const_defconst_init matched MakeCase at the top level only, so a case nested in
a struct literal got the general computed message, whose advice nobody could
follow. Emit.const found it by recursing; this finds it the same way, left to
right and first offender wins, which is the order the emitter spelled fields
in. FIX.org's claim that the messages did not change is rewritten to say what
did change about the general one.