[clang] [Clang] Add #pragma clang deprecated_header (PR #168041)

[Corentin Jabot via cfe-commits]

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@@ -490,6 +490,18 @@ bool Preprocessor::HandleEndOfFile(Token &Result, bool isEndOfMacro) {
             SourceMgr.getFileEntryForID(CurPPLexer->getFileID())))
       FoundPCHThroughHeader = true;
 
+    if (CurPPLexer) {
+      if (OptionalFileEntryRef File = CurPPLexer->getFileEntry()) {
+        if (auto MaybeMessage = HeaderInfo.getHeaderDeprecationMessage(*File);
+            MaybeMessage) {
+          std::string_view Message = *MaybeMessage;
+          Diag(SourceMgr.getIncludeLoc(CurPPLexer->getFileID()),
+               diag::warn_pragma_deprecated_header)
+              << !Message.empty() << Message;
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cor3ntin wrote:

Can we avoid duplicating this code?

https://github.com/llvm/llvm-project/pull/168041