I had supposed that the from_char_seq_search() call sites were all passing the constant arrays you'd expect them to pass ... but on looking closer, the one for DY format was passing the days array not days_short. This accidentally worked because the day abbreviations in English are all the same as the first three letters of the full day names. However, once we took out the "maximum comparison length" logic, it stopped working.
As penance for that oversight, add regression test cases covering this, as well as every other switch case in DCH_from_char() that was not reached according to the code coverage report.
Also, fold the DCH_RM and DCH_rm cases into one --- now that seq_search is case independent, there's no need to pass different comparison arrays for those cases.
Back-patch, as the previous commit was.
9a3a75cb81 Fix an oversight in commit 4c70098ff.
src/backend/utils/adt/formatting.c | 9 +----
src/test/regress/expected/horology.out | 63 ++++++++++++++++++++++++++++++++++
src/test/regress/sql/horology.sql | 19 ++++++++++
3 files changed, 83 insertions(+), 8 deletions(-)