() throws Exception {
     PsiClass collectionsClass = getJavaFacade().findClass("java.util.Collections", GlobalSearchScope.moduleWithLibrariesScope(getModule()));