Implement <filesystem>

This patch implements the <filesystem> header and uses that
to provide <experimental/filesystem>.

Unlike other standard headers, the symbols needed for <filesystem>
have not yet been placed in libc++.so. Instead they live in the
new libc++fs.a library. Users of filesystem are required to link this
library. (Also note that libc++experimental no longer contains the
definition of <experimental/filesystem>, which now requires linking libc++fs).

The reason for keeping <filesystem> out of the dylib for now is that
it's still somewhat experimental, and the possibility of requiring an
ABI breaking change is very real. In the future the symbols will likely
be moved into the dylib, or the dylib will be made to link libc++fs automagically).

Note that moving the symbols out of libc++experimental may break user builds
until they update to -lc++fs. This should be OK, because the experimental
library provides no stability guarantees. However, I plan on looking into
ways we can force libc++experimental to automagically link libc++fs.

In order to use a single implementation and set of tests for <filesystem>, it
has been placed in a special `__fs` namespace. This namespace is inline in
C++17 onward, but not before that. As such implementation is available
in C++11 onward, but no filesystem namespace is present "directly", and
as such name conflicts shouldn't occur in C++11 or C++14.

llvm-svn: 338093

1 files changed, 5 insertions, 10 deletions

diff --git a/libcxx/test/support/filesystem_include.hpp b/libcxx/test/support/filesystem_include.hpp
index 228e710f3a1..731532a7be9 100644
--- a/libcxx/test/support/filesystem_include.hpp
+++ b/libcxx/test/support/filesystem_include.hpp
@@ -1,18 +1,13 @@
 #ifndef TEST_SUPPORT_FILESYSTEM_INCLUDE_HPP
 #define TEST_SUPPORT_FILESYSTEM_INCLUDE_HPP
 
-#include <ciso646>
-// Test against std::filesystem for STL's other than libc++
-#ifndef _LIBCPP_VERSION
-#define TEST_INCLUDE_STD_FILESYSTEM
-#endif
-
-#ifdef TEST_INCLUDE_STD_FILESYSTEM
 #include <filesystem>
-namespace fs = std::filesystem;
+#include "test_macros.h"
+
+#if defined(_LIBCPP_VERSION) && TEST_STD_VER < 17
+namespace fs = std::__fs::filesystem;
 #else
-#include <experimental/filesystem>
-namespace fs = std::experimental::filesystem;
+namespace fs = std::filesystem;
 #endif
 
 #endif