[compiler-rt] [libunwind] [libunwind][cmake] Compile _Unwind* routines with -fexceptions (PR #121819)

[Petr Hosek via llvm-commits]

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@@ -20,7 +20,12 @@ set(LIBUNWIND_C_SOURCES
     )
 set_source_files_properties(${LIBUNWIND_C_SOURCES}
                             PROPERTIES
-                              COMPILE_FLAGS "-std=c99")
+                              # We need to set `-fexceptions` here so that key
+                              # unwinding functions, like
+                              # _UNWIND_RaiseExcpetion, are not marked as
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petrhosek wrote:

```suggestion
                              # _UNWIND_RaiseException, are not marked as
```

https://github.com/llvm/llvm-project/pull/121819