LOCAL_CFLAGS do not disable warnings in Clang

[alexcohn]

Description

Switching to Clang from GCC in r14, we have a problem with compilation of some 3^rd party libraries, e.g. gumbo-query. See google/gumbo-parser#377 for details.

The problem specific to NDK is that when we switch to Clang, we cannot silence the warnings by tuning LOCAL_CFLAGS for the specific library the way we used to, with GCC. The reason is that when I turn on the warnings with APP_CFLAGS+=-Wall, this goes after the LOCAL_CFLAGS, and with Clang, -Wall overrides -Wno-unused-variable.

Environment Details

• NDK Version: 14.0.3675639-beta2
• Build sytem: ndk-build
• Host OS: Mac
• Compiler: Clang
• ABI: checked with x86, but is probably relevant to the others.

[DanAlbert]

Is this actually unique to r14?

[alexcohn]

I believe it is Clang-specific, we never tried to switch from gcc before.

…

On Thu, Mar 2, 2017 at 19:25 Dan Albert ***@***.***> wrote: Is this actually unique to r14? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#307 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAs8s-eOBwyMcK-_7pBG-Xf2yT8AnnYnks5rhvtrgaJpZM4MRByU> .

[DanAlbert]

https://android-review.googlesource.com/356722

[DanAlbert]

Merged into master and I've cherry-picked to r15. It probably won't be in r15 beta 1, but if I need to respin that yet again it will be.

[DanAlbert]

FYI, I sent an email to one of the owners of the gumbo lib to see if we can get those warnings fixed rather than just suppressed.

[alexcohn]

Cool, I did not see reaction from gumbo on my request, and the pull request that fixes this specific warning is pending since Oct 2015.

But gumbo is definitely not the only/last library on GitHub that compiles with warnings in Clang, or will compile with warnings in the next version of Clang. That's why a fix for Clang or NDK is required.

I believe that it is very important to encourage use of -Wall in APP_CFLAGS.

[DanAlbert]

Turns out we are respinning beta 1, so I've cherry-picked this. Should be available some time next week.

[enh]

fix now available in r15beta1...