[llvm] [llvm-link] Improve missing file error message (PR #82514)

[Joseph Huber via llvm-commits]

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@@ -393,8 +393,16 @@ static bool linkFiles(const char *argv0, LLVMContext &Context, Linker &L,
   // Similar to some flags, internalization doesn't apply to the first file.
   bool InternalizeLinkedSymbols = false;
   for (const auto &File : Files) {
+    auto ErrOrExpected = MemoryBuffer::getFileOrSTDIN(File);
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jhuber6 wrote:

Nit, this filename is a little weird, maybe `BufferOrErr`?

https://github.com/llvm/llvm-project/pull/82514