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

[Michael Halkenhäuser via llvm-commits]

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

>From ba85225805b8e0b446e32b0c08ef4fb08dbebee5 Mon Sep 17 00:00:00 2001
From: Michael Halkenhaeuser <MichaelGerald.Halkenhauser at amd.com>
Date: Wed, 21 Feb 2024 11:58:17 -0600
Subject: [PATCH] [llvm-link] Improve missing file error message

Add error message showing the missing filename.

Currently, we only get 'No such file or directory' without any(!) further info.
This patch will (upon ENOENT error) create an error which exposes the filename.
---
 llvm/tools/llvm-link/llvm-link.cpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/llvm/tools/llvm-link/llvm-link.cpp b/llvm/tools/llvm-link/llvm-link.cpp
index e6c219a8cd7ece..8ae13181d5f295 100644
--- a/llvm/tools/llvm-link/llvm-link.cpp
+++ b/llvm/tools/llvm-link/llvm-link.cpp
@@ -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);
+
+    // When we encounter a missing file, make sure we expose its name.
+    if (auto EC = ErrOrExpected.getError())
+      if (EC == std::errc::no_such_file_or_directory)
+        ExitOnErr(createStringError(EC, "No such file or directory: '%s'",
+                                    File.c_str()));
+
     std::unique_ptr<MemoryBuffer> Buffer =
-        ExitOnErr(errorOrToExpected(MemoryBuffer::getFileOrSTDIN(File)));
+        ExitOnErr(errorOrToExpected(std::move(ErrOrExpected)));
 
     std::unique_ptr<Module> M =
         identify_magic(Buffer->getBuffer()) == file_magic::archive