[clang] [C++20] [Modules] Offer -fmodules-embed-all-files option (PR #107194)

[Erich Keane via cfe-commits]

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@@ -484,6 +511,13 @@ fragment is disabled by default. These checks can be enabled by specifying
 and you encounter incorrect or missing diagnostics, please report them via the
 `community issue tracker <https://github.com/llvm/llvm-project/issues/>`_.
 
+Privacy Issue
+-------------
+
+BMIs are not and should not be treated as an information hiding mechanism.
+They should always be assumed to contain all the information that was used to
+create them, in a recoverable form.
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erichkeane wrote:

I might expand on this a bit with something like, "While the `-fmodules_embed_all_files` flag explicitly emits the source code into the BMI file, the contents of the BMI file contain a sufficiently verbose(word choice?) representation to reproduce the original source file."

I'd like to make this warning as clear as possible: If you ship a BMI, you mind as well just ship the source code.

https://github.com/llvm/llvm-project/pull/107194