Convert lua_pushlstring from a macro to a function (#55)

This should avoid issues with multiple evaluations of the arguments,
which should be very rare, but could in principle happen.

2 files changed, 11 insertions, 6 deletions

diff --git a/c-api/compat-5.3.c b/c-api/compat-5.3.c
index 42b0a4b..64592d6 100644
--- a/c-api/compat-5.3.c
+++ b/c-api/compat-5.3.c
@@ -715,6 +715,14 @@ void luaL_pushresult (luaL_Buffer_53 *B) {
 #if defined( LUA_VERSION_NUM ) && LUA_VERSION_NUM <= 502
 
 
+COMPAT53_API const char *lua_pushlstring (lua_State *L, const char *s, size_t len) {
+#undef lua_pushlstring
+  lua_pushlstring(L, len > 0 ? s : "", len);
+#define lua_pushlstring COMPAT53_CONCAT(COMPAT53_PREFIX, _pushlstring_53)
+  return lua_tostring(L, -1);
+}
+
+
 COMPAT53_API int lua_geti (lua_State *L, int index, lua_Integer i) {
   index = lua_absindex(L, index);
   lua_pushinteger(L, i);
diff --git a/c-api/compat-5.3.h b/c-api/compat-5.3.h
index b730a4b..6f66dad 100644
--- a/c-api/compat-5.3.h
+++ b/c-api/compat-5.3.h
@@ -142,9 +142,6 @@ COMPAT53_API void lua_len (lua_State *L, int i);
 #define lua_pushstring(L, s) \
   (lua_pushstring((L), (s)), lua_tostring((L), -1))
 
-#define lua_pushlstring(L, s, len) \
-  ((((len) == 0) ? lua_pushlstring((L), "", 0) : lua_pushlstring((L), (s), (len))), lua_tostring((L), -1))
-
 #ifndef luaL_newlibtable
 #  define luaL_newlibtable(L, l) \
   (lua_createtable((L), 0, sizeof((l))/sizeof(*(l))-1))
@@ -290,6 +287,9 @@ typedef int (*lua_KFunction)(lua_State *L, int status, lua_KContext ctx);
 #define lua_gettable(L, i) \
   (lua_gettable((L), (i)), lua_type((L), -1))
 
+#define lua_pushlstring COMPAT53_CONCAT(COMPAT53_PREFIX, _pushlstring_53)
+COMPAT53_API const char *lua_pushlstring (lua_State *L, const char *s, size_t len);
+
 #define lua_geti COMPAT53_CONCAT(COMPAT53_PREFIX, _geti)
 COMPAT53_API int lua_geti (lua_State *L, int index, lua_Integer i);
 
@@ -352,9 +352,6 @@ COMPAT53_API void luaL_requiref (lua_State *L, const char *modname,
 #define lua_getuservalue(L, i) \
   (lua_getuservalue((L), (i)), lua_type((L), -1))
 
-#define lua_pushlstring(L, s, len) \
-  (((len) == 0) ? lua_pushlstring((L), "", 0) : lua_pushlstring((L), (s), (len)))
-
 #define lua_rawgetp(L, i, p) \
   (lua_rawgetp((L), (i), (p)), lua_type((L), -1))