textiter: bug fix in forward_search() and backward_search()

When the search is case sensitive, g_utf8_normalize() is not called, so
the skip_decomp argument of the function forward_chars_with_skipping()
must be FALSE.

To verify that, when searching "éb", the count parameter of
forward_chars_with_skipping() have a different value:
- case sensitive: count = 2
- case insensitive: count = 3 (g_utf8_normalize() has been called)

The commit adds unit tests that didn't pass before, and that now pass
(without known regression, obviously).

https://bugzilla.gnome.org/show_bug.cgi?id=702977

gtk/gtktextiter.c

@@ -4409,7 +4409,6 @@ forward_chars_with_skipping (GtkTextIter *iter,
                              gboolean     skip_nontext,
                              gboolean     skip_decomp)
 {
-
   gint i;
 
   g_return_if_fail (count >= 0);
@@ -4421,8 +4420,8 @@ forward_chars_with_skipping (GtkTextIter *iter,
       gboolean ignored = FALSE;
 
       /* minimal workaround to avoid the infinite loop of bug #168247. */
-       if (gtk_text_iter_is_end (iter))
+      if (gtk_text_iter_is_end (iter))
-         return;
+        return;
 
       if (skip_nontext &&
           gtk_text_iter_get_char (iter) == GTK_TEXT_UNKNOWN_CHAR)
@@ -4749,7 +4748,7 @@ lines_match (const GtkTextIter *start,
 
   /* Go to end of search string */
   forward_chars_with_skipping (&next, g_utf8_strlen (*lines, -1),
-                               visible_only, !slice, TRUE);
+                               visible_only, !slice, case_insensitive);
 
   g_free (line_text);
 
@@ -5307,7 +5306,7 @@ gtk_text_iter_backward_search (const GtkTextIter *iter,
             }
 
           forward_chars_with_skipping (&next, offset,
-                                       visible_only, !slice, TRUE);
+                                       visible_only, !slice, case_insensitive);
 
           if (match_end)
             *match_end = next;

testsuite/gtk/textiter.c

@@ -174,6 +174,18 @@ test_search (void)
   check_found_forward ("This is some foo\nfoo text", "foo\nfoo", 0, 13, 20, "foo\nfoo");
   check_found_backward ("This is some foo\nfoo text", "foo\nfoo", 0, 13, 20, "foo\nfoo");
   check_not_found ("This is some foo\nfoo text", "Foo\nfoo", 0);
+
+  /* check also that different composition of utf8 characters
+     (e.g. accented letters) match */
+
+  check_found_forward ("This is some \303\200 text", "\303\200", 0, 13, 14, "\303\200");
+  check_found_forward ("This is some \303\200 text", "some \303\200", 0, 8, 14, "some \303\200");
+  check_found_forward ("This is some \303\200 text", "\303\200 text", 0, 13, 19, "\303\200 text");
+  check_found_forward ("This is some \303\200 text", "some \303\200 text", 0, 8, 19, "some \303\200 text");
+  check_found_backward ("This is some \303\240 text", "\303\240", 0, 13, 14, "\303\240");
+  check_found_backward ("This is some \303\240 text", "some \303\240", 0, 8, 14, "some \303\240");
+  check_found_backward ("This is some \303\240 text", "\303\240 text", 0, 13, 19, "\303\240 text");
+  check_found_backward ("This is some \303\240 text", "some \303\240 text", 0, 8, 19, "some \303\240 text");
 }
 
 static void