https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77733
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2016-09-28
Ever confirmed|0 |1
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The location for the "cannot bind rvalue reference" error is not a rich
location, so I couldn't figure out how to add a proper fix-it.
This just adds "did you mean std::move(x)?" to the end:
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -6804,7 +6804,8 @@ convert_like_real (conversion *convs, tree expr, tree fn,
int argnum,
if (TYPE_REF_IS_RVALUE (ref_type)
&& lvalue_p (expr))
error_at (loc, "cannot bind rvalue reference of type %qT to "
- "lvalue of type %qT", totype, extype);
+ "lvalue of type %qT; did you mean %<std::move(%E)%>?",
+ totype, extype, expr);
else if (!TYPE_REF_IS_RVALUE (ref_type) && !lvalue_p (expr)
&& !CP_TYPE_CONST_NON_VOLATILE_P (TREE_TYPE (ref_type)))
error_at (loc, "cannot bind non-const lvalue reference of "
Of course sometimes std::move is not the right fix, and it should be
std::forward<something>(x) instead. Maybe it would be possible to detect
whether the expression is a function parameter declared as a forwarding
reference, but that's probably beyond my ken.
Also, if the lvalue is cv-qualified this still suggests std::move(x) even when
that wouldn't work:
move2.cc:13:9: error: cannot bind rvalue reference of type ‘X&&’ to lvalue of
type ‘const X’; did you mean ‘std::move(x)’?
There's room for improvement.
