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silly bug in 5.2 beta: assignment conflict code did not test to check 

whether variable was a table element
This commit is contained in:
Roberto Ierusalimschy 2011-10-24 12:51:44 -02:00
parent 1dd8af67b6
commit 6819c2a98a
1 changed files with 20 additions and 17 deletions
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37
lparser.c
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@ -1,5 +1,5 @@
/*
** $Id: lparser.c,v 2.119 2011/09/14 17:40:26 roberto Exp roberto $
** $Id: lparser.c,v 2.120 2011/09/30 12:44:45 roberto Exp roberto $
** Lua Parser
** See Copyright Notice in lua.h
*/
@ -1106,31 +1106,34 @@ struct LHS_assign {
/*
** check whether, in an assignment to a local variable, the local variable
** is needed in a previous assignment (to a table). If so, save original
** local value in a safe place and use this safe copy in the previous
** assignment.
** check whether, in an assignment to an upvalue/local variable, the
** upvalue/local variable is begin used in a previous assignment to a
** table. If so, save original upvalue/local value in a safe place and
** use this safe copy in the previous assignment.
*/
static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
FuncState *fs = ls->fs;
int extra = fs->freereg; /* eventual position to save local variable */
int conflict = 0;
for (; lh; lh = lh->prev) {
/* conflict in table 't'? */
if (lh->v.u.ind.vt == v->k && lh->v.u.ind.t == v->u.info) {
conflict = 1;
lh->v.u.ind.vt = VLOCAL;
lh->v.u.ind.t = extra; /* previous assignment will use safe copy */
}
/* conflict in index 'idx'? */
if (v->k == VLOCAL && lh->v.u.ind.idx == v->u.info) {
conflict = 1;
lh->v.u.ind.idx = extra; /* previous assignment will use safe copy */
for (; lh; lh = lh->prev) { /* check all previous assignments */
if (lh->v.k == VINDEXED) { /* assigning to a table? */
/* table is the upvalue/local being assigned now? */
if (lh->v.u.ind.vt == v->k && lh->v.u.ind.t == v->u.info) {
conflict = 1;
lh->v.u.ind.vt = VLOCAL;
lh->v.u.ind.t = extra; /* previous assignment will use safe copy */
}
/* index is the local being assigned? (index cannot be upvalue) */
if (v->k == VLOCAL && lh->v.u.ind.idx == v->u.info) {
conflict = 1;
lh->v.u.ind.idx = extra; /* previous assignment will use safe copy */
}
}
}
if (conflict) {
/* copy upvalue/local value to a temporary (in position 'extra') */
OpCode op = (v->k == VLOCAL) ? OP_MOVE : OP_GETUPVAL;
luaK_codeABC(fs, op, fs->freereg, v->u.info, 0); /* make copy */
luaK_codeABC(fs, op, extra, v->u.info, 0);
luaK_reserveregs(fs, 1);
}
}