René Scharfe authored Oct 28, 2023 and Junio C Hamano committed Oct 29, 2023

Only a single PARSE_OPT_CMDMODE option can be specified for the same
variable at the same time.  This is enforced by get_value(), but the
error messages are imprecise in three ways:

1. If a non-PARSE_OPT_CMDMODE option changes the value variable of a
PARSE_OPT_CMDMODE option then an ominously vague message is shown:

   $ t/helper/test-tool parse-options --set23 --mode1
   error: option `mode1' : incompatible with something else

Worse: If the order of options is reversed then no error is reported at
all:

   $ t/helper/test-tool parse-options --mode1 --set23
   boolean: 0
   integer: 23
   magnitude: 0
   timestamp: 0
   string: (not set)
   abbrev: 7
   verbose: -1
   quiet: 0
   dry run: no
   file: (not set)

Fortunately this can currently only happen in the test helper; actual
Git commands don't share the same variable for the value of options with
and without the flag PARSE_OPT_CMDMODE.

2. If there are multiple options with the same value (synonyms),...