Disallow conversions from function pointers to void*.

Function pointers and member function pointers cannot be converted to void*.
libc++abi incorrectly allows this conversion for function pointers.

Review URL: http://reviews.llvm.org/D8811

llvm-svn: 236299

libcxxabi/src/private_typeinfo.cpp

@@ -387,9 +387,13 @@ __pointer_type_info::can_catch(const __shim_type_info* thrown_type,
     if (is_equal(__pointee, thrown_pointer_type->__pointee, false))
         return true;
     // bullet 3A
-    if (is_equal(__pointee, &typeid(void), false))
-        return true;
-
+    if (is_equal(__pointee, &typeid(void), false)) {
+        // pointers to functions cannot be converted to void*.
+        // pointers to member functions are not handled here.
+        const __function_type_info* thrown_function =
+            dynamic_cast<const __function_type_info*>(thrown_pointer_type->__pointee);
+        return (thrown_function == nullptr);
+    }
     // Handle pointer to pointer
     const __pointer_type_info* nested_pointer_type =
         dynamic_cast<const __pointer_type_info*>(__pointee);

libcxxabi/test/catch_function_01.pass.cpp

@@ -11,11 +11,19 @@
 
 #include <cassert>
 
+template <class Tp>
+bool can_convert(Tp) { return true; }
+
+template <class>
+bool can_convert(...) { return false; }
+
 void f() {}
 
 int main()
 {
     typedef void Function();
+    assert(!can_convert<Function&>(&f));
+    assert(!can_convert<void*>(&f));
     try
     {
         throw f;     // converts to void (*)()
@@ -25,7 +33,15 @@ int main()
     {
         assert(false);
     }
-    catch (...)
+    catch (void*) // can't catch as void*
+    {
+        assert(false);
+    }
+    catch(Function*)
     {
     }
+    catch (...)
+    {
+        assert(false);
+    }
 }