[gnumeric] Conditional Style: fix crash.

[Morten Welinder <mortenw src gnome org>]

commit 052c1b11c5177a34ea0e4ccd793fbaa9dba4073e
Author: Morten Welinder <terra gnome org>
Date:   Wed Jan 19 17:22:40 2022 -0500

    Conditional Style: fix crash.
    
    See #597.

 ChangeLog    |  5 +++++
 NEWS         |  1 +
 src/mstyle.c | 20 ++++++++++++--------
 3 files changed, 18 insertions(+), 8 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index b99968edd..442e79a63 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2022-01-19  Morten Welinder  <terra gnome org>
+
+       * src/mstyle.c (gnm_style_linked_sheet_changed): Add missing ref.
+       Fixes #597.
+
 2022-01-09  Morten Welinder  <terra gnome org>
 
        * src/rendered-value.c (gnm_rendered_value_new): Work around Pango
diff --git a/NEWS b/NEWS
index c3d9a9cdb..b1ec6cb07 100644
--- a/NEWS
+++ b/NEWS
@@ -14,6 +14,7 @@ Morten:
        * Fix inter-gnumeric array formula paste crash.  [#606]
        * Avoid re-querying file existance for recent files.  [Part of #602]
        * Fix rich-text rendering (based on work of Jean).  [#607]
+       * Fix crash with conditional styling.  [#597]
 
 --------------------------------------------------------------------------
 Gnumeric 1.12.50
diff --git a/src/mstyle.c b/src/mstyle.c
index c8843f848..e0205907c 100644
--- a/src/mstyle.c
+++ b/src/mstyle.c
@@ -562,21 +562,22 @@ elem_clear_contents (GnmStyle *style, GnmStyleElement elem)
        case MSTYLE_FONT_NAME:          go_string_unref (style->font_detail.name); return;
        case MSTYLE_FORMAT:             go_format_unref (style->format); return;
        case MSTYLE_VALIDATION:
-               if (style->validation)
+               if (style->validation) {
                        gnm_validation_unref (style->validation);
+                       style->validation = NULL;
+               }
                return;
        case MSTYLE_HLINK:
-               if (style->hlink)
-                       g_object_unref (style->hlink);
+               g_clear_object (&style->hlink);
                return;
        case MSTYLE_INPUT_MSG:
-               if (style->input_msg)
-                       g_object_unref (style->input_msg);
+               g_clear_object (&style->input_msg);
                return;
        case MSTYLE_CONDITIONS:
                if (style->conditions) {
                        clear_conditional_merges (style);
                        g_object_unref (style->conditions);
+                       style->conditions = NULL;
                }
                return;
        default:
@@ -998,7 +999,7 @@ gnm_style_linked_sheet_changed (GnmStyle *style)
                new_sc = sheet_conditions_share_conditions_add (new_c);
                if (new_sc) {
                        g_object_unref (new_c);
-                       new_c = new_sc;
+                       new_c = g_object_ref (new_sc);
                }
                gnm_style_set_conditions (style, new_c);
        }
@@ -1006,8 +1007,11 @@ gnm_style_linked_sheet_changed (GnmStyle *style)
 
 /**
  * gnm_style_link_sheet:
- * @style: (transfer full):
- * @sheet:
+ * @style: (transfer full): the style for which we need to set the sheet
+ * @sheet: the new sheet
+ *
+ * Returns: (transfer full): new style which may or may not be identical
+ * to the incoming.
  *
  * ABSORBS a reference to the style and sets the link count to 1.
  *