Add warning for assignment to None, True and False. This is patch

549213 by Jeremy (checking in for him since he's away and busy).
This commit is contained in:
Guido van Rossum 2002-12-23 16:35:23 +00:00
parent a4deda0d11
commit 9c8a0866c9
2 changed files with 100 additions and 30 deletions

View File

@ -84,6 +84,10 @@ Type/class unification and new-style classes
Core and builtins
-----------------
- Assignment to None has long been frowned upon. Now there's a
warning message when you do this. It also warns against assignment
to True or False.
- A frame object's f_lineno attribute can now be written to from a
trace function to change which line will execute next. A command to
exploit this from pdb has been added. [SF patch #643835]

View File

@ -575,6 +575,7 @@ block_pop(struct compiling *c, int type)
/* Prototype forward declarations */
static int issue_warning(const char *, const char *, int);
static int symtable_warn(struct symtable *, char *);
static int com_init(struct compiling *, const char *);
static void com_free(struct compiling *);
static void com_push(struct compiling *, int);
@ -1006,6 +1007,64 @@ none_assignment_check(struct compiling *c, char *name, int assigning)
return 0;
}
static int num_literals = 3;
static char *literal_names[] = {"None", "True", "False"};
static PyObject *literals;
static int
init_literals(void)
{
int i;
literals = PyDict_New();
if (literals == NULL)
return -1;
for (i = 0; i < num_literals; i++)
if (PyDict_SetItemString(literals, literal_names[i],
Py_None) < 0)
return -1;
return 0;
}
static int
check_literal(PyObject *name, struct compiling *c, struct symtable *st)
{
/* check for literal names that will become keywords in the future */
if (literals == NULL && init_literals() < 0)
return -1;
if (!PyString_Check(name))
return -1;
if (PyDict_GetItem(literals, name)) {
char buf[1024];
PyOS_snprintf(buf, sizeof(buf), "'%s' may become a keyword",
PyString_AS_STRING(name));
if (c && (issue_warning(buf, c->c_filename, c->c_lineno) < 0))
return -1;
if (st && (symtable_warn(st, buf) < 0))
return -1;
}
return 0;
}
static int
check_literal_str(const char *name, struct compiling *c, struct symtable *st)
{
int i;
for (i = 0; i < num_literals; i++)
if (strcmp(literal_names[i], name) == 0) {
char buf[1024];
PyOS_snprintf(buf, sizeof(buf),
"'%s' may become a keyword", name);
if (c &&
issue_warning(buf, c->c_filename, c->c_lineno) < 0)
return -1;
if (st && symtable_warn(st, buf) < 0)
return -1;
}
return 0;
}
static void
com_addop_varname(struct compiling *c, int kind, char *name)
{
@ -1063,6 +1122,14 @@ com_addop_varname(struct compiling *c, int kind, char *name)
}
Py_DECREF(v);
if (kind == VAR_STORE || kind == VAR_DELETE) {
if (check_literal(v, c, NULL) < 0) {
c->c_errors++;
i = 255;
goto done;
}
}
switch (kind) {
case VAR_LOAD:
switch (scope) {
@ -1130,6 +1197,7 @@ com_addopname(struct compiling *c, int op, node *n)
/* XXX it is possible to write this code without the 1000
chars on the total length of dotted names, I just can't be
bothered right now */
if (TYPE(n) == STAR)
name = "*";
else if (TYPE(n) == dotted_name) {
@ -1138,6 +1206,10 @@ com_addopname(struct compiling *c, int op, node *n)
name = buffer;
for (i = 0; i < NCH(n); i += 2) {
char *s = STR(CHILD(n, i));
if (check_literal_str(s, c, NULL) < 0) {
name = NULL;
break;
}
if (p + strlen(s) > buffer + (sizeof buffer) - 2) {
com_error(c, PyExc_MemoryError,
"dotted_name too long");
@ -1153,6 +1225,8 @@ com_addopname(struct compiling *c, int op, node *n)
else {
REQ(n, NAME);
name = STR(n);
if (check_literal_str(name, c, NULL) < 0)
name = NULL;
}
com_addop_name(c, op, name);
}
@ -2972,9 +3046,13 @@ com_import_stmt(struct compiling *c, node *n)
} else {
tup = PyTuple_New((NCH(n) - 2)/2);
for (i = 3; i < NCH(n); i += 2) {
char *s = STR(CHILD(CHILD(n, i), 0));
if (check_literal_str(s, c, NULL) < 0) {
c->c_errors++;
return;
}
PyTuple_SET_ITEM(tup, (i-3)/2,
PyString_FromString(STR(
CHILD(CHILD(n, i), 0))));
PyString_FromString(s));
}
}
com_addoparg(c, LOAD_CONST, com_addconst(c, tup));
@ -3914,40 +3992,23 @@ com_fplist(struct compiling *c, node *n)
static void
com_arglist(struct compiling *c, node *n)
{
int nch, i, narg;
int i;
int complex = 0;
char nbuf[30];
REQ(n, varargslist);
/* varargslist:
(fpdef ['=' test] ',')* (fpdef ['=' test] | '*' .....) */
nch = NCH(n);
/* Enter all arguments in table of locals */
for (i = 0, narg = 0; i < nch; i++) {
node *ch = CHILD(n, i);
node *fp;
if (TYPE(ch) == STAR || TYPE(ch) == DOUBLESTAR)
break;
REQ(ch, fpdef); /* fpdef: NAME | '(' fplist ')' */
fp = CHILD(ch, 0);
if (TYPE(fp) != NAME) {
PyOS_snprintf(nbuf, sizeof(nbuf), ".%d", i);
/* Check if the argument list includes nested tuples */
for (i = 0; i < NCH(n); i++)
if (TYPE(CHILD(n, i)) == LPAR) {
complex = 1;
}
narg++;
/* all name updates handled by symtable */
if (++i >= nch)
break;
ch = CHILD(n, i);
if (TYPE(ch) == EQUAL)
i += 2;
else
REQ(ch, COMMA);
}
}
/* If it does, generate code to unpack them. */
if (complex) {
/* Generate code for complex arguments only after
having counted the simple arguments */
int ilocal = 0;
for (i = 0; i < nch; i++) {
for (i = 0; i < NCH(n); i++) {
node *ch = CHILD(n, i);
node *fp;
if (TYPE(ch) == STAR || TYPE(ch) == DOUBLESTAR)
@ -3960,7 +4021,7 @@ com_arglist(struct compiling *c, node *n)
com_fpdef(c, ch);
}
ilocal++;
if (++i >= nch)
if (++i >= NCH(n))
break;
ch = CHILD(n, i);
if (TYPE(ch) == EQUAL)
@ -5359,7 +5420,7 @@ static void
symtable_params(struct symtable *st, node *n)
{
int i, complex = -1, ext = 0;
node *c = NULL;
node *c = NULL, *ch = NULL;
if (TYPE(n) == parameters) {
n = CHILD(n, 1);
@ -5376,9 +5437,14 @@ symtable_params(struct symtable *st, node *n)
if (TYPE(c) == test) {
continue;
}
if (TYPE(CHILD(c, 0)) == NAME)
ch = CHILD(c, 0);
if (TYPE(ch) == NAME) {
if (check_literal_str(STR(ch), NULL, st) < 0) {
st->st_errors++;
return;
}
symtable_add_def(st, STR(CHILD(c, 0)), DEF_PARAM);
else {
} else {
char nbuf[30];
PyOS_snprintf(nbuf, sizeof(nbuf), ".%d", i);
symtable_add_def(st, nbuf, DEF_PARAM);