[clang] [clang][Dependency Scanning] Refactor Scanning Compiler Instance Initialization (PR #161300)

[Qiongsi Wu via cfe-commits]

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@@ -72,9 +74,77 @@ class DependencyScanningAction {
   bool DiagConsumerFinished = false;
 };
 
-// Helper functions
-void sanitizeDiagOpts(DiagnosticOptions &DiagOpts);
+// Helper functions and data types.
+std::unique_ptr<DiagnosticOptions>
+createDiagOptions(const std::vector<std::string> &CommandLine);
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qiongsiwu wrote:

Sounds good! I've replaced `std::vector`s with `ArrayRef`s as much as possible. 

https://github.com/llvm/llvm-project/pull/161300