filesystem: fix n4100 conformance for `temp_directory_path`

N4100 states that an error shall be reported if
`!exists(p) || !is_directory(p)`.  We were missing the first half of the
conditional.  Invert the error and normal code paths to make the code
easier to follow.

llvm-svn: 294127

1 files changed, 8 insertions, 0 deletions

diff --git a/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.temp_dir_path/temp_directory_path.pass.cpp b/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.temp_dir_path/temp_directory_path.pass.cpp
index 148564e6196..021dd7fc816 100644
--- a/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.temp_dir_path/temp_directory_path.pass.cpp
+++ b/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.temp_dir_path/temp_directory_path.pass.cpp
@@ -97,6 +97,14 @@ TEST_CASE(basic_tests)
         TEST_CHECK(ec == std::make_error_code(std::errc::permission_denied));
         TEST_CHECK(ret == "");
 
+        // Set the env variable to point to a non-existent dir
+        PutEnv(TC.name, TC.p / "does_not_exist");
+        ec = GetTestEC();
+        ret = temp_directory_path(ec);
+        TEST_CHECK(ec != GetTestEC());
+        TEST_CHECK(ec);
+        TEST_CHECK(ret == "");
+
         // Finally erase this env variable
         UnsetEnv(TC.name);
     }