<html>
<head>
<base href="http://llvm.org/bugs/" />
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Block types are not covariant in their return type and contravariant in their argument types with respect to C++ classes"
href="http://llvm.org/bugs/show_bug.cgi?id=15484">15484</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Block types are not covariant in their return type and contravariant in their argument types with respect to C++ classes
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Macintosh
</td>
</tr>
<tr>
<th>OS</th>
<td>MacOS X
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>C++
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>jppellet@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>This bug is related to this StackOverflow question:
<a href="http://stackoverflow.com/questions/15312774/assigning-block-pointers-differences-between-objective-c-vs-c-classes">http://stackoverflow.com/questions/15312774/assigning-block-pointers-differences-between-objective-c-vs-c-classes</a>
Imagine I have this simple Objective-C class hierarchy:
@interface Fruit : NSObject
@end
@interface Apple : Fruit
@end
Then I can write stuff like this:
Fruit *(^getFruit)();
Apple *(^getApple)();
getFruit = getApple;
This is all good and well — in Objective-C. Now let's try that in C++ or
Objective-C++, supposing we have these similar C++ classes:
class FruitCpp {};
class AppleCpp : public FruitCpp {};
class OrangeCpp : public FruitCpp {};
Sadly, these block assignments don't compile any more:
FruitCpp *(^getFruitCpp)();
AppleCpp *(^getAppleCpp)();
getFruitCpp = getAppleCpp; // error!
Why should it work for Objective-C classes and not C++ classes?</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>