contrib/lua: update to 5.4.2

Merge commit '0ea45b9cd43ce1247eb3eee9bfd5cee3d19068e7' into main

1 files changed, 25 insertions, 2 deletions

diff --git a/contrib/lua/src/lapi.h b/contrib/lua/src/lapi.h
index 8e16ad53d999..41216b270902 100644
--- a/contrib/lua/src/lapi.h
+++ b/contrib/lua/src/lapi.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lapi.h,v 2.9.1.1 2017/04/19 17:20:42 roberto Exp $
+** $Id: lapi.h $
 ** Auxiliary functions from Lua API
 ** See Copyright Notice in lua.h
 */
@@ -11,14 +11,37 @@
 #include "llimits.h"
 #include "lstate.h"
 
+
+/* Increments 'L->top', checking for stack overflows */
 #define api_incr_top(L)   {L->top++; api_check(L, L->top <= L->ci->top, \
 				"stack overflow");}
 
+
+/*
+** If a call returns too many multiple returns, the callee may not have
+** stack space to accommodate all results. In this case, this macro
+** increases its stack space ('L->ci->top').
+*/
 #define adjustresults(L,nres) \
-    { if ((nres) == LUA_MULTRET && L->ci->top < L->top) L->ci->top = L->top; }
+    { if ((nres) <= LUA_MULTRET && L->ci->top < L->top) L->ci->top = L->top; }
+
 
+/* Ensure the stack has at least 'n' elements */
 #define api_checknelems(L,n)	api_check(L, (n) < (L->top - L->ci->func), \
 				  "not enough elements in the stack")
 
 
+/*
+** To reduce the overhead of returning from C functions, the presence of
+** to-be-closed variables in these functions is coded in the CallInfo's
+** field 'nresults', in a way that functions with no to-be-closed variables
+** with zero, one, or "all" wanted results have no overhead. Functions
+** with other number of wanted results, as well as functions with
+** variables to be closed, have an extra check.
+*/
+
+#define hastocloseCfunc(n)	((n) < LUA_MULTRET)
+
+#define codeNresults(n)		(-(n) - 3)
+
 #endif