[llvm] [Support] Report EISDIR when opening a directory (PR #79880)

[Hubert Tong via llvm-commits]

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@@ -1296,6 +1296,29 @@ TEST_F(FileSystemTest, UTF8ToUTF16DirectoryIteration) {
 }
 #endif
 
+TEST_F(FileSystemTest, OpenDirectoryAsFileForRead) {
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hubert-reinterpretcast wrote:

> Sure, which other file would you suggest?

@azhan92, I think the idea is to leave the tests in this file but to move them within the file to be adjacent with tests that open files for read/write.

https://github.com/llvm/llvm-project/pull/79880