[clang] Make `FileEntryRef::getDir()` return the as-requested `DirectoryEntryRef`

For redirected file entries, `FileEntryRef::getDir()` returns the parent directory entry of the target file entry. This differs from `FileEntry::getDir()` that always returns the parent directory that was last used to look up that file.

After switching from `FileEntry` to `FileEntryRef` for umbrella headers in D142113, this discrepancy became observable and caused Clang to emit incorrect diagnostics.

This patch changes Clang so that it always associates `FileEntryRef` with the parent directory that was used to look it up. This brings its behavior closer to `FileEntry`, but without the hacky mutation.

This also ensures that `llvm::sys::path::parent_path(FileRef->getNameAsRequested()) == FileRef->getDir()->getName()`. Previously, `FileRef->getDir()` would fall underneath the redirecting VFS into the world of on-disk paths.

Reviewed By: benlangmuir, rmaz

Differential Revision: https://reviews.llvm.org/D151398

1 files changed, 20 insertions, 0 deletions

diff --git a/clang/unittests/Basic/FileManagerTest.cpp b/clang/unittests/Basic/FileManagerTest.cpp
index 146a609..4c8205b 100644
--- a/clang/unittests/Basic/FileManagerTest.cpp
+++ b/clang/unittests/Basic/FileManagerTest.cpp
@@ -310,6 +310,26 @@ TEST_F(FileManagerTest, getFileRefReturnsCorrectNameForDifferentStatPath) {
   EXPECT_EQ(&F2->getFileEntry(), &F2Alias2->getFileEntry());
 }
 
+TEST_F(FileManagerTest, getFileRefReturnsCorrectDirNameForDifferentStatPath) {
+  // Inject files with the same inode into distinct directories (name & inode).
+  auto StatCache = std::make_unique<FakeStatCache>();
+  StatCache->InjectDirectory("dir1", 40);
+  StatCache->InjectDirectory("dir2", 41);
+  StatCache->InjectFile("dir1/f.cpp", 42);
+  StatCache->InjectFile("dir2/f.cpp", 42, "dir1/f.cpp");
+
+  manager.setStatCache(std::move(StatCache));
+  auto Dir1F = manager.getFileRef("dir1/f.cpp");
+  auto Dir2F = manager.getFileRef("dir2/f.cpp");
+
+  ASSERT_FALSE(!Dir1F);
+  ASSERT_FALSE(!Dir2F);
+  EXPECT_EQ("dir1", Dir1F->getDir().getName());
+  EXPECT_EQ("dir2", Dir2F->getDir().getName());
+  EXPECT_EQ("dir1/f.cpp", Dir1F->getNameAsRequested());
+  EXPECT_EQ("dir2/f.cpp", Dir2F->getNameAsRequested());
+}
+
 // getFile() returns the same FileEntry for virtual files that have
 // corresponding real files that are aliases.
 TEST_F(FileManagerTest, getFileReturnsSameFileEntryForAliasedVirtualFiles) {