[flang] [clang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Kiran Chandramohan via cfe-commits]

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@@ -0,0 +1,15 @@
+! UNSUPPORTED: system-windows
+
+! RUN: %clang -o %t.c-object -c %S/Inputs/main_dupes.c
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kiranchandramohan wrote:

You can use %cc for the system-compiler and REQUIRE it to be present for this test. 
Reference: https://github.com/llvm/llvm-project/blob/main/flang/test/Runtime/no-cpp-dep.c

https://github.com/llvm/llvm-project/pull/73124