ControlFlowUtils#isReachable: switch expression handling fixed

Fixes IDEA-192129 Logic is changed when an 'if' statement is simplified

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/ControlFlowUtils.java

@@ -993,8 +993,12 @@ public class ControlFlowUtils {
    */
   public static boolean isReachable(@NotNull PsiStatement statement) {
     ControlFlow flow;
-    PsiCodeBlock block = PsiTreeUtil.getParentOfType(statement, PsiCodeBlock.class);
-    if (block == null) return true;
+    PsiElement block = statement;
+    do {
+      block = PsiTreeUtil.getParentOfType(block, PsiCodeBlock.class);
+      if (block == null) return true;
+    }
+    while (block.getParent() instanceof PsiSwitchStatement);
     try {
       flow = ControlFlowFactory.getInstance(statement.getProject())
         .getControlFlow(block, LocalsOrMyInstanceFieldsControlFlowPolicy.getInstance());

plugins/InspectionGadgets/test/com/siyeh/igfixes/controlflow/trivialIf/InSwitch.after.java

@@ -0,0 +1,17 @@
+// Copyright 2000-2017 JetBrains s.r.o.
+// Use of this source code is governed by the Apache 2.0 license that can be
+// found in the LICENSE file.
+class InCodeBlock {
+  private static boolean original(boolean first, boolean second, int i) {
+    switch (i) {
+      case 0:
+        return false;
+      case 1:
+        if (first)
+            return second;
+        return false;
+      default:
+        return true;
+    }
+  }
+}

plugins/InspectionGadgets/test/com/siyeh/igfixes/controlflow/trivialIf/InSwitch.java

@@ -0,0 +1,18 @@
+// Copyright 2000-2017 JetBrains s.r.o.
+// Use of this source code is governed by the Apache 2.0 license that can be
+// found in the LICENSE file.
+class InCodeBlock {
+  private static boolean original(boolean first, boolean second, int i) {
+    switch (i) {
+      case 0:
+        return false;
+      case 1:
+        if (first)
+          i<caret>f (second)
+            return true;
+        return false;
+      default:
+        return true;
+    }
+  }
+}

plugins/InspectionGadgets/testsrc/com/siyeh/ig/fixes/controlflow/TrivialIfFixTest.java

@@ -37,4 +37,5 @@ public class TrivialIfFixTest extends IGQuickFixesTestCase {
   public void testParentheses() { doTest(); }
   public void testNested() { doTest(); }
   public void testInCodeBlock() { doTest(); }
+  public void testInSwitch() { doTest(); }
 }