Re: Question about luaM_reallocv in lmem.h

[Mike Pall <mikelu-0503@...>]

Hi,

Bogdan Marinescu wrote:
>     While trying to port lua to an embedded 16-bit platform, the
> compiler warns me that the comparison in luaM_reallocv is always true:

The same occurs on 64 bit platforms. I've already reported this to
Roberto for Lua 5.1-work4.

Below is a patch to silence the compiler (and to optimize the conditional
away when it's not needed).

Bye,
     Mike

--- lua-5.1-work5/src/lmem.h	2004-12-01 16:46:18.000000000 +0100
+++ lua-5.1-work5-lmemfix/src/lmem.h	2005-03-06 22:57:13.019119208 +0100
@@ -21,7 +21,8 @@
 void *luaM_toobig (lua_State *L);
 
 #define luaM_reallocv(L,b,on,n,e) \
-  ((cast(unsigned int, (n)+1) <= MAX_SIZET/(e)) ?  /* +1 to avoid warnings */ \
+  (((sizeof(unsigned int) < sizeof(size_t) ? 0 : cast(unsigned int, (n)+1)) \
+    <= MAX_SIZET/(e)) ?  /* to avoid warnings */ \
     luaM_realloc_(L, (b), (on)*(e), (n)*(e)) : \
     luaM_toobig(L))