[clang] 7548ad0 - clang: normalise directory cache keys consistently in `FileManager` (#181306)

[via cfe-commits]

Author: Saleem Abdulrasool
Date: 2026-02-18T13:58:38-08:00
New Revision: 7548ad01ab17a6892264032b19cf19be1d182bea

URL: https://github.com/llvm/llvm-project/commit/7548ad01ab17a6892264032b19cf19be1d182bea
DIFF: https://github.com/llvm/llvm-project/commit/7548ad01ab17a6892264032b19cf19be1d182bea.diff

LOG: clang: normalise directory cache keys consistently in `FileManager` (#181306)

Extract the directory path normalisation logic into a shared
`normalizeCacheKey` helper and apply it in `addAncestorsAsVirtualDirs`
in addition to `getDirectoryRef`. This ensures that cache lookups and
insertions use a consistent key at all call sites.

Co-authored-by: Corentin Jabot <corentinjabot at gmail.com>

Added: 
    

Modified: 
    clang/lib/Basic/FileManager.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Basic/FileManager.cpp b/clang/lib/Basic/FileManager.cpp
index 6d6ea5b84369b..44092efd74717 100644
--- a/clang/lib/Basic/FileManager.cpp
+++ b/clang/lib/Basic/FileManager.cpp
@@ -38,6 +38,27 @@ using namespace clang;
 
 #define DEBUG_TYPE "file-search"
 
+static void normalizeCacheKey(StringRef &Path,
+                              std::optional<std::string> &Storage) {
+  using namespace llvm::sys::path;
+
+  // Drop trailing separators for non-root paths so that cache keys and `stat`
+  // queries use a single spelling. Keep root paths (`/`, `[A-Z]:\`) unchanged.
+  if (Path.size() > 1 && root_path(Path) != Path && is_separator(Path.back()))
+    Path = Path.drop_back();
+
+  // A bare drive path like "[A-Z]:" is drive-relative (current directory on the
+  // drive).  As `[A-Z]:` is not a path specification, we must canonicalise it
+  // to `[A-Z]:.`.
+  if (is_style_windows(Style::native)) {
+    if (Path.size() > 1 && Path.back() == ':' &&
+        Path.equals_insensitive(root_name(Path))) {
+      Storage = Path.str() + ".";
+      Path = *Storage;
+    }
+  }
+}
+
 //===----------------------------------------------------------------------===//
 // Common logic.
 //===----------------------------------------------------------------------===//
@@ -104,6 +125,13 @@ void FileManager::addAncestorsAsVirtualDirs(StringRef Path) {
   if (DirName.empty())
     DirName = ".";
 
+  // Normalize the key for cache lookup/insert, but keep the original DirName
+  // for recursive processing since normalization can create paths that don't
+  // work well with parent_path() (e.g., "C:" -> "C:.").
+  std::optional<std::string> Storage;
+  StringRef OriginalDirName = DirName;
+  normalizeCacheKey(DirName, Storage);
+
   auto &NamedDirEnt = *SeenDirEntries.insert(
         {DirName, std::errc::no_such_file_or_directory}).first;
 
@@ -131,28 +159,13 @@ void FileManager::addAncestorsAsVirtualDirs(StringRef Path) {
   }
 
   // Recursively add the other ancestors.
-  addAncestorsAsVirtualDirs(DirName);
+  addAncestorsAsVirtualDirs(OriginalDirName);
 }
 
 llvm::Expected<DirectoryEntryRef>
 FileManager::getDirectoryRef(StringRef DirName, bool CacheFailure) {
-  // stat doesn't like trailing separators except for root directory.
-  // At least, on Win32 MSVCRT, stat() cannot strip trailing '/'.
-  // (though it can strip '\\')
-  if (DirName.size() > 1 &&
-      DirName != llvm::sys::path::root_path(DirName) &&
-      llvm::sys::path::is_separator(DirName.back()))
-    DirName = DirName.drop_back();
   std::optional<std::string> DirNameStr;
-  if (is_style_windows(llvm::sys::path::Style::native)) {
-    // Fixing a problem with "clang C:test.c" on Windows.
-    // Stat("C:") does not recognize "C:" as a valid directory
-    if (DirName.size() > 1 && DirName.back() == ':' &&
-        DirName.equals_insensitive(llvm::sys::path::root_name(DirName))) {
-      DirNameStr = DirName.str() + '.';
-      DirName = *DirNameStr;
-    }
-  }
+  normalizeCacheKey(DirName, DirNameStr);
 
   ++NumDirLookups;