JNI: treat enums as their underlying types

Android APIs use integer constants like enum values, so they are mapped
to one of the integeral types (jint, jshort, jlong etc) on the C++ side.
Enable C++ code to declare an equivalent enum (scoped or unscoped), and
to use that enum as a type in JNI calls by treating it as the underlying
type in the signature() generator.

Add a helper type trait that maps enums to their underlying type and
other integral types to themselves (we can't use std::underlying_type_t
on a non-enum type). Add tests.

Note: Java Enums are special classes with fields; this change does not
add any special support for those.

Change-Id: Iec430a1553152dcf7a24209aaebbeceb1c6e38a8
Reviewed-by: Petri Virkkunen <[email protected]>
Reviewed-by: Zoltan Gera <[email protected]>
Reviewed-by: Juha Vuolle <[email protected]>

0 files changed, 0 insertions, 0 deletions