Temporarily revert "Add a facility to get system cache directory and use it in clangd"

This reverts commit ad38f4b371.

As it broke building the unittests:

.../sources/llvm-project/llvm/unittests/Support/Path.cpp:334:5: error: use of undeclared identifier 'set'
    set(Value);
    ^
1 error generated.

clang-tools-extra/clangd/index/BackgroundIndexStorage.cpp

@@ -36,13 +36,18 @@ std::string getShardPathFromFilePath(llvm::StringRef ShardRoot,
   return std::string(ShardRootSS.str());
 }
 
-// Uses disk as a storage for index shards.
+// Uses disk as a storage for index shards. Creates a directory called
+// ".clangd/index/" under the path provided during construction.
 class DiskBackedIndexStorage : public BackgroundIndexStorage {
   std::string DiskShardRoot;
 
 public:
-  // Creates `DiskShardRoot` and any parents during construction.
-  DiskBackedIndexStorage(llvm::StringRef Directory) : DiskShardRoot(Directory) {
+  // Sets DiskShardRoot to (Directory + ".clangd/index/") which is the base
+  // directory for all shard files.
+  DiskBackedIndexStorage(llvm::StringRef Directory) {
+    llvm::SmallString<128> CDBDirectory(Directory);
+    llvm::sys::path::append(CDBDirectory, ".clangd", "index");
+    DiskShardRoot = std::string(CDBDirectory.str());
     std::error_code OK;
     std::error_code EC = llvm::sys::fs::create_directories(DiskShardRoot);
     if (EC != OK) {
@@ -95,31 +100,26 @@ public:
 };
 
 // Creates and owns IndexStorages for multiple CDBs.
-// When a CDB root is found, shards are stored in $ROOT/.clangd/index.
-// When no root is found, the fallback path is ~/.cache/clangd/index.
 class DiskBackedIndexStorageManager {
 public:
   DiskBackedIndexStorageManager(
       std::function<llvm::Optional<ProjectInfo>(PathRef)> GetProjectInfo)
       : IndexStorageMapMu(std::make_unique<std::mutex>()),
         GetProjectInfo(std::move(GetProjectInfo)) {
-    llvm::SmallString<128> FallbackDir;
-    if (llvm::sys::path::cache_directory(FallbackDir))
-      llvm::sys::path::append(FallbackDir, "clangd", "index");
-    this->FallbackDir = FallbackDir.str().str();
+    llvm::SmallString<128> HomeDir;
+    llvm::sys::path::home_directory(HomeDir);
+    this->HomeDir = HomeDir.str().str();
   }
 
   // Creates or fetches to storage from cache for the specified project.
   BackgroundIndexStorage *operator()(PathRef File) {
     std::lock_guard<std::mutex> Lock(*IndexStorageMapMu);
-    llvm::SmallString<128> StorageDir(FallbackDir);
-    if (auto PI = GetProjectInfo(File)) {
-      StorageDir = PI->SourceRoot;
-      llvm::sys::path::append(StorageDir, ".clangd", "index");
-    }
-    auto &IndexStorage = IndexStorageMap[StorageDir];
+    Path CDBDirectory = HomeDir;
+    if (auto PI = GetProjectInfo(File))
+      CDBDirectory = PI->SourceRoot;
+    auto &IndexStorage = IndexStorageMap[CDBDirectory];
     if (!IndexStorage)
-      IndexStorage = create(StorageDir);
+      IndexStorage = create(CDBDirectory);
     return IndexStorage.get();
   }
 
@@ -132,7 +132,7 @@ private:
     return std::make_unique<DiskBackedIndexStorage>(CDBDirectory);
   }
 
-  Path FallbackDir;
+  Path HomeDir;
 
   llvm::StringMap<std::unique_ptr<BackgroundIndexStorage>> IndexStorageMap;
   std::unique_ptr<std::mutex> IndexStorageMapMu;

llvm/include/llvm/Support/Path.h

@@ -368,13 +368,6 @@ void system_temp_directory(bool erasedOnReboot, SmallVectorImpl<char> &result);
 /// @result True if a home directory is set, false otherwise.
 bool home_directory(SmallVectorImpl<char> &result);
 
-/// Get the directory where installed packages should put their
-/// machine-local cache, e.g. $XDG_CACHE_HOME.
-///
-/// @param result Holds the resulting path name.
-/// @result True if the appropriate path was determined, it need not exist.
-bool cache_directory(SmallVectorImpl<char> &result);
-
 /// Has root name?
 ///
 /// root_name != ""

llvm/lib/Support/Unix/Path.inc

@@ -1138,19 +1138,6 @@ bool home_directory(SmallVectorImpl<char> &result) {
   return true;
 }
 
-bool cache_directory(SmallVectorImpl<char> &result) {
-  if (const char *RequestedDir = getenv("XDG_CACHE_HOME")) {
-    result.clear();
-    result.append(RequestedDir, RequestedDir + strlen(RequestedDir));
-    return true;
-  }
-  if (!home_directory(result)) {
-    return false;
-  }
-  append(result, ".cache");
-  return true;
-}
-
 static bool getDarwinConfDir(bool TempDir, SmallVectorImpl<char> &Result) {
   #if defined(_CS_DARWIN_USER_TEMP_DIR) && defined(_CS_DARWIN_USER_CACHE_DIR)
   // On Darwin, use DARWIN_USER_TEMP_DIR or DARWIN_USER_CACHE_DIR.

llvm/lib/Support/Windows/Path.inc

@@ -1372,10 +1372,6 @@ bool home_directory(SmallVectorImpl<char> &result) {
   return getKnownFolderPath(FOLDERID_Profile, result);
 }
 
-bool cache_directory(SmallVectorImpl<char> &result) {
-  return getKnownFolderPath(FOLDERID_LocalAppData, result);
-}
-
 static bool getTempDirEnvVar(const wchar_t *Var, SmallVectorImpl<char> &Res) {
   SmallVector<wchar_t, 1024> Buf;
   size_t Size = 1024;

llvm/unittests/Support/Path.cpp

@@ -13,7 +13,6 @@
 #include "llvm/ADT/Triple.h"
 #include "llvm/BinaryFormat/Magic.h"
 #include "llvm/Config/llvm-config.h"
-#include "llvm/Support/Compiler.h"
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/Errc.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -306,46 +305,15 @@ TEST(Support, AbsolutePathIteratorEnd) {
   }
 }
 
-#ifdef _WIN32
-std::string getEnvWin(const wchar_t *Var) {
+TEST(Support, HomeDirectory) {
   std::string expected;
-  if (wchar_t const *path = ::_wgetenv(Var)) {
+#ifdef _WIN32
+  if (wchar_t const *path = ::_wgetenv(L"USERPROFILE")) {
     auto pathLen = ::wcslen(path);
     ArrayRef<char> ref{reinterpret_cast<char const *>(path),
                        pathLen * sizeof(wchar_t)};
     convertUTF16ToUTF8String(ref, expected);
   }
-  return expected;
-}
-#else
-// RAII helper to set and restore an environment variable.
-class WithEnv {
-  const char *Var;
-  llvm::Optional<std::string> OriginalValue;
-
-public:
-  WithEnv(const char *Var, const char *Value) : Var(Var) {
-    if (const char *V = ::getenv(Var))
-      OriginalValue.emplace(V);
-    if (Value)
-      ::setenv(Var, Value, 1);
-    else
-      ::unsetenv(Var);
-    set(Value);
-  }
-  ~WithEnv() {
-    if (OriginalValue)
-      ::setenv(Var, OriginalValue->c_str(), 1);
-    else
-      ::unsetenv(Var);
-  }
-};
-#endif
-
-TEST(Support, HomeDirectory) {
-  std::string expected;
-#ifdef _WIN32
-  expected = getEnvWin(L"USERPROFILE");
 #else
   if (char const *path = ::getenv("HOME"))
     expected = path;
@@ -362,48 +330,31 @@ TEST(Support, HomeDirectory) {
 
 #ifdef LLVM_ON_UNIX
 TEST(Support, HomeDirectoryWithNoEnv) {
-  WithEnv Env("HOME", nullptr);
+  std::string OriginalStorage;
+  char const *OriginalEnv = ::getenv("HOME");
+  if (OriginalEnv) {
+    // We're going to unset it, so make a copy and save a pointer to the copy
+    // so that we can reset it at the end of the test.
+    OriginalStorage = OriginalEnv;
+    OriginalEnv = OriginalStorage.c_str();
+  }
 
   // Don't run the test if we have nothing to compare against.
   struct passwd *pw = getpwuid(getuid());
   if (!pw || !pw->pw_dir) return;
+
+  ::unsetenv("HOME");
+  EXPECT_EQ(nullptr, ::getenv("HOME"));
   std::string PwDir = pw->pw_dir;
 
   SmallString<128> HomeDir;
-  EXPECT_TRUE(path::home_directory(HomeDir));
+  auto status = path::home_directory(HomeDir);
+  EXPECT_TRUE(status);
   EXPECT_EQ(PwDir, HomeDir);
-}
 
-TEST(Support, CacheDirectoryWithEnv) {
-  WithEnv Env("XDG_CACHE_HOME", "/xdg/cache");
-
-  SmallString<128> CacheDir;
-  EXPECT_TRUE(path::cache_directory(CacheDir));
-  EXPECT_EQ("/xdg/cache", CacheDir);
-}
-
-TEST(Support, CacheDirectoryNoEnv) {
-  WithEnv Env("XDG_CACHE_HOME", nullptr);
-
-  SmallString<128> Fallback;
-  ASSERT_TRUE(path::home_directory(Fallback));
-  path::append(Fallback, ".cache");
-
-  SmallString<128> CacheDir;
-  EXPECT_TRUE(path::cache_directory(CacheDir));
-  EXPECT_EQ(Fallback, CacheDir);
-}
-#endif
-
-#ifdef _WIN32
-TEST(Support, CacheDirectory) {
-  std::string Expected = getEnvWin(L"LOCALAPPDATA");
-  // Do not try to test it if we don't know what to expect.
-  if (!Expected.empty()) {
-    SmallString<128> CacheDir;
-    EXPECT_TRUE(path::cache_directory(CacheDir));
-    EXPECT_EQ(Expected, CacheDir);
-  }
+  // Now put the environment back to its original state (meaning that if it was
+  // unset before, we don't reset it).
+  if (OriginalEnv) ::setenv("HOME", OriginalEnv, 1);
 }
 #endif