[java-inspections] OverwrittenFieldAnalyzer: set initial field write anchor to prevent subtle bugs

GitOrigin-RevId: 5138540545f8553a96a4cad042ed87e71d223dd6

java/java-impl-inspections/src/com/intellij/codeInspection/defUse/OverwrittenFieldAnalyzer.java

@@ -146,6 +146,8 @@ final class OverwrittenFieldAnalyzer {
       return "@" + write + (wasRead ? " (wasRead)" : "");
     }
   }
+  
+  private record EntryPointAnchor() implements DfaAnchor {}
 
   private record WriteAnchorDescriptor(@NotNull DfaVariableValue var) implements VariableDescriptor {
     @Override
@@ -163,6 +165,11 @@ final class OverwrittenFieldAnalyzer {
       return DfWriteTopType.INSTANCE;
     }
 
+    @Override
+    public @NotNull DfType getInitialDfType(@NotNull DfaVariableValue thisValue, @Nullable PsiElement context) {
+      return new DfWriteAnchorType(new EntryPointAnchor(), false);
+    }
+
     @Override
     public String toString() {
       return "writtenAt(" + var + ")";
@@ -220,7 +227,7 @@ final class OverwrittenFieldAnalyzer {
         varsToFlush.forEach(state::flushVariable);
         if (var.getPsiVariable() instanceof PsiField && anchor != null) {
           DfaVariableValue wnr = myFactory.getVarFactory().createVariableValue(new WriteAnchorDescriptor(var));
-          state.meetDfType(wnr, new DfWriteAnchorType(anchor, false));
+          state.updateDfType(wnr, old -> new DfWriteAnchorType(anchor, false));
         }
       }
     }

java/java-tests/testData/inspection/defUse/FieldNoOverwriteEmptyElse.java

@@ -0,0 +1,12 @@
+public class FieldNoOverwriteEmptyElse {
+  boolean myField;
+
+  void test(int x) {
+    if (x != 1) {
+      myField = true;
+    }
+    if (x == 3) {
+      myField = false;
+    } else {}
+  }
+}

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

@@ -62,6 +62,7 @@ public class DefUseTest extends LightJavaCodeInsightFixtureTestCase {
   public void testFieldOverwrite() { doTest(); }
   public void testFieldOverwriteAfterQualifierUpdate() { doTest(); }
   public void testFieldNoOverwrite() { doTest(); }
+  public void testFieldNoOverwriteEmptyElse() { doTest(); }
   public void testAssignmentInCatch() { doTest(); }
 
   public void testFieldCouldBeUsedOutside() { doTest(); }