From 781219dbe16fc327f5b828e1ff6fa45ec3265cba Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Tue, 2 Jul 2024 11:09:46 -0300
Subject: [PATCH] Small changes in casts from void* to functions

Macro moved to llimits.h, and casts from void* to lua_CFunction first
go through 'voidf' (a pointer to a function from void to void), a kind
of void* for functions.
---
 llimits.h | 20 ++++++++++++++++++++
 loadlib.c | 28 ++++++----------------------
 2 files changed, 26 insertions(+), 22 deletions(-)

diff --git a/llimits.h b/llimits.h
index 57e7bed7..0f3a8ecd 100644
--- a/llimits.h
+++ b/llimits.h
@@ -152,6 +152,26 @@ typedef LUAI_UACINT l_uacInt;
 #endif
 
 
+/*
+** Special type equivalent to '(void*)' for functions (to suppress some
+** warnings when converting function pointers)
+*/
+typedef void (*voidf)(void);
+
+
+/*
+** Macro to convert pointer-to-void* to pointer-to-function. This cast
+** is undefined according to ISO C, but POSIX assumes that it works.
+** (The '__extension__' in gnu compilers is only to avoid warnings.)
+*/
+#if defined(__GNUC__)
+#define cast_func(p) (__extension__ (voidf)(p))
+#else
+#define cast_func(p) ((voidf)(p))
+#endif
+
+
+
 /*
 ** non-return type
 */
diff --git a/loadlib.c b/loadlib.c
index 45db3b72..84f56ea6 100644
--- a/loadlib.c
+++ b/loadlib.c
@@ -59,11 +59,8 @@ static const char *const CLIBS = "_CLIBS";
 #define setprogdir(L)           ((void)0)
 
 
-/*
-** Special type equivalent to '(void*)' for functions in gcc
-** (to suppress warnings when converting function pointers)
-*/
-typedef void (*voidf)(void);
+/* cast void* to a Lua function */
+#define cast_Lfunc(p)	cast(lua_CFunction, cast_func(p))
 
 
 /*
@@ -96,26 +93,13 @@ static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym);
 #if defined(LUA_USE_DLOPEN)	/* { */
 /*
 ** {========================================================================
-** This is an implementation of loadlib based on the dlfcn interface.
-** The dlfcn interface is available in Linux, SunOS, Solaris, IRIX, FreeBSD,
-** NetBSD, AIX 4.2, HPUX 11, and  probably most other Unix flavors, at least
-** as an emulation layer on top of native functions.
+** This is an implementation of loadlib based on the dlfcn interface,
+** which is available in all POSIX systems.
 ** =========================================================================
 */
 
 #include <dlfcn.h>
 
-/*
-** Macro to convert pointer-to-void* to pointer-to-function. This cast
-** is undefined according to ISO C, but POSIX assumes that it works.
-** (The '__extension__' in gnu compilers is only to avoid warnings.)
-*/
-#if defined(__GNUC__)
-#define cast_func(p) (__extension__ (lua_CFunction)(p))
-#else
-#define cast_func(p) ((lua_CFunction)(p))
-#endif
-
 
 static void lsys_unloadlib (void *lib) {
   dlclose(lib);
@@ -131,7 +115,7 @@ static void *lsys_load (lua_State *L, const char *path, int seeglb) {
 
 
 static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym) {
-  lua_CFunction f = cast_func(dlsym(lib, sym));
+  lua_CFunction f = cast_Lfunc(dlsym(lib, sym));
   if (l_unlikely(f == NULL))
     lua_pushstring(L, dlerror());
   return f;
@@ -207,7 +191,7 @@ static void *lsys_load (lua_State *L, const char *path, int seeglb) {
 
 
 static lua_CFunction lsys_sym (lua_State *L, void *lib, const char *sym) {
-  lua_CFunction f = (lua_CFunction)(voidf)GetProcAddress((HMODULE)lib, sym);
+  lua_CFunction f = cast_Lfunc(GetProcAddress((HMODULE)lib, sym));
   if (f == NULL) pusherror(L);
   return f;
 }