DivideByZeroInspection: add fix for 0.0/0.0 (replace with NaN)

Fixes IDEA-117884 Inspection "Divide by zero": Recognize 0.0/0.0

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/divideByZero/afterNaN.java

@@ -0,0 +1,6 @@
+// "Replace with 'NaN'" "true"
+class Test {
+  public void test() {
+    double nan = Double.NaN;
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/divideByZero/beforeInt.java

@@ -0,0 +1,6 @@
+// "Replace with 'NaN'" "false"
+class Test {
+  public void test() {
+    double nan = 0/<caret>0;
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/divideByZero/beforeNaN.java

@@ -0,0 +1,6 @@
+// "Replace with 'NaN'" "true"
+class Test {
+  public void test() {
+    double nan = 0.0/<caret>0.0;
+  }
+}

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

@@ -15,17 +15,24 @@
  */
 package com.siyeh.ig.numeric;
 
+import com.intellij.codeInspection.ProblemDescriptor;
 import com.intellij.codeInspection.dataFlow.CommonDataflow;
 import com.intellij.codeInspection.dataFlow.DfaFactType;
 import com.intellij.codeInspection.dataFlow.rangeSet.LongRangeSet;
+import com.intellij.openapi.project.Project;
 import com.intellij.psi.*;
 import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.util.ConstantExpressionUtil;
+import com.intellij.psi.util.PsiTreeUtil;
 import com.siyeh.InspectionGadgetsBundle;
 import com.siyeh.ig.BaseInspection;
 import com.siyeh.ig.BaseInspectionVisitor;
+import com.siyeh.ig.InspectionGadgetsFix;
+import com.siyeh.ig.psiutils.CommentTracker;
 import org.intellij.lang.annotations.Pattern;
+import org.jetbrains.annotations.Nls;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 public class DivideByZeroInspection extends BaseInspection {
   private static final LongRangeSet ZERO_RANGE = LongRangeSet.point(0);
@@ -49,6 +56,21 @@ public class DivideByZeroInspection extends BaseInspection {
     return InspectionGadgetsBundle.message("divide.by.zero.problem.descriptor");
   }
 
+  @Nullable
+  @Override
+  protected InspectionGadgetsFix buildFix(Object... infos) {
+    if (infos.length > 0 && infos[0] instanceof PsiBinaryExpression) {
+      PsiBinaryExpression binOp = (PsiBinaryExpression)infos[0];
+      if (binOp.getOperationTokenType().equals(JavaTokenType.DIV) && isZero(binOp.getLOperand())) {
+        PsiType type = binOp.getType();
+        if (PsiType.DOUBLE.equals(type) || PsiType.FLOAT.equals(type)) {
+          return new ReplaceWithNaNFix();
+        }
+      }
+    }
+    return null;
+  }
+
   @Override
   public BaseInspectionVisitor buildVisitor() {
     return new DivisionByZeroVisitor();
@@ -67,7 +89,7 @@ public class DivideByZeroInspection extends BaseInspection {
       for (int i = 1; i < operands.length; i++) {
         final PsiExpression operand = operands[i];
         if (isZero(operand)) {
-          registerError(operand);
+          registerError(operand, expression);
           return;
         }
       }
@@ -86,15 +108,34 @@ public class DivideByZeroInspection extends BaseInspection {
       }
       registerError(expression);
     }
+  }
 
-    private static boolean isZero(PsiExpression expression) {
-      final Object value = ConstantExpressionUtil.computeCastTo(expression, PsiType.DOUBLE);
-      if (value instanceof Double) {
-        final double constantValue = ((Double)value).doubleValue();
-        if (constantValue == 0.0) return true;
-      }
-      LongRangeSet range = CommonDataflow.getExpressionFact(expression, DfaFactType.RANGE);
-      return ZERO_RANGE.equals(range);
+  private static boolean isZero(PsiExpression expression) {
+    final Object value = ConstantExpressionUtil.computeCastTo(expression, PsiType.DOUBLE);
+    if (value instanceof Double) {
+      final double constantValue = ((Double)value).doubleValue();
+      if (constantValue == 0.0) return true;
+    }
+    LongRangeSet range = CommonDataflow.getExpressionFact(expression, DfaFactType.RANGE);
+    return ZERO_RANGE.equals(range);
+  }
+
+  private static class ReplaceWithNaNFix extends InspectionGadgetsFix {
+    @Override
+    protected void doFix(Project project, ProblemDescriptor descriptor) {
+      PsiBinaryExpression division = PsiTreeUtil.getNonStrictParentOfType(descriptor.getStartElement(), PsiBinaryExpression.class);
+      if (division == null) return;
+      PsiType type = division.getType();
+      if (!(type instanceof PsiPrimitiveType)) return;
+      String className = ((PsiPrimitiveType)type).getBoxedTypeName();
+      new CommentTracker().replaceAndRestoreComments(division, className+".NaN");
+    }
+
+    @Nls(capitalization = Nls.Capitalization.Sentence)
+    @NotNull
+    @Override
+    public String getFamilyName() {
+      return "Replace with 'NaN'";
     }
   }
 }

plugins/InspectionGadgets/testsrc/com/siyeh/ig/numeric/DivideByZeroInspectionFixTest.java

@@ -0,0 +1,21 @@
+// Copyright 2000-2018 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.
+package com.siyeh.ig.numeric;
+
+import com.intellij.codeInsight.daemon.quickFix.LightQuickFixParameterizedTestCase;
+import com.intellij.codeInspection.LocalInspectionTool;
+import org.jetbrains.annotations.NotNull;
+
+public class DivideByZeroInspectionFixTest extends LightQuickFixParameterizedTestCase {
+  @NotNull
+  @Override
+  protected LocalInspectionTool[] configureLocalInspectionTools() {
+    return new LocalInspectionTool[]{new DivideByZeroInspection()};
+  }
+
+  @Override
+  protected String getBasePath() {
+    return "/codeInsight/daemonCodeAnalyzer/quickFix/divideByZero";
+  }
+
+  public void test() {  doAllTests(); }
+}