Ensure that the locative is singular-only unless defective

The only case in which the locative form makes sense to be given is for
words which are actually defective and only have a plural
form (e.g. Athēnae). Other than that, it makes no sense to provide
solutions like 'domibus', which have never been attested and are weird
to think about.

As a corollary, the inflection tests have been expanded with the
examples on 'Athēnae' and 'domus', so we ensure the locative behaves as
expected.

Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/lib/mihi/src/lib.rs b/lib/mihi/src/lib.rs
index 11d269a..b6abf2f 100644
--- a/lib/mihi/src/lib.rs
+++ b/lib/mihi/src/lib.rs
@@ -1779,18 +1779,26 @@ pub fn group_declension_inflections(
     let mut table = DeclensionTable::default();
 
     while let Some(row) = it.next().unwrap() {
+        let onlyplural = word.is_flag_set("onlyplural");
+
         // Fetch the number and account for defectives on number.
         let number_i: isize = row.get(1).unwrap();
         let number: usize = usize::try_from(number_i).expect("not expecting a negative number");
-        if (number == 0 && word.is_flag_set("onlyplural"))
-            || (number == 1 && word.is_flag_set("onlysingular"))
-        {
+        if (number == 0 && onlyplural) || (number == 1 && word.is_flag_set("onlysingular")) {
             continue;
         }
 
         let case_i: isize = row.get(3).unwrap();
         let term: String = row.get(4).unwrap();
 
+        // If this is the locative, on the plural, and 'onlyplural' was not
+        // specified, then chances are that the locative in the plural doesn't
+        // exist. That is because it only existed for defective nouns such as
+        // 'Athēnīs'.
+        if case_i == 6 && number == 1 && !onlyplural {
+            continue;
+        }
+
         table.add(
             word,
             usize::try_from(case_i).expect("not expecting a negative number"),