show class/package conflict only if corresponding subdirectory contains classes so there could be usages with ambiguous imports

java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightClassUtil.java

@@ -279,7 +279,7 @@ public class HighlightClassUtil {
       if (directory instanceof PsiDirectory) {
         String simpleName = aClass.getName();
         PsiDirectory subDirectory = ((PsiDirectory)directory).findSubdirectory(simpleName);
-        if (subDirectory != null && simpleName.equals(subDirectory.getName())) {
+        if (subDirectory != null && simpleName.equals(subDirectory.getName()) && PsiTreeUtil.findChildOfType(subDirectory, PsiJavaFile.class) != null) {
           String message = JavaErrorMessages.message("class.clashes.with.package", name);
           TextRange range = HighlightNamesUtil.getClassDeclarationTextRange(aClass);
           return HighlightInfo.newHighlightInfo(HighlightInfoType.ERROR).range(range).descriptionAndTooltip(message).create();

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlighting/packageClassClashNoClassInDir/pkg/sub.java

@@ -0,0 +1,3 @@
+package pkg;
+
+public class sub { }

java/java-tests/testSrc/com/intellij/codeInsight/daemon/AdvHighlightingTest.java

@@ -307,6 +307,10 @@ public class AdvHighlightingTest extends DaemonAnalyzerTestCase {
     doTest(BASE_PATH + "/packageClassClash2/pkg/Sub.java", BASE_PATH + "/packageClassClash2", false, false);
   }
 
+  public void testPackageAndClassConflictNoClassInSubdir() throws Exception {
+    doTest(BASE_PATH + "/packageClassClashNoClassInDir/pkg/sub.java", BASE_PATH + "/packageClassClashNoClassInDir", false, false);
+  }
+
   // todo[r.sh] IDEA-91596 (probably PJCRE.resolve() should be changed to qualifier-first model)
   //public void testPackageAndClassConflict3() throws Exception {
   //  doTest(BASE_PATH + "/packageClassClash3/test/Test.java", BASE_PATH + "/packageClassClash3", false, false);