Convert FileSystem::Open() to return Expected<FileUP>

Summary:
This patch converts FileSystem::Open from this prototype:

Status
Open(File &File, const FileSpec &file_spec, ...);

to this one:

llvm::Expected<std::unique_ptr<File>>
Open(const FileSpec &file_spec, ...);

This is beneficial on its own, as llvm::Expected is a more modern
and recommended error type than Status.  It is also a necessary step
towards https://reviews.llvm.org/D67891, and further developments
for lldb_private::File.

Reviewers: JDevlieghere, jasonmolenda, labath

Reviewed By: labath

Subscribers: mgorny, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D67996

llvm-svn: 373003

1 files changed, 15 insertions, 0 deletions

diff --git a/lldb/unittests/Host/FileSystemTest.cpp b/lldb/unittests/Host/FileSystemTest.cpp
index 7fea3b3a529..31184d9ad53 100644
--- a/lldb/unittests/Host/FileSystemTest.cpp
+++ b/lldb/unittests/Host/FileSystemTest.cpp
@@ -288,3 +288,18 @@ TEST(FileSystemTest, EnumerateDirectory) {
   EXPECT_THAT(visited,
               testing::UnorderedElementsAre("/foo", "/bar", "/baz", "/qux"));
 }
+
+TEST(FileSystemTest, OpenErrno) {
+#ifdef _WIN32
+  FileSpec spec("C:\\FILE\\THAT\\DOES\\NOT\\EXIST.TXT");
+#else
+  FileSpec spec("/file/that/does/not/exist.txt");
+#endif
+  FileSystem fs;
+  auto file = fs.Open(spec, File::eOpenOptionRead, 0, true);
+  ASSERT_FALSE(file);
+  std::error_code code = errorToErrorCode(file.takeError());
+  EXPECT_EQ(code.category(), std::system_category());
+  EXPECT_EQ(code.value(), ENOENT);
+}
+