[PATCH] D158573: [clang][modules] Move `UNHASHED_CONTROL_BLOCK` up in the AST file

[Ben Langmuir via Phabricator via cfe-commits]

benlangmuir added inline comments.


================
Comment at: clang/lib/Serialization/ASTWriter.cpp:1169
+      writeSignature(Sig, Out);
+      std::copy_n(Out.begin(), Out.size(), Buffer.begin() + Offset);
+    };
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jansvoboda11 wrote:
> I don't feel great about removing `const` from `Buffer` and writing into it directly, circumventing `Stream`. This currently works fine, because the `Stream` in `ASTWriter` is never backed by a file (and therefore never flushed). But if that ever changes, this code is problematic. Do you think this is worth spending more time on?
> 
> `Stream` already has the `BackpatchWord()` function, which makes sure the underlying file is updated as well in case we're backpatching already-flushed data.
Interesting; what was the reason for not using BackpatchWord from the start? IIUC our signatures should be a multiple of 4 bytes already.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D158573/new/

https://reviews.llvm.org/D158573