[clang-tools-extra] [include-cleaner] Make sure exports of stdlib also works for physical files (PR #72246)

[kadir çetinkaya via cfe-commits]

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@@ -232,6 +232,17 @@ class PragmaIncludes::RecordPragma : public PPCallbacks, public CommentHandler {
   void checkForExport(FileID IncludingFile, int HashLine,
                       std::optional<Header> IncludedHeader,
                       OptionalFileEntryRef IncludedFile) {
+    auto AddExport = [&] {
+      auto ExportingFileName = SM.getFileEntryForID(IncludingFile)->getName();
+      if (IncludedFile) {
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kadircet wrote:

i'd rather use the name from file entry, and get rid of `Path` stored in Top (in a follow-up change), as it's not needed anymore.

which later on should bring us 1-step closer to making `PragmaIncludes` copyable, so that clangd can easily make a copy and extend the one from Preamble build, with pragmas inside the main-file AST.

https://github.com/llvm/llvm-project/pull/72246