ctype_utf8.result, ctype_utf8.test:

  added test case
ctype-utf8.c:
  bug#11754: SET NAMES utf8 followed by SELECT "A\\" LIKE "A\\" returns 0

mysql-test/r/ctype_utf8.result

@@ -954,6 +954,45 @@ char_length(a)	length(a)	a
 2	2	12
 2	4	ан
 drop table t1;
+set names utf8;
+select 'a\\' like 'a\\';
+'a\\' like 'a\\'
+1
+select 'aa\\' like 'a%\\';
+'aa\\' like 'a%\\'
+1
+create table t1 (a char(10), key(a)) character set utf8;
+insert into t1 values ("a"),("abc"),("abcd"),("hello"),("test");
+select * from t1 where a like "abc%";
+a
+abc
+abcd
+select * from t1 where a like concat("abc","%");
+a
+abc
+abcd
+select * from t1 where a like "ABC%";
+a
+abc
+abcd
+select * from t1 where a like "test%";
+a
+test
+select * from t1 where a like "te_t";
+a
+test
+select * from t1 where a like "%a%";
+a
+a
+abc
+abcd
+select * from t1 where a like "%abcd%";
+a
+abcd
+select * from t1 where a like "%abc\d%";
+a
+abcd
+drop table t1;
 CREATE TABLE t1 (
 a varchar(255) NOT NULL default '',
 KEY a (a)

mysql-test/t/ctype_utf8.test

@@ -810,6 +810,27 @@ alter table t1 modify a char(2) character set utf8;
 select char_length(a), length(a), a from t1 order by a;
 drop table t1;
 
+
+#
+# Bugs#11754: SET NAMES utf8 followed by SELECT "A\\" LIKE "A\\" returns 0
+#
+set names utf8;
+select 'a\\' like 'a\\';
+select 'aa\\' like 'a%\\';
+
+create table t1 (a char(10), key(a)) character set utf8;
+insert into t1 values ("a"),("abc"),("abcd"),("hello"),("test");
+select * from t1 where a like "abc%";
+select * from t1 where a like concat("abc","%");
+select * from t1 where a like "ABC%";
+select * from t1 where a like "test%";
+select * from t1 where a like "te_t";
+select * from t1 where a like "%a%";
+select * from t1 where a like "%abcd%";
+select * from t1 where a like "%abc\d%";
+drop table t1;
+
+
 #
 # Bug#9557 MyISAM utf8 table crash
 #

strings/ctype-utf8.c

@@ -1557,7 +1557,7 @@ int my_wildcmp_unicode(CHARSET_INFO *cs,
       }
 
       wildstr+= scan;
-      if (w_wc ==  (my_wc_t)escape)
+      if (w_wc ==  (my_wc_t)escape && wildstr < wildend)
       {
         if ((scan= mb_wc(cs, &w_wc, (const uchar*)wildstr,
                          (const uchar*)wildend)) <= 0)
@@ -1629,13 +1629,17 @@ int my_wildcmp_unicode(CHARSET_INFO *cs,
       if ((scan= mb_wc(cs, &w_wc, (const uchar*)wildstr,
                        (const uchar*)wildend)) <=0)
         return 1;
+      wildstr+= scan;
       
       if (w_wc ==  (my_wc_t)escape)
       {
-        wildstr+= scan;
-        if ((scan= mb_wc(cs, &w_wc, (const uchar*)wildstr,
-                         (const uchar*)wildend)) <=0)
-          return 1;
+        if (wildstr < wildend)
+        {
+          if ((scan= mb_wc(cs, &w_wc, (const uchar*)wildstr,
+                           (const uchar*)wildend)) <=0)
+            return 1;
+          wildstr+= scan;
+        }
       }
       
       while (1)
@@ -1661,14 +1665,12 @@ int my_wildcmp_unicode(CHARSET_INFO *cs,
         if (str == str_end)
           return -1;
         
+        str+= scan;
         result= my_wildcmp_unicode(cs, str, str_end, wildstr, wildend,
                                    escape, w_one, w_many,
                                    weights);
-        
         if (result <= 0)
           return result;
-        
-        str+= scan;
       } 
     }
   }