[llvm] [clang] Fix handling of adding a file with the same name as an existing dir to VFS (PR #94461)

[via llvm-commits]

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@@ -1138,6 +1138,8 @@ TEST_F(InMemoryFileSystemTest, DuplicatedFile) {
   ASSERT_FALSE(FS.addFile("/a/b", 0, MemoryBuffer::getMemBuffer("a")));
   ASSERT_TRUE(FS.addFile("/a", 0, MemoryBuffer::getMemBuffer("a")));
   ASSERT_FALSE(FS.addFile("/a", 0, MemoryBuffer::getMemBuffer("b")));
+  ASSERT_TRUE(FS.addFile("/b/c/d", 0, MemoryBuffer::getMemBuffer("a")));
+  ASSERT_FALSE(FS.addFile("/b/c", 0, MemoryBuffer::getMemBuffer("a")));
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jensmassberg wrote:

I have added an additional test case.

https://github.com/llvm/llvm-project/pull/94461