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

[Jan Svoboda via cfe-commits]

================
@@ -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);
 
+struct DignosticsEngineWithCCommandLineAndDiagOpts {
+  // We need to bound the lifetime of the CCommandLine and the DiagOpts
+  // used to create the DiganosticsEngine with the DiagnosticsEngine itself.
+  std::vector<const char *> CCommandLine;
+  std::unique_ptr<DiagnosticOptions> DiagOpts;
+  IntrusiveRefCntPtr<DiagnosticsEngine> DiagEngine;
+
+  DignosticsEngineWithCCommandLineAndDiagOpts(
+      const std::vector<std::string> CommandLine,
+      IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS, DiagnosticConsumer &DC);
+};
+
+struct TextDiagnosticsPrinterWithOutput {
+  // We need to bound the lifetime of the data that supports the DiagPrinter
+  // with it together so they have the same lifetime.
+  std::string DiagnosticOutput;
+  llvm::raw_string_ostream DiagnosticsOS;
+  std::unique_ptr<DiagnosticOptions> DiagOpts;
+  TextDiagnosticPrinter DiagPrinter;
+
+  TextDiagnosticsPrinterWithOutput(const std::vector<std::string> &CommandLine)
+      : DiagnosticsOS(DiagnosticOutput),
+        DiagOpts(createDiagOptions(CommandLine)),
+        DiagPrinter(DiagnosticsOS, *DiagOpts) {}
+};
+
+std::pair<std::unique_ptr<driver::Driver>, std::unique_ptr<driver::Compilation>>
+buildCompilation(ArrayRef<std::string> ArgStrs, DiagnosticsEngine &Diags,
+                 IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS);
+
+std::unique_ptr<CompilerInvocation>
+createCompilerInvocation(const std::vector<std::string> &CommandLine,
+                         DiagnosticsEngine &Diags);
+
+std::pair<IntrusiveRefCntPtr<llvm::vfs::FileSystem>, std::vector<std::string>>
+initVFSForTUBuferScanning(IntrusiveRefCntPtr<llvm::vfs::FileSystem> BaseFS,
+                          const std::vector<std::string> &CommandLine,
+                          StringRef WorkingDirectory,
+                          llvm::MemoryBufferRef TUBuffer);
+
+std::pair<IntrusiveRefCntPtr<llvm::vfs::FileSystem>, std::vector<std::string>>
+initVFSForByNameScanning(llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> BaseFS,
----------------
jansvoboda11 wrote:

```suggestion
initVFSForByNameScanning(IntrusiveRefCntPtr<llvm::vfs::FileSystem> BaseFS,
```

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