Fix contravariant casts, primarily in lambdas

Vineflower · Sep 11, 2023 · 392a8f6 · 392a8f6
1 parent 5e8dd19
commit 392a8f6
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Showing 3 changed files with 15 additions and 10 deletions.
diff --git a/src/org/jetbrains/java/decompiler/modules/decompiler/ExprProcessor.java b/src/org/jetbrains/java/decompiler/modules/decompiler/ExprProcessor.java
@@ -1089,16 +1089,19 @@ public static boolean doGenericTypesCast(Exprent ex, VarType left, VarType right
 
   private static boolean shouldGenericTypesCast(Map<VarType, List<VarType>> named, VarType leftType, VarType rightType) {
     if (leftType.isGeneric()) {
+      GenericType genLeft = (GenericType) leftType;
       if (rightType.isGeneric()) {
+        GenericType genRight = (GenericType) rightType;
+
         if (leftType.isSuperset(rightType)) {
           // Casting Clazz<?> to Clazz<T> or Clazz<Concrete>
-          if ((((GenericType) leftType).getWildcard() == GenericType.WILDCARD_NO || ((GenericType) leftType).getWildcard() == GenericType.WILDCARD_EXTENDS) &&
-            ((GenericType) rightType).getWildcard() == GenericType.WILDCARD_SUPER) {
+          if ((genLeft.getWildcard() == GenericType.WILDCARD_NO || genLeft.getWildcard() == GenericType.WILDCARD_EXTENDS) &&
+            genRight.getWildcard() == GenericType.WILDCARD_SUPER) {
 
             boolean ok = true;
-            if (((GenericType) leftType).getWildcard() == GenericType.WILDCARD_EXTENDS) {
+            if (genLeft.getWildcard() == GenericType.WILDCARD_EXTENDS) {
               // Equals, ignoring wildcards
-              if (!((GenericType) leftType).getArguments().isEmpty() && !((GenericType) rightType).getArguments().isEmpty() &&
+              if (!genLeft.getArguments().isEmpty() && !genRight.getArguments().isEmpty() &&
                 leftType.equals(rightType)) {
                 ok = false;
               }
@@ -1109,26 +1112,29 @@ private static boolean shouldGenericTypesCast(Map<VarType, List<VarType>> named,
             }
           }
         } else {
+          if (genLeft.getWildcard() == GenericType.WILDCARD_EXTENDS && genRight.getWildcard() == GenericType.WILDCARD_SUPER) {
+            return true;
+          }
           // Trying to cast two independent generics to each other? Check if they're both the base generic type (i.e. Object)
           // and force a cast if so.
           if (leftType.type == CodeConstants.TYPE_GENVAR && rightType.type == CodeConstants.TYPE_GENVAR
-            && ((GenericType) leftType).getWildcard() == GenericType.WILDCARD_NO && ((GenericType) leftType).getWildcard() == GenericType.WILDCARD_NO) {
+            && genLeft.getWildcard() == GenericType.WILDCARD_NO && genLeft.getWildcard() == GenericType.WILDCARD_NO) {
 
             if (named.containsKey(leftType) && named.containsKey(rightType) && named.get(leftType).contains(VarType.VARTYPE_OBJECT) && named.get(rightType).contains(VarType.VARTYPE_OBJECT)) {
               return true;
             }
           }
         }
 
-        if ((((GenericType) leftType).getWildcard() == GenericType.WILDCARD_NO || ((GenericType) leftType).getWildcard() == GenericType.WILDCARD_SUPER) &&
-          ((GenericType) rightType).getWildcard() == GenericType.WILDCARD_EXTENDS) {
+        if ((genLeft.getWildcard() == GenericType.WILDCARD_NO || genLeft.getWildcard() == GenericType.WILDCARD_SUPER) &&
+          genRight.getWildcard() == GenericType.WILDCARD_EXTENDS) {
           return true;
         }
       } else {
         // Right is not generic
         // Check for casting a concrete rightType to a specific left generic
         // e.g. (List<T>)list where 'list' is List<Object>
-        if (((GenericType) leftType).getWildcard() == GenericType.WILDCARD_NO && ((GenericType) leftType).getArguments().isEmpty()) {
+        if (genLeft.getWildcard() == GenericType.WILDCARD_NO && genLeft.getArguments().isEmpty()) {
           return true;
         }
       }

diff --git a/test/org/jetbrains/java/decompiler/SingleClassesTest.java b/test/org/jetbrains/java/decompiler/SingleClassesTest.java
@@ -763,7 +763,6 @@ private void registerJavaRuntime() {
     // TODO: otherGenericUnmapped loses mapping when it shouldn't
     register(JAVA_8, "TestGenericWildcard");
     register(JAVA_8, "TestGenericObjectType");
-    // TODO: lambda is missing cast
     register(JAVA_8, "TestGenericSubclassTypes");
     // TODO: wrong variable name
     register(JAVA_16_NODEBUG, "TestRecordCanonicalConstructor");

diff --git a/testData/results/pkg/TestGenericSubclassTypes.dec b/testData/results/pkg/TestGenericSubclassTypes.dec
@@ -8,7 +8,7 @@ public interface TestGenericSubclassTypes<T> {
    Stream<TestGenericSubclassTypes.Constant<T>> cons();
 
    default Iterator<TestGenericSubclassTypes.Numerical<T>> get() {
-      return this.cons().map(c -> c).iterator();// 23
+      return this.cons().map(c -> (TestGenericSubclassTypes.Numerical<T>)c).iterator();// 23
    }
 
    default Function<? super TestGenericSubclassTypes.Constant<T>, ? extends TestGenericSubclassTypes.Constant<T>> func() {