struct member updated to union generates false-positive incompatibility

[dkogan]

Hi. I'm comparing the API/ABI of a library that had

struct { int x; };

To one that has

struct { union {int x,y}; };

This should be a backwards-compatible change: the old sources can still refer to element 'x' by name and get the right thing. But abi-compliance checker sees this as a rename from 'x' to 'unnamed0', and flags it as an incompatibility.