[Decompiler] Fix short name imports shadowed by super inner classes (IDEA-196315)

plugins/java-decompiler/engine/src/org/jetbrains/java/decompiler/main/collectors/ImportCollector.java

@@ -5,6 +5,7 @@
 
 import org.jetbrains.java.decompiler.main.ClassesProcessor.ClassNode;
 import org.jetbrains.java.decompiler.main.DecompilerContext;
+import org.jetbrains.java.decompiler.struct.attr.StructInnerClassesAttribute;
 import org.jetbrains.java.decompiler.util.TextBuffer;
 import org.jetbrains.java.decompiler.struct.StructClass;
 import org.jetbrains.java.decompiler.struct.StructContext;
@@ -20,6 +21,7 @@ public class ImportCollector {
   private final Set<String> setNotImportedNames = new HashSet<>();
   // set of field names in this class and all its predecessors.
   private final Set<String> setFieldNames = new HashSet<>();
+  private final Set<String> setInnerClassNames = new HashSet<>();
   private final String currentPackageSlash;
   private final String currentPackagePoint;
 
@@ -37,15 +39,37 @@ public ImportCollector(ClassNode root) {
     }
 
     Map<String, StructClass> classes = DecompilerContext.getStructContext().getClasses();
+    LinkedList<String> queue = new LinkedList<>();
     StructClass currentClass = root.classStruct;
     while (currentClass != null) {
+      if (currentClass.superClass != null) {
+        queue.add(currentClass.superClass.getString());
+      }
+
+      Collections.addAll(queue, currentClass.getInterfaceNames());
+
       // all field names for the current class ..
       for (StructField f : currentClass.getFields()) {
         setFieldNames.add(f.getName());
       }
 
+      // .. all inner classes for the current class ..
+      if (currentClass.hasAttribute(StructInnerClassesAttribute.ATTRIBUTE_INNER_CLASSES)) {
+        StructInnerClassesAttribute attribute =
+                            (StructInnerClassesAttribute)currentClass.getAttribute(StructInnerClassesAttribute.ATTRIBUTE_INNER_CLASSES);
+
+        for (StructInnerClassesAttribute.Entry entry : attribute.getEntries()) {
+          if (entry.enclosingName != null && entry.enclosingName.equals(currentClass.qualifiedName)) {
+            setInnerClassNames.add(entry.simpleName);
+          }
+        }
+      }
+
       // .. and traverse through parent.
-      currentClass = currentClass.superClass != null ? classes.get(currentClass.superClass.getString()) : null;
+      currentClass = !queue.isEmpty() ? classes.get(queue.removeFirst()) : null;
+      while (currentClass == null && !queue.isEmpty()) {
+        currentClass = classes.get(queue.removeFirst());
+      }
     }
   }
 
@@ -105,12 +129,14 @@ public String getShortName(String fullName, boolean imported) {
 
     StructContext context = DecompilerContext.getStructContext();
 
-    // check for another class which could 'shadow' this one. Two cases:
+    // check for another class which could 'shadow' this one. Three cases:
     // 1) class with the same short name in the current package
     // 2) class with the same short name in the default package
+    // 3) inner class with the same short name in the current class, a super class, or an implemented interface
     boolean existsDefaultClass =
       (context.getClass(currentPackageSlash + shortName) != null && !packageName.equals(currentPackagePoint)) || // current package
-      (context.getClass(shortName) != null && !currentPackagePoint.isEmpty());  // default package
+      (context.getClass(shortName) != null && !currentPackagePoint.isEmpty()) || // default package
+      setInnerClassNames.contains(shortName); // inner class
 
     if (existsDefaultClass ||
         (mapSimpleNames.containsKey(shortName) && !packageName.equals(mapSimpleNames.get(shortName)))) {

plugins/java-decompiler/engine/test/org/jetbrains/java/decompiler/SingleClassesTest.java

@@ -70,7 +70,8 @@ public void tearDown() {
   @Test public void testAnonymousSignature() { doTest("pkg/TestAnonymousSignature"); }
   @Test public void testLocalsSignature() { doTest("pkg/TestLocalsSignature"); }
   @Test public void testParameterizedTypes() { doTest("pkg/TestParameterizedTypes"); }
-  @Test public void testShadowing() { doTest("pkg/TestShadowing", "pkg/Shadow", "ext/Shadow"); }
+  @Test public void testShadowing() { doTest("pkg/TestShadowing", "pkg/Shadow", "ext/Shadow",
+           "pkg/TestShadowingSuperClass"); }
   @Test public void testStringConcat() { doTest("pkg/TestStringConcat"); }
   @Test public void testJava9StringConcat() { doTest("java9/TestJava9StringConcat"); }
   @Test public void testMethodReferenceSameName() { doTest("pkg/TestMethodReferenceSameName"); }

plugins/java-decompiler/engine/testData/results/TestShadowing.dec

@@ -1,6 +1,7 @@
 package pkg;
 
-class TestShadowing {
+class TestShadowing extends TestShadowingSuperClass {
    ext.Shadow.B instanceOfB = new ext.Shadow.B();
+   java.util.Calendar.Builder calBuilder = new java.util.Calendar.Builder();
 }
 

plugins/java-decompiler/engine/testData/src/pkg/TestShadowing.java

@@ -1,5 +1,12 @@
 package pkg;
 
-class TestShadowing {
+import java.util.Calendar;
+
+class TestShadowing extends TestShadowingSuperClass {
   ext.Shadow.B instanceOfB = new ext.Shadow.B();
+  Calendar.Builder calBuilder = new Calendar.Builder();
+}
+
+class TestShadowingSuperClass {
+  static class Builder { }
 }