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bpo-40334: Produce better error messages on invalid targets (GH-20106)

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The following error messages get produced:
- `cannot delete ...` for invalid `del` targets
- `... is an illegal 'for' target` for invalid targets in for
  statements
- `... is an illegal 'with' target` for invalid targets in
  with statements

Additionally, a few `cut`s were added in various places before the
invocation of the `invalid_*` rule, in order to speed things
up.

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
This commit is contained in:
Lysandros Nikolaou 2020-06-19 02:10:43 +03:00 • committed by GitHub
parent d906f0ec1a
commit 01ece63d42
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GPG key ID: 4AEE18F83AFDEB23
6 changed files with 2651 additions and 2256 deletions
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28
Parser/pegen.c
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@ -380,7 +380,6 @@ _PyPegen_raise_error(Parser *p, PyObject *errtype, const char *errmsg, ...)
return NULL;
}
void *
_PyPegen_raise_error_known_location(Parser *p, PyObject *errtype,
Py_ssize_t lineno, Py_ssize_t col_offset,
@ -2086,7 +2085,7 @@ _PyPegen_make_module(Parser *p, asdl_seq *a) {
// Error reporting helpers
expr_ty
_PyPegen_get_invalid_target(expr_ty e)
_PyPegen_get_invalid_target(expr_ty e, TARGETS_TYPE targets_type)
{
if (e == NULL) {
return NULL;
@ -2096,7 +2095,7 @@ _PyPegen_get_invalid_target(expr_ty e)
Py_ssize_t len = asdl_seq_LEN(CONTAINER->v.TYPE.elts);\
for (Py_ssize_t i = 0; i < len; i++) {\
expr_ty other = asdl_seq_GET(CONTAINER->v.TYPE.elts, i);\
expr_ty child = _PyPegen_get_invalid_target(other);\
expr_ty child = _PyPegen_get_invalid_target(other, targets_type);\
if (child != NULL) {\
return child;\
}\
@ -2110,16 +2109,29 @@ _PyPegen_get_invalid_target(expr_ty e)
// we don't need to visit it recursively.
switch (e->kind) {
case List_kind: {
case List_kind:
VISIT_CONTAINER(e, List);
return NULL;
}
case Tuple_kind: {
case Tuple_kind:
VISIT_CONTAINER(e, Tuple);
return NULL;
}
case Starred_kind:
return _PyPegen_get_invalid_target(e->v.Starred.value);
if (targets_type == DEL_TARGETS) {
return e;
}
return _PyPegen_get_invalid_target(e->v.Starred.value, targets_type);
case Compare_kind:
// This is needed, because the `a in b` in `for a in b` gets parsed
// as a comparison, and so we need to search the left side of the comparison
// for invalid targets.
if (targets_type == FOR_TARGETS) {
cmpop_ty cmpop = (cmpop_ty) asdl_seq_GET(e->v.Compare.ops, 0);
if (cmpop == In) {
return _PyPegen_get_invalid_target(e->v.Compare.left, targets_type);
}
return NULL;
}
return e;
case Name_kind:
case Subscript_kind:
case Attribute_kind: