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Calls cannot be tail in the scope of a to-be-closed variable

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A to-be-closed variable must be closed when a block ends, so even
a 'return foo()' cannot directly returns the results of 'foo'; the
function must close the scope before returning.
This commit is contained in:
Roberto Ierusalimschy
2018-12-04 15:01:42 -02:00
parent 6d04537ea6
commit 28d829c867
4 changed files with 21 additions and 16 deletions
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5
lparser.c
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@@ -53,6 +53,7 @@ typedef struct BlockCnt {
lu_byte nactvar; /* # active locals outside the block */
lu_byte upval; /* true if some variable in the block is an upvalue */
lu_byte isloop; /* true if 'block' is a loop */
lu_byte insidetbc; /* true if inside the scope of a to-be-closed var. */
} BlockCnt;
@@ -510,6 +511,7 @@ static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
bl->firstlabel = fs->ls->dyd->label.n;
bl->firstgoto = fs->ls->dyd->gt.n;
bl->upval = 0;
bl->insidetbc = (fs->bl != NULL && fs->bl->insidetbc);
bl->previous = fs->bl;
fs->bl = bl;
lua_assert(fs->freereg == fs->nactvar);
@@ -1631,6 +1633,7 @@ static void tocloselocalstat (LexState *ls) {
checknext(ls, '=');
exp1(ls, 0);
markupval(fs, fs->nactvar);
fs->bl->insidetbc = 1; /* in the scope of a to-be-closed variable */
adjustlocalvars(ls, 1);
luaK_codeABC(fs, OP_TBC, fs->nactvar - 1, 0, 0);
}
@@ -1701,7 +1704,7 @@ static void retstat (LexState *ls) {
nret = explist(ls, &e); /* optional return values */
if (hasmultret(e.k)) {
luaK_setmultret(fs, &e);
if (e.k == VCALL && nret == 1) { /* tail call? */
if (e.k == VCALL && nret == 1 && !fs->bl->insidetbc) { /* tail call? */
SET_OPCODE(getinstruction(fs,&e), OP_TAILCALL);
lua_assert(GETARG_A(getinstruction(fs,&e)) == fs->nactvar);
}