[FR] improve bad diagnostic for __REMOVED_IN on ALooper_pollAll

[DanAlbert]

Description

error: 'ALooper_pollAll' is unavailable: obsoleted in Android 1
     45 |     if (ALooper_pollAll(IsVulkanReady() ? 1 : 0, nullptr,
        |         ^
  usr/include/android/looper.h:216:5: note: 'ALooper_pollAll' has been explicitly marked unavailable here
    216 | int ALooper_pollAll(int timeoutMillis, int* outFd, int* outEvents, void** outData) __REMOVED_IN(1);
        |     ^

It's been marked obsolete because the implementation is racy and can't be called safely, but ALooper_pollOnce can be called in a loop for the same effect, and is available for all supported OS versions.

The diagnostic is next to useless though, and should be expanded to include that explanation.

I've explained the OS bug in another thread to not bog down this bug (which is about an unclear diagnostic, not a missing API): #2020.

[enh-google]

is plain old __attribute__((__deprecated__(("use foo instead")))) a better choice then, since it includes a user-provided diagnostic?

[DanAlbert]

__attribute__((availability)) supports that too. We don't expose that in __REMOVED_IN() though, and that's the fix we need.

[enh-google]

oh, yeah, that seems like a bug in __REMOVED_IN() --- i vote we require an explanation...

[DanAlbert]

Don't know why I didn't think of that, or why we didn't do that in the first place :) +1