[gtk/matthiasc/for-master] Add some static assertions

[Matthias Clasen <matthiasc src gnome org>]

commit a38ba91e357ad4f4fca6b7e302672463d5dfb064
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Jan 20 22:53:25 2020 -0500

    Add some static assertions
    
    Add assertions that ensure the relationships between
    css property IDs that we rely on are preserved.

 gtk/gtkcssstaticstyle.c       | 6 ++++++
 gtk/gtkcssstylepropertyimpl.c | 3 +++
 2 files changed, 9 insertions(+)
---
diff --git a/gtk/gtkcssstaticstyle.c b/gtk/gtkcssstaticstyle.c
index 24189fcd15..0c6b8da04b 100644
--- a/gtk/gtkcssstaticstyle.c
+++ b/gtk/gtkcssstaticstyle.c
@@ -206,6 +206,12 @@ gtk_css_static_style_new_compute (GtkStyleProvider    *provider,
   return GTK_CSS_STYLE (result);
 }
 
+G_STATIC_ASSERT (GTK_CSS_PROPERTY_BORDER_TOP_STYLE == GTK_CSS_PROPERTY_BORDER_TOP_WIDTH - 1);
+G_STATIC_ASSERT (GTK_CSS_PROPERTY_BORDER_RIGHT_STYLE == GTK_CSS_PROPERTY_BORDER_RIGHT_WIDTH - 1);
+G_STATIC_ASSERT (GTK_CSS_PROPERTY_BORDER_BOTTOM_STYLE == GTK_CSS_PROPERTY_BORDER_BOTTOM_WIDTH - 1);
+G_STATIC_ASSERT (GTK_CSS_PROPERTY_BORDER_LEFT_STYLE == GTK_CSS_PROPERTY_BORDER_LEFT_WIDTH - 1);
+G_STATIC_ASSERT (GTK_CSS_PROPERTY_OUTLINE_STYLE == GTK_CSS_PROPERTY_OUTLINE_WIDTH - 1);
+
 void
 gtk_css_static_style_compute_value (GtkCssStaticStyle *style,
                                     GtkStyleProvider  *provider,
diff --git a/gtk/gtkcssstylepropertyimpl.c b/gtk/gtkcssstylepropertyimpl.c
index ba65e3cbde..e5834b1dfd 100644
--- a/gtk/gtkcssstylepropertyimpl.c
+++ b/gtk/gtkcssstylepropertyimpl.c
@@ -921,6 +921,9 @@ icon_theme_value_parse (GtkCssStyleProperty *property,
 
 /*** REGISTRATION ***/
 
+G_STATIC_ASSERT (GTK_CSS_PROPERTY_COLOR == 0);
+G_STATIC_ASSERT (GTK_CSS_PROPERTY_DPI < GTK_CSS_PROPERTY_FONT_SIZE);
+
 void
 _gtk_css_style_property_init_properties (void)
 {