casing: don’t assume letters are *either* upper- or lower-case (bug#24603)

A compatibility digraph characters, such as Dž, are neither upper- nor
lower-case.  At the moment however, those are reported as upper-case¹
despite the fact that they change when upper-cased.

Stop checking if a character is upper-case before trying to up-case it
so that title-case characters are handled correctly.  This fixes one of
the issues mentioned in bug#24603.

¹ Because they change when converted to lower-case.  Notice an asymmetry
  in that for a character to be considered lower-case it must not be
  upper-case (plus the usual condition of changing when upper-cased).

* src/buffer.h (upcase1): Delete.
(upcase): Change to upcase character unconditionally just like downcase
does it.  This is what upcase1 was.

* src/casefiddle.c (casify_object, casify_region): Use upcase instead
of upcase1 and don’t check !uppercasep(x) before calling upcase.

* src/keyboard.c (read_key_sequence): Don’t check if uppercase(x), just
downcase(x) and see if it changed.

* test/src/casefiddle-tests.el (casefiddle-tests--characters,
casefiddle-tests-casing): Update test cases which are now passing.

1 files changed, 4 insertions, 4 deletions

diff --git a/test/src/casefiddle-tests.el b/test/src/casefiddle-tests.el
index c752bb09172..152d85de006 100644
--- a/test/src/casefiddle-tests.el
+++ b/test/src/casefiddle-tests.el
@@ -63,13 +63,13 @@
     (?Ł ?Ł ?ł ?Ł)
     (?ł ?Ł ?ł ?Ł)
 
-    ;; FIXME(bug#24603): We should have:
+    ;; FIXME(bug#24603): Commented ones are what we want.
     ;;(?DŽ ?DŽ ?dž ?Dž)
-    ;; but instead we have:
     (?DŽ ?DŽ ?dž ?DŽ)
-    ;; FIXME(bug#24603): Those two are broken at the moment:
     ;;(?Dž ?DŽ ?dž ?Dž)
+    (?Dž ?DŽ ?dž ?DŽ)
     ;;(?dž ?DŽ ?dž ?Dž)
+    (?dž ?DŽ ?dž ?DŽ)
 
     (?Σ ?Σ ?σ ?Σ)
     (?σ ?Σ ?σ ?Σ)
@@ -197,7 +197,7 @@
         ;;("ΌΣΟΣ" "ΌΣΟΣ" "όσος" "Όσος" "Όσος")
         ;; And here’s what is actually happening:
         ("DŽUNGLA" "DŽUNGLA" "džungla" "DŽungla" "DŽUNGLA")
-        ("Džungla" "��UNGLA" "džungla" "��ungla" "��ungla")
+        ("Džungla" "��UNGLA" "džungla" "��ungla" "��ungla")
         ("džungla" "DŽUNGLA" "džungla" "DŽungla" "DŽungla")
         ("define" "DEfiNE" "define" "Define" "Define")
         ("fish" "fiSH" "fish" "fish" "fish")