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Merged
serhiy-storchaka merged 4 commits into from
Feb 16, 2019
Merged

bpo-15248: Emit a compiler warning when missed a comma before tuple or list. #11757

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8e9dc9c
bpo-15248: Emit a compiler warning when missed a comma before tuple o…
serhiy-storchaka Feb 4, 2019
8ac4d4e
Cover 1-element lists and add more tests.
serhiy-storchaka Feb 14, 2019
4803317
Update warning messages and add a What's New entry.
serhiy-storchaka Feb 15, 2019
03c75c6
Merge branch 'master' into compile-warn-perhaps-missed-comma
serhiy-storchaka Feb 15, 2019
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10 changes: 10 additions & 0 deletions Doc/whatsnew/3.8.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -115,6 +115,16 @@ Other Language Changes
a :exc:`SyntaxWarning` instead.
(Contributed by Serhiy Storchaka in :issue:`32912`.)

* The compiler now produces a :exc:`SyntaxWarning` in some cases when a comma
is missed before tuple or list. For example::

data = [
(1, 2, 3) # oops, missing comma!
(4, 5, 6)
]

(Contributed by Serhiy Storchaka in :issue:`15248`.)

* Arithmetic operations between subclasses of :class:`datetime.date` or
:class:`datetime.datetime` and :class:`datetime.timedelta` objects now return
an instance of the subclass, rather than the base class. This also affects
Expand Down
87 changes: 87 additions & 0 deletions Lib/test/test_grammar.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1263,6 +1263,93 @@ def check(test, msg='"is" with a literal'):
compile('x is True', '<testcase>', 'exec')
compile('x is ...', '<testcase>', 'exec')

def test_warn_missed_comma(self):
def check(test):
with self.assertWarnsRegex(SyntaxWarning, msg):
compile(test, '<testcase>', 'exec')
with warnings.catch_warnings():
warnings.filterwarnings('error', category=SyntaxWarning)
with self.assertRaisesRegex(SyntaxError, msg):
compile(test, '<testcase>', 'exec')

msg=r'is not callable; perhaps you missed a comma\?'
check('[(1, 2) (3, 4)]')
check('[(x, y) (3, 4)]')
check('[[1, 2] (3, 4)]')
check('[{1, 2} (3, 4)]')
check('[{1: 2} (3, 4)]')
check('[[i for i in range(5)] (3, 4)]')
check('[{i for i in range(5)} (3, 4)]')
check('[(i for i in range(5)) (3, 4)]')
check('[{i: i for i in range(5)} (3, 4)]')
check('[f"{x}" (3, 4)]')
check('[f"x={x}" (3, 4)]')
check('["abc" (3, 4)]')
check('[b"abc" (3, 4)]')
check('[123 (3, 4)]')
check('[12.3 (3, 4)]')
check('[12.3j (3, 4)]')
check('[None (3, 4)]')
check('[True (3, 4)]')
check('[... (3, 4)]')

msg=r'is not subscriptable; perhaps you missed a comma\?'
check('[{1, 2} [i, j]]')
check('[{i for i in range(5)} [i, j]]')
check('[(i for i in range(5)) [i, j]]')
check('[(lambda x, y: x) [i, j]]')
check('[123 [i, j]]')
check('[12.3 [i, j]]')
check('[12.3j [i, j]]')
check('[None [i, j]]')
check('[True [i, j]]')
check('[... [i, j]]')

msg=r'indices must be integers or slices, not tuple; perhaps you missed a comma\?'
check('[(1, 2) [i, j]]')
check('[(x, y) [i, j]]')
check('[[1, 2] [i, j]]')
check('[[i for i in range(5)] [i, j]]')
check('[f"{x}" [i, j]]')
check('[f"x={x}" [i, j]]')
check('["abc" [i, j]]')
check('[b"abc" [i, j]]')

msg=r'indices must be integers or slices, not tuple;'
check('[[1, 2] [3, 4]]')
msg=r'indices must be integers or slices, not list;'
check('[[1, 2] [[3, 4]]]')
check('[[1, 2] [[i for i in range(5)]]]')
msg=r'indices must be integers or slices, not set;'
check('[[1, 2] [{3, 4}]]')
check('[[1, 2] [{i for i in range(5)}]]')
msg=r'indices must be integers or slices, not dict;'
check('[[1, 2] [{3: 4}]]')
check('[[1, 2] [{i: i for i in range(5)}]]')
msg=r'indices must be integers or slices, not generator;'
check('[[1, 2] [(i for i in range(5))]]')
msg=r'indices must be integers or slices, not function;'
check('[[1, 2] [(lambda x, y: x)]]')
msg=r'indices must be integers or slices, not str;'
check('[[1, 2] [f"{x}"]]')
check('[[1, 2] [f"x={x}"]]')
check('[[1, 2] ["abc"]]')
msg=r'indices must be integers or slices, not'
check('[[1, 2] [b"abc"]]')
check('[[1, 2] [12.3]]')
check('[[1, 2] [12.3j]]')
check('[[1, 2] [None]]')
check('[[1, 2] [...]]')

with warnings.catch_warnings():
warnings.filterwarnings('error', category=SyntaxWarning)
compile('[(lambda x, y: x) (3, 4)]', '<testcase>', 'exec')
compile('[[1, 2] [i]]', '<testcase>', 'exec')
compile('[[1, 2] [0]]', '<testcase>', 'exec')
compile('[[1, 2] [True]]', '<testcase>', 'exec')
compile('[[1, 2] [1:2]]', '<testcase>', 'exec')
compile('[{(1, 2): 3} [i, j]]', '<testcase>', 'exec')

def test_binary_mask_ops(self):
x = 1 & 1
x = 1 ^ 1
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2019-02-04-21-10-17.bpo-15248.2sXSZZ.rst
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@@ -0,0 +1,2 @@
The compiler emits now syntax warnings in the case when a comma is likely
missed before tuple or list.
146 changes: 140 additions & 6 deletions Python/compile.c
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Original file line number Diff line number Diff line change
Expand Up @@ -175,7 +175,7 @@ static int compiler_addop(struct compiler *, int);
static int compiler_addop_i(struct compiler *, int, Py_ssize_t);
static int compiler_addop_j(struct compiler *, int, basicblock *, int);
static int compiler_error(struct compiler *, const char *);
static int compiler_warn(struct compiler *, const char *);
static int compiler_warn(struct compiler *, const char *, ...);
static int compiler_nameop(struct compiler *, identifier, expr_context_ty);

static PyCodeObject *compiler_mod(struct compiler *, mod_ty);
Expand Down Expand Up @@ -3766,6 +3766,122 @@ compiler_compare(struct compiler *c, expr_ty e)
return 1;
}

static PyTypeObject *
infer_type(expr_ty e)
{
switch (e->kind) {
case Tuple_kind:
return &PyTuple_Type;
case List_kind:
case ListComp_kind:
return &PyList_Type;
case Dict_kind:
case DictComp_kind:
return &PyDict_Type;
case Set_kind:
case SetComp_kind:
return &PySet_Type;
case GeneratorExp_kind:
return &PyGen_Type;
case Lambda_kind:
return &PyFunction_Type;
case JoinedStr_kind:
case FormattedValue_kind:
return &PyUnicode_Type;
case Constant_kind:
return e->v.Constant.value->ob_type;
default:
return NULL;
}
}

static int
check_caller(struct compiler *c, expr_ty e)
{
switch (e->kind) {
case Constant_kind:
case Tuple_kind:
case List_kind:
case ListComp_kind:
case Dict_kind:
case DictComp_kind:
case Set_kind:
case SetComp_kind:
case GeneratorExp_kind:
case JoinedStr_kind:
case FormattedValue_kind:
return compiler_warn(c, "'%.200s' object is not callable; "
"perhaps you missed a comma?",
infer_type(e)->tp_name);
default:
return 1;
}
}

static int
check_subscripter(struct compiler *c, expr_ty e)
{
PyObject *v;

switch (e->kind) {
case Constant_kind:
v = e->v.Constant.value;
if (!(v == Py_None || v == Py_Ellipsis ||
PyLong_Check(v) || PyFloat_Check(v) || PyComplex_Check(v) ||
PyAnySet_Check(v)))
{
return 1;
}
/* fall through */
case Set_kind:
case SetComp_kind:
case GeneratorExp_kind:
case Lambda_kind:
return compiler_warn(c, "'%.200s' object is not subscriptable; "
"perhaps you missed a comma?",
infer_type(e)->tp_name);
default:
return 1;
}
}

static int
check_index(struct compiler *c, expr_ty e, slice_ty s)
{
PyObject *v;

if (s->kind != Index_kind) {
return 1;
}
PyTypeObject *index_type = infer_type(s->v.Index.value);
if (index_type == NULL
|| PyType_FastSubclass(index_type, Py_TPFLAGS_LONG_SUBCLASS)
|| index_type == &PySlice_Type) {
return 1;
}

switch (e->kind) {
case Constant_kind:
v = e->v.Constant.value;
if (!(PyUnicode_Check(v) || PyBytes_Check(v) || PyTuple_Check(v))) {
return 1;
}
/* fall through */
case Tuple_kind:
case List_kind:
case ListComp_kind:
case JoinedStr_kind:
case FormattedValue_kind:
return compiler_warn(c, "%.200s indices must be integers or slices, "
"not %.200s; "
"perhaps you missed a comma?",
infer_type(e)->tp_name,
index_type->tp_name);
default:
return 1;
}
}

static int
maybe_optimize_method_call(struct compiler *c, expr_ty e)
{
Expand Down Expand Up @@ -3801,7 +3917,9 @@ compiler_call(struct compiler *c, expr_ty e)
{
if (maybe_optimize_method_call(c, e) > 0)
return 1;

if (!check_caller(c, e->v.Call.func)) {
return 0;
}
VISIT(c, expr, e->v.Call.func);
return compiler_call_helper(c, 0,
e->v.Call.args,
Expand Down Expand Up @@ -4694,6 +4812,12 @@ compiler_visit_expr1(struct compiler *c, expr_ty e)
VISIT_SLICE(c, e->v.Subscript.slice, AugLoad);
break;
case Load:
if (!check_subscripter(c, e->v.Subscript.value)) {
return 0;
}
if (!check_index(c, e->v.Subscript.value, e->v.Subscript.slice)) {
return 0;
}
VISIT(c, expr, e->v.Subscript.value);
VISIT_SLICE(c, e->v.Subscript.slice, Load);
break;
Expand Down Expand Up @@ -4987,20 +5111,30 @@ compiler_error(struct compiler *c, const char *errstr)
and returns 0.
*/
static int
compiler_warn(struct compiler *c, const char *errstr)
compiler_warn(struct compiler *c, const char *format, ...)
{
PyObject *msg = PyUnicode_FromString(errstr);
va_list vargs;
#ifdef HAVE_STDARG_PROTOTYPES
va_start(vargs, format);
#else
va_start(vargs);
#endif
PyObject *msg = PyUnicode_FromFormatV(format, vargs);
va_end(vargs);
if (msg == NULL) {
return 0;
}
if (PyErr_WarnExplicitObject(PyExc_SyntaxWarning, msg, c->c_filename,
c->u->u_lineno, NULL, NULL) < 0)
{
Py_DECREF(msg);
if (PyErr_ExceptionMatches(PyExc_SyntaxWarning)) {
/* Replace the SyntaxWarning exception with a SyntaxError
to get a more accurate error report */
PyErr_Clear();
return compiler_error(c, errstr);
assert(PyUnicode_AsUTF8(msg) != NULL);
compiler_error(c, PyUnicode_AsUTF8(msg));
}
Py_DECREF(msg);
return 0;
}
Py_DECREF(msg);
Expand Down