rsmith requested changes to this revision.
rsmith added inline comments.
This revision now requires changes to proceed.
================
Comment at: clang/lib/Sema/SemaCast.cpp:1781-1782
// type T2 using the cast const_cast<T2&&>; and
// -- if T1 is a class type, a prvalue of type T1 can be explicitly
// converted to an xvalue of type T2 using the cast const_cast<T2&&>.
----------------
This is the bullet that causes class pvalues and non-class prvalues to be
treated differently by `const_cast` to an rvalue reference type, and it still
exists unchanged in the latest C++ draft. As far as I can tell, the change here
is not in line with the wording for N4261 / CWG issue 330, which Clang does
implement.
(Now, I think the change you're suggesting here makes a lot of sense, but we
should get agreement in WG21 to fix the language rules first.)
================
Comment at: clang/lib/Sema/SemaCast.cpp:1797-1801
+ // C++17 [expr.const.cast]p3
+ // For two similar types T1 and T2, a prvalue of type T1 may be
explicitly
+ // converted to the type T2 using a const_cast if, considering the
+ // cv-decompositions of both types, each P1i is the same as P2i for all
i.
+ // The result of a const_cast refers to the original entity.
----------------
In (for example) `const_cast<int&&>(0);`, `T1` is `int`, and `T2` is "rvalue
reference to `int`". `T1` and `T2` are not similar types, because they have
different types `U` (for `T1`, `U` is `int`; for `T2`, `U` is "rvalue reference
to `int`"). So this doesn't apply.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D87565/new/
https://reviews.llvm.org/D87565
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
