[PATCH] D75655: [Docs] Document -lto-whole-program-visibility

[Peter Collingbourne via Phabricator via cfe-commits]

pcc added a comment.

I think that the part of the description beginning "This can be used when..." is somewhat misleading since you could pretty much say the same thing about specifying `-fvisibility=hidden -fwhole-program-vtables` at compile time.

I think it would be better to focus on the specific capability that `--lto-visibility-hidden` gives you over just compiling with `-fvisibility=hidden`. Let's keep @evgeny777 's use case out of this because I still have concerns about it being dangerous. Can you simply say:

"This flag can be used to defer specifying whether classes have hidden LTO visibility until link time."

Then, in order to try to forbid inappropriate use of the symbols, you could add:

"Due to an implementation limitation, symbols associated with classes with hidden LTO visibility may still be exported from the binary when using this flag. It is unsafe to refer to these symbols, and their visibility may be relaxed to hidden in a future compiler release."


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https://reviews.llvm.org/D75655