cupsCheckDestSupported() does not work as expected when value = NULL

[NilanjanaLodh]

CUPS version: latest snapshot of repo
The CupsPM states that

If the value argument is NULL, the cupsCheckDestSupported function returns whether the option is supported by the destination. Otherwise, the function returns whether the specified value of the option is supported.

However, this is not working as expected for me. For instance,
cupsCheckDestSupported(http, dest, dinfo, CUPS_COPIES , NULL) returns 0;
But
cupsCheckDestSupported(http, dest, dinfo, CUPS_COPIES , "1" ) returns 1.

Also, cupsFindDestSupported(http, dest, dinfo, "job-creation-attributes") lists "copies" as one of the values.

Shouldn't cupsCheckDestSupported(http, dest, dinfo, CUPS_COPIES , NULL) have returned 1 according to the CUPS PM ?
Am I missing something in the CUPS Manual?

[michaelrsweet]

Will investigate; the API should definitely work as documented.

[michaelrsweet]

[master 49b6c6a] The cupsCheckDestSupported function did not support NULL values (Issue #5031)

[NilanjanaLodh]

I pulled the latest changes of the repo; but the problem seems to persist. 😥

[michaelrsweet]

Hmm, that should definitely not be the case. I've pushed a change to the "testdest" unit test program to verify this - after making CUPS the "testdest" program will be found in the "cups" directory, which can then be run with:

cups/testdest PRINTER-NAME supported copies

this works as expected with one printer I tested with:

cups/testdest Brother_MFC_J6920DW supported copies
copies (supported)
  1-9999