[libc++] Suppress -Wctad-maybe-unsupported on types w/o deduction guides

There are a handful of standard library types that are intended
to support CTAD but don't need any explicit deduction guides to
do so.

This patch adds a dummy deduction guide to those types to suppress
-Wctad-maybe-unsupported (which gets emitted in user code).

This is a re-application of the original patch by Eric Fiselier in
fcd549a7d828 which had been reverted due to reasons lost at this point.
I also added the macro to a few more types. Reviving this patch was
prompted by the discussion on https://llvm.org/D133425.

Differential Revision: https://reviews.llvm.org/D133535

1 files changed, 1 insertions, 0 deletions

diff --git a/libcxx/src/filesystem/operations.cpp b/libcxx/src/filesystem/operations.cpp
index 61c643cb..fc14778 100644
--- a/libcxx/src/filesystem/operations.cpp
+++ b/libcxx/src/filesystem/operations.cpp
@@ -1408,6 +1408,7 @@ struct scope_exit {
 private:
   Cleanup cleanup_;
 };
+_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(scope_exit);
 
 uintmax_t remove_all_impl(int parent_directory, const path& p, error_code& ec) {
   // First, try to open the path as a directory.