Index: libcxx/src/filesystem/operations.cpp
===================================================================
--- libcxx/src/filesystem/operations.cpp
+++ libcxx/src/filesystem/operations.cpp
@@ -1110,7 +1110,7 @@
 path __current_path(error_code* ec) {
   ErrorHandler<path> err("current_path", ec);
 
-#if defined(_LIBCPP_WIN32API)
+#if defined(_LIBCPP_WIN32API) || defined(__GLIBC__) || defined(__APPLE__)
   // Common extension outside of POSIX getcwd() spec, without needing to
   // preallocate a buffer. Also supported by a number of other POSIX libcs.
   int size = 0;