[llvm] Give a warning when no dwo files are provided (PR #94336)

[Alexander Yermolovich via llvm-commits]

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@@ -0,0 +1,9 @@
+; RUN: rm -rf %t && mkdir -p %t && split-file %s %t && cd %t
+; RUN: clang -g -gdwarf-4 %t/non_split.c -o %t/non_split.o
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ayermolo wrote:

oh didn't know that.
Why did the test pass? Thought there would be an error "clang not found" or something like that.

https://github.com/llvm/llvm-project/pull/94336