d/patches: add patch to remove pre-ANSI function declarations

Pre-ANSI function declarators which do not declare their parameters have been
removed in C23 and the syntax reused for declaring functions with no parameters
(like C++).  GCC 15 defaults to C23, so these declarators will cause an FTBFS.

Update the function definitions to have ANSI prototypes where these are
missing, make them static and replace the obsolete declarations with modern
equivalents.

Closes: #1098100

Signed-off-by: Jeremy Sowden <azazel@debian.org>

debian/patches/01-fix-pre-ansi-function-declarations.patch

@@ -0,0 +1,55 @@
+Author: Jeremy Sowden <jeremy@azazel.net>
+Last-Update: 2025-02-27
+Bug-Debian: https://bugs.debian.org/1098100
+Forwarded: yes
+Applied-Upstream: commit:97d7faf9150414ddfc3a53cd9905e628dd60685f
+Description: remove pre-ANSI function declarations
+ Pre-ANSI function declarators which do not declare their parameters have been
+ removed in C23 and the syntax reused for declaring functions with no parameters
+ (like C++).  GCC 15 defaults to C23, so these declarators will cause an FTBFS.
+ .
+ Update the function definitions to have ANSI prototypes where these are
+ missing, make them static and replace the obsolete declarations with modern
+ equivalents.
+
+--- a/Src/wmCalClock.c
++++ b/Src/wmCalClock.c
+@@ -119,6 +119,8 @@
+ 
+ 
+ 
++static double jd(int ny, int nm, int nd, double UT);
++static double hour24(double hour);
+ 
+ void ParseCMDLine(int argc, char *argv[]);
+ void ButtonPressEvent(XButtonEvent *);
+@@ -310,7 +312,7 @@
+     int 		Year, Month, DayOfWeek, DayOfMonth, OldDayOfMonth;
+     int			Hours, Mins, Secs, OldSecs, digit, xoff, D[10], xsize;
+     time_t		CurrentLocalTime;
+-    double		UT, TU, TU2, TU3, T0, gmst, jd(), hour24();
++    double		UT, TU, TU2, TU3, T0, gmst;
+ 
+ 
+     /*
+@@ -939,9 +941,7 @@
+  *  Compute the Julian Day number for the given date.
+  *  Julian Date is the number of days since noon of Jan 1 4713 B.C.
+  */
+-double jd(ny, nm, nd, UT)
+-int ny, nm, nd;
+-double UT;
++static double jd(int ny, int nm, int nd, double UT)
+ {
+         double A, B, C, D, JD, day;
+ 
+@@ -976,8 +976,7 @@
+ 
+ }
+ 
+-double hour24(hour)
+-double hour;
++static double hour24(double hour)
+ {
+         int n;
+ 

debian/patches/series

@@ -0,0 +1 @@
+01-fix-pre-ansi-function-declarations.patch