Re: Bug in storing -0 constant
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- Subject: Re: Bug in storing -0 constant
- From: Roberto Ierusalimschy <roberto@...>
- Date: Sun, 6 Apr 2008 10:40:35 -0300
> I've found a small bug in Lua 5.1.3 (and probably older versions as
> well). The numbers 0 and -0 are treated as identical when used as table
> keys. That's OK, but it leads to a problem when both numbers appear as
> constants in the same function, because the compiler only puts the first
> one into the constant table in the bytecode.
This is a known issue:
http://lua-users.org/lists/lua-l/2005-01/msg00114.html
Many thanks anyway.
Update: it is not hard to fix this behavior:
--- lcode.c 2008年04月02日 16:16:06 2.35
+++ lcode.c 2008年04月06日 13:31:38
@@ -696,7 +696,7 @@
e2.t = e2.f = NO_JUMP; e2.k = VKNUM; e2.u.nval = 0;
switch (op) {
case OPR_MINUS: {
- if (isnumeral(e)) /* -constant? */
+ if (isnumeral(e) && e->u.nval != 0) /* minus non-zero constant? */
e->u.nval = luai_numunm(NULL, e->u.nval);
else {
luaK_exp2anyreg(fs, e);
-- Roberto