Normalize paths on Windows

1. Normalize paths in LSP document URIs and project root to forward
slash and uppercase drive letters.
2. Normalize paths in compile_commands.json to forward slash and
uppercase drive letters.
3. Normalize paths from directory listing to forward slash. (Drive
letter should be same as input dir path, which is already uppercase
since path of project root dir is normalized)
4. Add llvm::sys::path::convert_to_slash after certain llvm::sys::path
and llvm::fs calls.

src/clang_complete.cc

@@ -28,7 +28,7 @@ namespace {
 std::string StripFileType(const std::string &path) {
   SmallString<128> Ret;
   sys::path::append(Ret, sys::path::parent_path(path), sys::path::stem(path));
-  return Ret.str();
+  return sys::path::convert_to_slash(Ret);
 }
 
 bool LocationInRange(SourceLocation L, CharSourceRange R,

src/clang_utils.cc

@@ -22,7 +22,7 @@ std::string FileName(const FileEntry &file) {
   if (!StartsWith(ret, g_config->projectRoot)) {
     SmallString<256> dest;
     sys::fs::real_path(ret, dest);
-    ret = dest.str();
+    ret = sys::path::convert_to_slash(dest.str());
   }
   return ret;
 }

src/filesystem.cc

@@ -47,7 +47,7 @@ void GetFilesInFolder(std::string folder, bool recursive, bool dir_prefix,
         if (sys::fs::is_regular_file(Status)) {
           if (!dir_prefix)
             path = path.substr(folder.size());
-          handler(path);
+          handler(sys::path::convert_to_slash(path));
         } else if (recursive && sys::fs::is_directory(Status) &&
                    !seen.count(ID = Status.getUniqueID())) {
           curr.push_back(path);

src/indexer.cc

@@ -552,7 +552,7 @@ public:
       if (!llvm::sys::path::is_absolute(Path) &&
           !SM.getFileManager().makeAbsolutePath(Path))
         return -1;
-      it->second.second = Path.str();
+      it->second.second = llvm::sys::path::convert_to_slash(Path.str());
     }
     return it->second.first;
   }

src/lsp.cc

@@ -8,6 +8,7 @@
 
 #include <rapidjson/writer.h>
 
+#include <algorithm>
 #include <stdio.h>
 
 MessageRegistry *MessageRegistry::instance_ = nullptr;
@@ -208,10 +209,15 @@ void lsDocumentUri::SetPath(const std::string &path) {
 }
 
 std::string lsDocumentUri::GetPath() const {
-  if (raw_uri.compare(0, 8, "file:///"))
+  if (raw_uri.compare(0, 7, "file://")) {
+    LOG_S(WARNING)
+        << "Received potentially bad URI (not starting with file://): "
+        << raw_uri;
     return raw_uri;
+  }
   std::string ret;
 #ifdef _WIN32
+  // Skipping the initial "/" on Windows
   size_t i = 8;
 #else
   size_t i = 7;
@@ -224,8 +230,14 @@ std::string lsDocumentUri::GetPath() const {
       ret.push_back(from_hex(raw_uri[i + 1]) * 16 + from_hex(raw_uri[i + 2]));
       i += 2;
     } else
-      ret.push_back(raw_uri[i] == '\\' ? '/' : raw_uri[i]);
+      ret.push_back(raw_uri[i]);
   }
+#ifdef _WIN32
+  std::replace(ret.begin(), ret.end(), '\\', '/');
+  if (ret.size() > 1 && ret[0] >= 'a' && ret[0] <= 'z' && ret[1] == ':') {
+    ret[0] = toupper(ret[0]);
+  }
+#endif
   return ret;
 }
 

src/platform_win.cc

@@ -23,14 +23,19 @@ std::string NormalizePath(const std::string &path) {
   TCHAR buffer[MAX_PATH] = TEXT("");
   TCHAR **lpp_part = {NULL};
 
+  std::string result;
   retval = GetFullPathName(path.c_str(), MAX_PATH, buffer, lpp_part);
   // fail, return original
   if (retval == 0)
-    return path;
+    result = path;
+  else
+    result = buffer;
 
-  std::string result = buffer;
   std::replace(result.begin(), result.end(), '\\', '/');
-  // std::transform(result.begin(), result.end(), result.begin(), ::tolower);
+  // Normalize drive letter.
+  if (result.size() > 1 && result[0] >= 'a' && result[0] <= 'z' &&
+      result[1] == ':')
+    result[0] = toupper(result[0]);
   return result;
 }
 

src/project.cc

@@ -160,7 +160,8 @@ struct ProjectProcessor {
 
     HeaderSearchOptions &HeaderOpts = CI->getHeaderSearchOpts();
     for (auto &E : HeaderOpts.UserEntries) {
-      std::string path = ResolveIfRelative(entry.directory, E.Path);
+      std::string path =
+          NormalizePath(ResolveIfRelative(entry.directory, E.Path));
       switch (E.Group) {
       default:
         config->angle_dirs.insert(path);
@@ -315,8 +316,9 @@ LoadEntriesFromDirectory(ProjectConfig *project,
   ProjectProcessor proc(project);
   for (tooling::CompileCommand &Cmd : CDB->getAllCompileCommands()) {
     Project::Entry entry;
-    entry.directory = std::move(Cmd.Directory);
-    entry.filename = ResolveIfRelative(entry.directory, Cmd.Filename);
+    entry.directory = NormalizePath(Cmd.Directory);
+    entry.filename =
+        NormalizePath(ResolveIfRelative(entry.directory, Cmd.Filename));
     entry.args = std::move(Cmd.CommandLine);
     proc.Process(entry);
     if (Seen.insert(entry.filename).second)