Code review comment for lp:~vanvugt/mir/graphics-abi-is-not-libmirplatform-abi

It appears the rule is that those symbols won't exist (never emitted by the compiler) unless a class has one or more non-virtual non-default methods. Any pure virtual class (which may have some defaulted methods) will have no symbols emitted by the compiler, and don't need mentioning in symbols.map.

Certainly it's probably better maintenance practice going forward if we just add individual symbols as required (indicated by linker errors) rather than scripting the insertion of symbols that don't exist in binary. Otherwise we find ourselves in a situation I'm in now where I'm breaking a symbol that's in symbols.map, but doesn't actually exist in binary so it's no ABI break.