[clang] [Clang][LTO] Fix use of funified-lto and save-temps flags together (PR #162763)

[Paul Kirth via cfe-commits]

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@@ -0,0 +1,11 @@
+; Test that we do not duplicate the UnifiedLTO module flag.
+;
+; RUN: %clang_cc1 -emit-llvm -flto=full -funified-lto -o - %s | FileCheck %s
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ilovepi wrote:

I assume before this patch, this would crash w/ the message in the commit body?

https://github.com/llvm/llvm-project/pull/162763