[clang] cc1: Report an error for multiple actions unless separated by -main-file-name (PR #91140)

[Fangrui Song via cfe-commits]

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@@ -134,6 +134,8 @@ def err_fe_no_pch_in_dir : Error<
     "no suitable precompiled header file found in directory '%0'">;
 def err_fe_action_not_available : Error<
     "action %0 not compiled in">;
+def err_fe_invalid_multiple_actions : Error<
+    "action %0 is specified, another action is not allowed: %1">;
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MaskRay wrote:

Thanks for the suggestion. I adopted it by swapping %1 and %0 ...

https://github.com/llvm/llvm-project/pull/91140