src/java.base/share/classes/java/lang/invoke/AbstractValidatingLambdaMetafactory.java

@@ -367,16 +367,48 @@
                  } else {
                      // must be convertible to primitive
                      return !strict;
                  }
              } else {
-                 // both are reference types: fromType should be a superclass of toType.
-                 return !strict || toType.isAssignableFrom(fromType);
+                 // primitive types: fromType and toType are types of the same primitive class
+                 // identity types: fromType should be a superclass of toType.
+                 return !strict || canConvert(fromType, toType);
              }
          }
      }
  
+     /**
+      * Tests if {@code fromType} can be converted to {@code toType}
+      * via an identity conversion, via a widening reference conversion or
+      * via primitive class narrowing and widening conversions.
+      * <p>
+      * If {@code fromType} represents a class or interface, this method
+      * returns {@code true} if {@code toType} is the same as,
+      * or is a superclass or superinterface of, {@code fromType}.
+      * <p>
+      * If {@code fromType} and {@code toType} is of the same primitive class,
+      * this method returns {@code true}.
+      * <p>
+      * Otherwise, this method returns {@code false}.
+      *
+      * @param     fromType the {@code Class} object to be converted from
+      * @param     toType the {@code Class} object to be converted to
+      * @return    {@code true} if {@code fromType} can be converted to {@code toType}
+      */
+     private boolean canConvert(Class<?> fromType, Class<?> toType) {
+         if (toType.isAssignableFrom(fromType)) {
+             return true;
+         }
+ 
+         if (fromType.isPrimitiveClass() && toType.isPrimitiveClass()) {
+             // val projection can be converted to ref projection; or vice verse
+             return fromType.asPrimaryType() == toType.asPrimaryType();
+         }
+ 
+         return false;
+     }
+ 
      /**
       * Check type adaptability for return types --
       * special handling of void type) and parameterized fromType
       * @return True if 'fromType' can be converted to 'toType'
       */