[llvm] 6399d47 - [llvm] Use the VFS to make path absolute (#161271)

[via llvm-commits]

Author: Jan Svoboda
Date: 2025-09-30T10:36:21-07:00
New Revision: 6399d4792d127520ed7281229755d18ff54da297

URL: https://github.com/llvm/llvm-project/commit/6399d4792d127520ed7281229755d18ff54da297
DIFF: https://github.com/llvm/llvm-project/commit/6399d4792d127520ed7281229755d18ff54da297.diff

LOG: [llvm] Use the VFS to make path absolute (#161271)

For the redirecting VFS, the `'overlay-relative'` option controls
whether external paths should be appended to the overlay directory. This
didn't always work as expected: when the overlay file path itself was
relative, its absolute path was decided by the real FS, not the
underlying VFS, and the resulting external path didn't exist in the
underlying VFS. This PR fixes this issue.

Added: 
    

Modified: 
    llvm/lib/Support/VirtualFileSystem.cpp
    llvm/unittests/Support/VirtualFileSystemTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Support/VirtualFileSystem.cpp b/llvm/lib/Support/VirtualFileSystem.cpp
index 7ff62d43ba205..44d2ee7076fb2 100644
--- a/llvm/lib/Support/VirtualFileSystem.cpp
+++ b/llvm/lib/Support/VirtualFileSystem.cpp
@@ -1908,7 +1908,12 @@ class llvm::vfs::RedirectingFileSystemParser {
           FullPath = FS->getOverlayFileDir();
           assert(!FullPath.empty() &&
                  "External contents prefix directory must exist");
-          llvm::sys::path::append(FullPath, Value);
+          SmallString<256> AbsFullPath = Value;
+          if (FS->makeAbsolute(FullPath, AbsFullPath)) {
+            error(N, "failed to make 'external-contents' absolute");
+            return nullptr;
+          }
+          FullPath = AbsFullPath;
         } else {
           FullPath = Value;
         }
@@ -2204,7 +2209,7 @@ RedirectingFileSystem::create(std::unique_ptr<MemoryBuffer> Buffer,
     //  FS->OverlayFileDir => /<absolute_path_to>/dummy.cache/vfs
     //
     SmallString<256> OverlayAbsDir = sys::path::parent_path(YAMLFilePath);
-    std::error_code EC = llvm::sys::fs::make_absolute(OverlayAbsDir);
+    std::error_code EC = FS->makeAbsolute(OverlayAbsDir);
     assert(!EC && "Overlay dir final path must be absolute");
     (void)EC;
     FS->setOverlayFileDir(OverlayAbsDir);

diff  --git a/llvm/unittests/Support/VirtualFileSystemTest.cpp b/llvm/unittests/Support/VirtualFileSystemTest.cpp
index d47a4ee986778..f52f25f93744d 100644
--- a/llvm/unittests/Support/VirtualFileSystemTest.cpp
+++ b/llvm/unittests/Support/VirtualFileSystemTest.cpp
@@ -1941,6 +1941,29 @@ TEST_F(VFSFromYAMLTest, ReturnsExternalPathVFSHit) {
   EXPECT_EQ(0, NumDiagnostics);
 }
 
+TEST_F(VFSFromYAMLTest, RelativeFileDirWithOverlayRelativeSetting) {
+  auto Lower = makeIntrusiveRefCnt<DummyFileSystem>();
+  Lower->addDirectory("//root/foo/bar");
+  Lower->addRegularFile("//root/foo/bar/a");
+  Lower->setCurrentWorkingDirectory("//root/foo");
+  IntrusiveRefCntPtr<vfs::FileSystem> FS =
+      getFromYAMLString("{\n"
+                        "  'case-sensitive': false,\n"
+                        "  'overlay-relative': true,\n"
+                        "  'roots': [\n"
+                        "    { 'name': '//root/foo/bar/b', 'type': 'file',\n"
+                        "      'external-contents': 'a'\n"
+                        "    }\n"
+                        "  ]\n"
+                        "}",
+                        Lower, "bar/overlay");
+
+  ASSERT_NE(FS.get(), nullptr);
+  ErrorOr<vfs::Status> S = FS->status("//root/foo/bar/b");
+  ASSERT_FALSE(S.getError());
+  EXPECT_EQ("//root/foo/bar/a", S->getName());
+}
+
 TEST_F(VFSFromYAMLTest, RootRelativeToOverlayDirTest) {
   auto Lower = makeIntrusiveRefCnt<DummyFileSystem>();
   Lower->addDirectory("//root/foo/bar");