The reproduction is below. Not sure if this is intended or a bug, sorry to
clutter up the mailing list if it's intended!

union __attribute__((may_alias)) works {};

// <source>:3:18: note: attribute for 'union broken2' must follow the
'union' keyword
union broken1 {} [[may_alias]];

// Okay, so let's move it so it follows union...
// <source>:7:21: warning: 'may_alias' attribute directive ignored
[-Wattributes]
//  7 | union [[may_alias]] broken2 {};
//    |                     ^~~~~~~
union [[may_alias]] broken2 {};