[Build] Disable -Wdocumentation

[bnbarham]

LLVM doesn't have this warning enabled, so we end up with a whole tonne of warnings from the LLVM headers.

[bnbarham]

@swift-ci please smoke test

[compnerd]

I'm fine with removing it, but I do wonder why this was enabled in the first place.

[bnbarham]

I'm fine with removing it, but I do wonder why this was enabled in the first place.

@akyrtzi seems like you added this back in 2013 (bf25dde). How do you feel about it being removed? The only real alternative I can think of would be to have all our LLVM include paths as system, though I suspect that would have unintended side effects.

Otherwise there's the whack-a-mole game we could play with fixing upstream as these come in. Or a RFC to try get it enabled generally.

[tshortli]

Thank you! These warnings have been polluting the Swift build quite a bit, and I don't think there's a point in having them if LLVM is not also going to be built with the flag to prevent the problems from occurring upstream.

[akyrtzi]

@akyrtzi seems like you added this back in 2013 (bf25dde). How do you feel about it being removed?

I assume I added it because LLVM had it enabled then, if LLVM doesn't have it enabled then I agree to remove it.

Interestingly, I see upstream commits about fixing -Wdocumentation warnings, not sure how people discover them if it's not enabled.

[bnbarham]

Interestingly, I see upstream commits about fixing -Wdocumentation warnings, not sure how people discover them if it's not enabled.

Might have it locally like we do 😅? I definitely don't see a -Wdocumentation in LLVM, unless it's enabled by default with some other warning.

[tshortli]

Might have it locally like we do 😅? I definitely don't see a -Wdocumentation in LLVM, unless it's enabled by default with some other warning.

They're all from Apple folks, so I suspect the problems are just being noticed downstream and fixed upstream to quite builds.