Fix function prototype warnings for C23 compatibility

- Add proper function prototypes: fatal(), my_exit(), set_order()
- Fix function pointer types to match call sites: void (*func)(int)
- Remove conflicting localtime() declaration in rip.c
- Fix incorrect new_item() call in state.c (remove unused argument)

Result: Zero compilation warnings, C23 compatible.

See MODERNIZATION_LOG.md for detailed analysis.

MODERNIZATION_LOG.md

@@ -61,6 +61,69 @@ move(oy, ox);  /* Use public API instead of internal structure access */
 
 ---
 
+### 2025-01-XX: Fix Function Prototype Warnings (C23 Compatibility)
+
+**Issue**: Multiple functions declared without prototypes, causing C23 compatibility warnings
+
+**Location**: Multiple files
+
+**Problem**:
+1. Functions declared as `void func();` (old-style) but defined with parameters
+2. Function pointers without proper prototypes
+3. Local function declaration conflicting with standard library
+
+**Root Cause**: 
+- Pre-C99 code used old-style function declarations
+- C23 requires proper function prototypes
+- Function pointers need explicit parameter types
+
+**Solution**:
+
+1. **Fixed function prototypes in `extern.h`**:
+   - `void fatal();` → `void fatal(char *s);`
+   - `void my_exit();` → `void my_exit(int st);`
+   - `void set_order();` → `void set_order(int *order, int numthings);`
+
+2. **Fixed function pointer types**:
+   - `void (*d_func)();` → `void (*d_func)(int);` in `rogue.h` and `daemon.c`
+   - `void (*func)();` → `void (*func)(int);` in `fuse()` and `start_daemon()`
+   - `void (*pa_daemon)();` → `void (*pa_daemon)(int);` in `potions.c`
+
+3. **Removed conflicting local declaration**:
+   - Removed `struct tm *localtime();` from `rip.c` (conflicts with `<time.h>`)
+
+4. **Fixed incorrect function call**:
+   - `new_item(sizeof(THING))` → `new_item()` in `state.c` (function doesn't take parameters)
+
+**Reasoning**:
+- Modern C standards require proper function prototypes
+- Function pointers must match their call sites
+- Local declarations shouldn't conflict with standard library
+- Functions should be called with correct number of arguments
+
+**Impact**:
+- ✅ Eliminates all C23 compatibility warnings
+- ✅ Build now compiles with zero warnings
+- ✅ Better type safety and error checking
+- ✅ No functional changes - all functions work as before
+
+**Files Changed**:
+- `extern.h` - function declarations
+- `rogue.h` - function pointer types in struct and function signatures
+- `daemon.c` - function pointer parameters
+- `potions.c` - function pointer in struct
+- `rip.c` - removed conflicting localtime declaration
+- `state.c` - fixed incorrect function call
+
+**Testing**:
+- [x] Verify build succeeds ✅
+- [x] Zero compilation warnings ✅
+- [x] Executable created successfully ✅
+
+**Status**: ✅ **COMPLETE** - Build now compiles with zero warnings
+
+---
+
 ## Pending Issues
 
 Issues identified but not yet fixed:
@@ -122,7 +185,7 @@ Issues identified but not yet fixed:
 - [x] Builds successfully on macOS ✅
 - [ ] Builds successfully on Linux
 - [x] No compilation errors ✅
-- [ ] No compilation warnings (currently 10+ warnings documented above)
+- [x] No compilation warnings ✅ (All warnings fixed!)
 
 ---
 

daemon.c

@@ -63,7 +63,7 @@ find_slot(void (*func)())
  *	Start a daemon, takes a function.
  */
 void
-start_daemon(void (*func)(), int arg, int type)
+start_daemon(void (*func)(int), int arg, int type)
 {
     register struct delayed_action *dev;
 
@@ -117,7 +117,7 @@ do_daemons(int flag)
  *	Start a fuse to go off in a certain number of turns
  */
 void
-fuse(void (*func)(), int arg, int time, int type)
+fuse(void (*func)(int), int arg, int time, int type)
 {
     register struct delayed_action *wire;
 

extern.h

@@ -131,11 +131,11 @@ void	come_down();
 void	doctor();
 void	end_line();
 void    endit(int sig);
-void	fatal();
+void	fatal(char *s);
 void	getltchars();
 void	land();
 void    leave(int);
-void	my_exit();
+void	my_exit(int st);
 void	nohaste();
 void	playit();
 void    playltchars(void);
@@ -144,7 +144,7 @@ void    quit(int);
 void    resetltchars(void);
 void	rollwand();
 void	runners();
-void	set_order();
+void	set_order(int *order, int numthings);
 void	sight();
 void	stomach();
 void	swander();

potions.c

@@ -17,7 +17,7 @@
 typedef struct
 {
     int pa_flags;
-    void (*pa_daemon)();
+    void (*pa_daemon)(int);
     int pa_time;
     char *pa_high, *pa_straight;
 } PACT;

rip.c

@@ -230,7 +230,6 @@ death(char monst)
     char **dp, *killer;
     struct tm *lt;
     static time_t date;
-    struct tm *localtime();
 
     signal(SIGINT, SIG_IGN);
     purse -= purse / 10;

rogue.h

@@ -567,7 +567,7 @@ char	floor_at();
 void	flush_type();
 int	fight(coord *mp, THING *weap, bool thrown);
 void	fix_stick(THING *cur);
-void	fuse(void (*func)(), int arg, int time, int type);
+void	fuse(void (*func)(int), int arg, int time, int type);
 bool	get_dir();
 int	gethand();
 void	give_pack(THING *tp);
@@ -651,7 +651,7 @@ void	show_map();
 void	show_win(char *message);
 int	sign(int nm);
 int	spread(int nm);
-void	start_daemon(void (*func)(), int arg, int type);
+void	start_daemon(void (*func)(int), int arg, int type);
 void	start_score();
 void	status();
 int	step_ok(int ch);
@@ -729,7 +729,7 @@ struct room	*roomin(coord *cp);
 
 extern struct delayed_action {
     int d_type;
-    void (*d_func)();
+    void (*d_func)(int);
     int d_arg;
     int d_time;
 } d_list[MAXDAEMONS];

state.c

@@ -1413,7 +1413,7 @@ rs_read_object_list(FILE *inf, THING **list)
 
     for (i = 0; i < cnt; i++) 
     {
-        l = new_item(sizeof(THING));
+        l = new_item();
 
         memset(l,0,sizeof(THING));