FileError: Support zero-length file names

It's a common error in an API - to try to open an empty file, so it
seems like a reasonable FileError to produce "hey, you tried to open an
empty file" and to handle it the same way as any other file error.

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/unittests/Support/ErrorTest.cpp b/llvm/unittests/Support/ErrorTest.cpp
index d9e86fdd..9356402 100644
--- a/llvm/unittests/Support/ErrorTest.cpp
+++ b/llvm/unittests/Support/ErrorTest.cpp
@@ -957,6 +957,9 @@ TEST(Error, FileErrorTest) {
                 .compare("'file.bin': CustomError {41}\n"
                          "'file2.bin': CustomError {42}"),
             0);
+
+  Error FE5 = createFileError("", make_error<CustomError>(1));
+  EXPECT_EQ(toString(std::move(FE5)).compare("'': CustomError {1}"), 0);
 }
 
 enum class test_error_code {