[clangd] Remove Tagged and some related APIs from ClangdServer.

Context can do what Tagged was intended to support (snapshot filesystems),
and less intrusively.
getTaggedFileSystem() no longer needs a filename.

Cleanups while here:
 - code-complete now returns errors as Expected, like other functions
 - added an alias Callback<T> for the usual callback function type

llvm-svn: 327344

1 files changed, 3 insertions, 4 deletions

diff --git a/clang-tools-extra/unittests/clangd/TestFS.h b/clang-tools-extra/unittests/clangd/TestFS.h
index b86adbe7374..bec8817c20b 100644
--- a/clang-tools-extra/unittests/clangd/TestFS.h
+++ b/clang-tools-extra/unittests/clangd/TestFS.h
@@ -26,13 +26,12 @@ buildTestFS(llvm::StringMap<std::string> const &Files);
 // A VFS provider that returns TestFSes containing a provided set of files.
 class MockFSProvider : public FileSystemProvider {
 public:
-  Tagged<IntrusiveRefCntPtr<vfs::FileSystem>>
-  getTaggedFileSystem(PathRef File) override;
+  IntrusiveRefCntPtr<vfs::FileSystem> getFileSystem() override {
+    return buildTestFS(Files);
+  }
 
-  llvm::Optional<std::string> ExpectedFile;
   // If relative paths are used, they are resolved with testPath().
   llvm::StringMap<std::string> Files;
-  VFSTag Tag = VFSTag();
 };
 
 // A Compilation database that returns a fixed set of compile flags.