master f2019fc: Fix case-insensitive completion of buffer names

[Eli Zaretskii]

branch: master
commit f2019fc676c2206bbdc53855e3bc4f1086676d3d
Author: Eli Zaretskii <address@hidden>
Commit: Eli Zaretskii <address@hidden>

    Fix case-insensitive completion of buffer names
    
    * test/src/minibuf-tests.el (test-try-completion-ignore-case):
    New test, suggested by Stefan Monnier <address@hidden>.
    
    * src/minibuf.c (Ftry_completion): Don't treat strings that
    are identical but for the case as if they were identical for
    the purposes of not counting the same string twice.  This
    fixes case-insensitive completion when all the candidates are
    identical but for the letter-case.  (Bug#11339)
---
 src/minibuf.c             | 15 ++++++++++-----
 test/src/minibuf-tests.el | 11 +++++++++++
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/src/minibuf.c b/src/minibuf.c
index f6cf47f..1e87c50 100644
--- a/src/minibuf.c
+++ b/src/minibuf.c
@@ -1323,13 +1323,13 @@ is used to further constrain the set of candidates.  */)
          else
            {
              compare = min (bestmatchsize, SCHARS (eltstring));
-             tem = Fcompare_strings (bestmatch, zero,
-                                     make_fixnum (compare),
-                                     eltstring, zero,
-                                     make_fixnum (compare),
+             Lisp_Object lcompare = make_fixnum (compare);
+             tem = Fcompare_strings (bestmatch, zero, lcompare,
+                                     eltstring, zero, lcompare,
                                      completion_ignore_case ? Qt : Qnil);
              matchsize = EQ (tem, Qt) ? compare : eabs (XFIXNUM (tem)) - 1;
 
+             Lisp_Object old_bestmatch = bestmatch;
              if (completion_ignore_case)
                {
                  /* If this is an exact match except for case,
@@ -1363,7 +1363,12 @@ is used to further constrain the set of candidates.  */)
                    bestmatch = eltstring;
                }
              if (bestmatchsize != SCHARS (eltstring)
-                 || bestmatchsize != matchsize)
+                 || bestmatchsize != matchsize
+                 || (completion_ignore_case
+                     && !EQ (Fcompare_strings (old_bestmatch, zero, lcompare,
+                                               eltstring, zero, lcompare,
+                                               Qnil),
+                             Qt)))
                /* Don't count the same string multiple times.  */
                matchcount += matchcount <= 1;
              bestmatchsize = matchsize;
diff --git a/test/src/minibuf-tests.el b/test/src/minibuf-tests.el
index 12b018b..c648928 100644
--- a/test/src/minibuf-tests.el
+++ b/test/src/minibuf-tests.el
@@ -399,5 +399,16 @@
   (minibuf-tests--test-completion-regexp
    #'minibuf-tests--strings-to-symbol-hashtable))
 
+(ert-deftest test-try-completion-ignore-case ()
+  (let ((completion-ignore-case t))
+    (should (equal (try-completion "bar" '("bAr" "barfoo")) "bAr"))
+    (should (equal (try-completion "bar" '("bArfoo" "barbaz")) "bar"))
+    (should (equal (try-completion "bar" '("bArfoo" "barbaz"))
+                   (try-completion "bar" '("barbaz" "bArfoo"))))
+    ;; bug#11339
+    (should (equal (try-completion "baz" '("baz" "bAz")) "baz")) ;And not `t'!
+    (should (equal (try-completion "baz" '("bAz" "baz"))
+                   (try-completion "baz" '("baz" "bAz"))))))
+
 
 ;;; minibuf-tests.el ends here