[java-inspection] IJ-CR-177592 IDEA-375813 It seems dataflow join works wrong for branching with division by zero

- added descriptions and a new option

GitOrigin-RevId: 4d105d96b1b8fd0bae8560134479c959aaaa7d20

java/java-analysis-impl/resources/messages/InspectionGadgetsBundle.properties

@@ -849,6 +849,9 @@ comparison.of.short.and.char.problem.descriptor=Equality comparison <code>#ref</
 big.decimal.equals.problem.descriptor=<code>#ref()</code> between BigDecimal values should probably be 'compareTo()' #loc
 divide.by.zero.problem.descriptor=Division by zero #loc
 divide.by.zero.problem.may.descriptor=Maybe division by zero #loc
+divide.by.zero.problem.may.option=Report conditional divide-by-zero
+divide.by.zero.problem.may.option.description=Highlights divisions that can become zero in some execution branches
+divide.by.zero.problem.may.option.disabled=Don't suggest conditional divide-by-zero problems
 non.reproducible.math.call.problem.descriptor=<code>Math.#ref()</code> may produce non-reproducible results #loc
 constant.math.call.problem.descriptor=Constant call to <code>#ref()</code> can be simplified #loc
 floating.point.equality.problem.descriptor=<code>#ref</code>: floating-point values compared for exact equality #loc

java/java-analysis-impl/src/com/siyeh/ig/numeric/DivideByZeroInspection.java

@@ -17,10 +17,12 @@ package com.siyeh.ig.numeric;
 
 import com.intellij.codeInspection.CommonQuickFixBundle;
 import com.intellij.codeInspection.LocalQuickFix;
+import com.intellij.codeInspection.UpdateInspectionOptionFix;
 import com.intellij.codeInspection.dataFlow.CommonDataflow;
 import com.intellij.codeInspection.dataFlow.rangeSet.LongRangeSet;
 import com.intellij.codeInspection.dataFlow.types.DfIntType;
 import com.intellij.codeInspection.dataFlow.types.DfType;
+import com.intellij.codeInspection.options.OptPane;
 import com.intellij.modcommand.ModPsiUpdater;
 import com.intellij.modcommand.PsiUpdateModCommandQuickFix;
 import com.intellij.openapi.project.Project;
@@ -41,8 +43,23 @@ import org.jetbrains.annotations.Nullable;
 
 import java.util.List;
 
+import static com.intellij.codeInspection.options.OptPane.checkbox;
+import static com.intellij.codeInspection.options.OptPane.pane;
+
 public final class DivideByZeroInspection extends BaseInspection {
 
+
+  @SuppressWarnings("PublicField")
+  public boolean reportMayBeZero = true;
+
+  @Override
+  public @NotNull OptPane getOptionsPane() {
+    return pane(
+      checkbox("reportMayBeZero",
+               InspectionGadgetsBundle.message("divide.by.zero.problem.may.option"))
+        .description(InspectionGadgetsBundle.message("divide.by.zero.problem.may.option.description")));
+  }
+
   @Pattern(VALID_ID_PATTERN)
   @Override
   public @NotNull String getID() {
@@ -69,6 +86,11 @@ public final class DivideByZeroInspection extends BaseInspection {
         }
       }
     }
+    if (infos.length > 1 && infos[1] instanceof ThreeState threeState && threeState == ThreeState.UNSURE) {
+      return LocalQuickFix.from(new UpdateInspectionOptionFix(
+        this, "reportMayBeZero",
+        InspectionGadgetsBundle.message("divide.by.zero.problem.may.option.disabled", false), false));
+    }
     return null;
   }
 
@@ -77,7 +99,7 @@ public final class DivideByZeroInspection extends BaseInspection {
     return new DivisionByZeroVisitor();
   }
 
-  private static class DivisionByZeroVisitor extends BaseInspectionVisitor {
+  private class DivisionByZeroVisitor extends BaseInspectionVisitor {
 
     @Override
     public void visitPolyadicExpression(@NotNull PsiPolyadicExpression expression) {
@@ -112,7 +134,7 @@ public final class DivideByZeroInspection extends BaseInspection {
     }
   }
 
-  private static ThreeState isZero(PsiExpression expression) {
+  private ThreeState isZero(PsiExpression expression) {
     final Object value = ConstantExpressionUtil.computeCastTo(expression, PsiTypes.doubleType());
     if (value instanceof Double) {
       final double constantValue = ((Double)value).doubleValue();
@@ -123,6 +145,7 @@ public final class DivideByZeroInspection extends BaseInspection {
     if (val != null) {
       return val.doubleValue() == 0.0 ? ThreeState.YES : ThreeState.NO;
     }
+    if(!reportMayBeZero) return ThreeState.NO;
     if (dfType instanceof DfIntType dfIntType) {
       LongRangeSet range = dfIntType.getRange();
       List<LongRangeSet> ranges = range.asRanges();

java/java-impl/resources/inspectionDescriptions/DivideByZero.html

@@ -5,6 +5,7 @@ Such expressions will produce an <code>Infinity</code>, <code>-Infinity</code> o
 and will throw an <code>ArithmeticException</code> for integers.
 <p>When the expression has a <code>NaN</code> result, the fix suggests replacing the division expression with the <code>NaN</code> constant.
 <!-- tooltip end -->
-
+<p>Use the <b>Report conditional divide-by-zero</b> option to report divisions where the divisor may be zero in some execution paths.
+  This may occasionally produce false positives.
 </body>
 </html>