IDEA-115330 Incorrect "condition is always false"

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/ControlFlowAnalyzer.java

@@ -31,6 +31,7 @@ import com.intellij.util.IncorrectOperationException;
 import com.intellij.util.SmartList;
 import com.intellij.util.containers.ContainerUtil;
 import com.intellij.util.containers.Stack;
+import com.siyeh.ig.numeric.UnnecessaryExplicitNumericCastInspection;
 import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
@@ -1874,7 +1875,13 @@ public class ControlFlowAnalyzer extends JavaElementVisitor {
 
     final PsiTypeElement typeElement = castExpression.getCastType();
     if (typeElement != null && operand != null) {
-      addInstruction(new TypeCastInstruction(castExpression, operand, typeElement.getType()));
+      if (typeElement.getType() instanceof PsiPrimitiveType &&
+          UnnecessaryExplicitNumericCastInspection.isPrimitiveNumericCastNecessary(castExpression)) {
+        addInstruction(new PopInstruction());
+        pushUnknown();
+      } else {
+        addInstruction(new TypeCastInstruction(castExpression, operand, typeElement.getType()));
+      }
     }
     finishElement(castExpression);
   }

java/java-tests/testData/inspection/dataFlow/fixture/PrimitiveCastMayChangeValue.java

@@ -0,0 +1,15 @@
+
+public class BrokenAlignment {
+  private static void foo(long value) {
+    if (value == (byte)value) {
+      System.out.println("1");
+    } else if (value == (short)value) {
+      System.out.println("2");
+    } else if (value == (int)value) {
+      System.out.println("3");
+    } else {
+      System.out.println("4");
+    }
+  }
+
+}

java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTest.java

@@ -122,6 +122,7 @@ public class DataFlowInspectionTest extends LightCodeInsightFixtureTestCase {
   }
 
   public void testPreserveNullableOnUncheckedCast() throws Throwable { doTest(); }
+  public void testPrimitiveCastMayChangeValue() throws Throwable { doTest(); }
 
   public void testPassingNullableIntoVararg() throws Throwable { doTest(); }
   public void testEqualsImpliesNotNull() throws Throwable { doTest(); }

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/numeric/UnnecessaryExplicitNumericCastInspection.java

@@ -140,7 +140,7 @@ public class UnnecessaryExplicitNumericCastInspection extends BaseInspection {
     }
   }
 
-  static boolean isPrimitiveNumericCastNecessary(PsiTypeCastExpression expression) {
+  public static boolean isPrimitiveNumericCastNecessary(PsiTypeCastExpression expression) {
     final PsiType castType = expression.getType();
     if (castType == null) {
       return true;