[gtkmm] SpinButton: Pass signal_input double&, not double*

[Daniel Boles <dboles src gnome org>]

commit ce4066bd9cb3c1ef8276661e8fe06fa4d1f7cdf3
Author: Daniel Boles <dboles src gnome org>
Date:   Sat Jun 3 10:48:09 2017 +0100

    SpinButton: Pass signal_input double&, not double*
    
    The double* argument is to store the converted value from the text in
    the SpinButton, so there is always a target to write to. Therefore, to
    correctly use C++ style, this should use a reference and not a pointer.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=783136

 gtk/src/spinbutton.hg   |    2 +-
 tools/m4/convert_gtk.m4 |    2 ++
 2 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/gtk/src/spinbutton.hg b/gtk/src/spinbutton.hg
index 48db534..803c506 100644
--- a/gtk/src/spinbutton.hg
+++ b/gtk/src/spinbutton.hg
@@ -96,7 +96,7 @@ public:
    */
   enum { INPUT_ERROR = -1 };
 
-  _WRAP_SIGNAL(int input(double* new_value), "input")
+  _WRAP_SIGNAL(int input(double& new_value), "input")
   _WRAP_SIGNAL(bool output(), "output")
   _WRAP_SIGNAL(void wrapped(), "wrapped")
   _WRAP_SIGNAL(void value_changed(), "value_changed")
diff --git a/tools/m4/convert_gtk.m4 b/tools/m4/convert_gtk.m4
index 18dcbc0..6fc4341 100644
--- a/tools/m4/convert_gtk.m4
+++ b/tools/m4/convert_gtk.m4
@@ -20,6 +20,8 @@ include(convert_glib.m4)
 
 #
 # Basic Types
+_CONVERSION(`gdouble*',`double&',`*($3)')
+
 _CONVERSION(`time_t&',`time_t*',`&($3)')
 _CONVERSION(`time_t',`std::time_t',`$3')