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| -rw-r--r-- | www/compatibility.html | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/www/compatibility.html b/www/compatibility.html index c3b467f43b..bc34a863f5 100644 --- a/www/compatibility.html +++ b/www/compatibility.html @@ -40,6 +40,7 @@ <ul> <li><a href="#super-cast">Cast of super</a></li> <li><a href="#sizeof-interface">Size of interfaces</a></li> + <li><a href="#objc_objs-cast">Internal Objective-C types</a></li> </ul> </li> <li><a href="#c++">C++ compatibility</a> @@ -234,6 +235,27 @@ this problem, use the Objective-C runtime API function </pre> <!-- ======================================================================= --> +<h3 id="objc_objs-cast">Internal Objective-C types</h3> +<!-- ======================================================================= --> + +<p>GCC allows using pointers to internal Objective-C objects, <tt>struct objc_object*</tt>, +<tt>struct objc_selector*</tt>, and <tt>struct objc_class*</tt> in place of the types +<tt>id</tt>, <tt>SEL</tt>, and <tt>Class</tt> respectively. Clang treats the +internal Objective-C structures as implementation detail and won't do implicit conversions: + +<pre> +t.mm:11:2: error: no matching function for call to 'f' + f((struct objc_object *)p); + ^ +t.mm:5:6: note: candidate function not viable: no known conversion from 'struct objc_object *' to 'id' for 1st argument +void f(id x); + ^ +</pre> + +<p>Code should use types <tt>id</tt>, <tt>SEL</tt>, and <tt>Class</tt> +instead of the internal types.</p> + +<!-- ======================================================================= --> <h2 id="c++">C++ compatibility</h3> <!-- ======================================================================= --> |