Build Failure: Git 2.50.0-rc0 on NonStop

I encountered the following failure of rc0:

static void file_release_data(void *b REFTABLE_UNUSED, struct
reftable_block_data *dest REFTABLE_UNUSED)
                                        ^
"/home/jenkinsbuild/.jenkins/workspace/Git_Pipeline/reftable/blocksource.c",
line 105: error(112):  expected a ")"

I am not at all sure why this is failing at this point. Compiler is c99.

-- Brief whoami: NonStop&UNIX developer since approximately UNIX(421664400) NonStop(211288444200000000) -- In real life, I talk too much.