[clang] [WIP] Implement `print-deserialized-declarations` flag to dump source… (PR #133910)

[Ilya Biryukov via cfe-commits]

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@@ -121,6 +252,19 @@ FrontendAction::CreateWrappedASTConsumer(CompilerInstance &CI,
   if (!Consumer)
     return nullptr;
 
+  std::vector<std::unique_ptr<ASTConsumer>> Consumers;
+  llvm::StringRef PrintDeserializedDeclarationsPath = CI.getFrontendOpts().PrintDeserializedDeclarationsPath;
+  if (!PrintDeserializedDeclarationsPath.empty()) {
+    std::error_code ErrorCode;
+    auto* FileStream = new llvm::raw_fd_ostream(PrintDeserializedDeclarationsPath, ErrorCode, llvm::sys::fs::OF_None);
+    if (!ErrorCode) {
+      DeserializedDeclsLineRangePrinter* Printer = new DeserializedDeclsLineRangePrinter(CI.getSourceManager(), std::unique_ptr<llvm::raw_fd_ostream>(FileStream));
+      Consumers.push_back(std::unique_ptr<ASTConsumer>(Printer));
+    } else {
+      llvm::errs() << "Could not open file with path: " << PrintDeserializedDeclarationsPath << ", error: " << ErrorCode.message() << "\n";
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ilya-biryukov wrote:

NIT: maybe add a more descriptive error message, e.g. `Failed to create output file for -<flag>`?

https://github.com/llvm/llvm-project/pull/133910