Add static assertions to std::function, so that more user-friendly
diagnostics are given when trying to store a non-copyable target object.
These preconditions were added as "Mandates:" by LWG 2447, but I'm
committing them separately from implementing that, to allow just this
change to be backported more easily.
Signed-off-by: Jonathan Wakely <jwak...@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/std_function.h (function::function(F)): Add
static assertions to check constructibility requirements.
Tested powerpc64le-linux. Committed to trunk.
commit 8cf428bfd3ca967b3d135e311d3e391998a39335
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Thu Aug 26 13:13:27 2021
libstdc++: Add static assertions for std::function requirements
Add static assertions to std::function, so that more user-friendly
diagnostics are given when trying to store a non-copyable target object.
These preconditions were added as "Mandates:" by LWG 2447, but I'm
committing them separately from implementing that, to allow just this
change to be backported more easily.
Signed-off-by: Jonathan Wakely <jwak...@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/std_function.h (function::function(F)): Add
static assertions to check constructibility requirements.
diff --git a/libstdc++-v3/include/bits/std_function.h
b/libstdc++-v3/include/bits/std_function.h
index fb86ff1c5f8..e081cd81ef4 100644
--- a/libstdc++-v3/include/bits/std_function.h
+++ b/libstdc++-v3/include/bits/std_function.h
@@ -422,6 +422,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
function(_Functor __f)
: _Function_base()
{
+ static_assert(is_copy_constructible<_Functor>::value,
+ "std::function target must be copy-constructible");
+ static_assert(is_constructible<_Functor, _Functor>::value,
+ "std::function target must be constructible from the "
+ "constructor argument");
+
using _My_handler = _Function_handler<_Res(_ArgTypes...), _Functor>;
if (_My_handler::_M_not_empty_function(__f))
