__ANDROID_API__ redefined after the upgrade from R20b to R23b

[little-strong666]

The compilation macro -D__ANDROID_API__=28 is defined when r20b is used.
A compilation error is reported after the upgrade to R23b.
Variable __ANDROID_API__Redefinition
Does r23b's compiler define ANDROID_API?
And what is the value of ANDROID_API?

[enh-google]

typically you'd expect the compiler to set __ANDROID_API__ --- it's been doing that since 2016 (https://reviews.llvm.org/D26385). specifically your -target aarch64-linux-android19 (or whatever) gets turned into [the equivalent of] -D__ANDROID_API__=19 (or whatever).

where that comes from will depend on what build system you're using.