From 405f5c54914483607194a3ba6d4e50533d92bad1 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
<31488909+miss-islington@users.noreply.github.com>
Date: Wed, 28 Jul 2021 18:02:14 -0700
Subject: [3.10] bpo-43897: Reject "_" captures and top-level MatchStar in the
AST validator (GH-27432) (GH-27435)
(cherry picked from commit 8d0647485db5af2a0f0929d6509479ca45f1281b)
Co-authored-by: Brandt Bucher <brandt@python.org>
Automerge-Triggered-By: GH:brandtbucher
---
Lib/test/test_ast.py | 6 +++++-
Python/ast.c | 48 ++++++++++++++++++++++++++++--------------------
2 files changed, 33 insertions(+), 21 deletions(-)
diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py
index ac0669a..326f3ab 100644
--- a/Lib/test/test_ast.py
+++ b/Lib/test/test_ast.py
@@ -1596,7 +1596,11 @@ class ASTValidatorTests(unittest.TestCase):
),
ast.MatchOr(
[pattern_1, pattern_x, ast.MatchSingleton('xxx')]
- )
+ ),
+ ast.MatchAs(name="_"),
+ ast.MatchStar(name="x"),
+ ast.MatchSequence([ast.MatchStar("_")]),
+ ast.MatchMapping([], [], rest="_"),
]
def test_match_validation_pattern(self):
diff --git a/Python/ast.c b/Python/ast.c
index 0a306c0..2113124 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -20,7 +20,7 @@ static int validate_patterns(struct validator *, asdl_pattern_seq *, int);
static int _validate_nonempty_seq(asdl_seq *, const char *, const char *);
static int validate_stmt(struct validator *, stmt_ty);
static int validate_expr(struct validator *, expr_ty, expr_context_ty);
-static int validate_pattern(struct validator *, pattern_ty);
+static int validate_pattern(struct validator *, pattern_ty, int);
static int
validate_name(PyObject *name)
@@ -493,7 +493,17 @@ validate_pattern_match_value(struct validator *state, expr_ty exp)
}
static int
-validate_pattern(struct validator *state, pattern_ty p)
+validate_capture(PyObject *name)
+{
+ if (_PyUnicode_EqualToASCIIString(name, "_")) {
+ PyErr_Format(PyExc_ValueError, "can't capture name '_' in patterns");
+ return 0;
+ }
+ return validate_name(name);
+}
+
+static int
+validate_pattern(struct validator *state, pattern_ty p, int star_ok)
{
int ret = -1;
if (++state->recursion_depth > state->recursion_limit) {
@@ -501,8 +511,6 @@ validate_pattern(struct validator *state, pattern_ty p)
"maximum recursion depth exceeded during compilation");
return 0;
}
- // Coming soon: https://bugs.python.org/issue43897 (thanks Batuhan)!
- // TODO: Ensure no subnodes use "_" as an ordinary identifier
switch (p->kind) {
case MatchValue_kind:
ret = validate_pattern_match_value(state, p->v.MatchValue.value);
@@ -525,7 +533,7 @@ validate_pattern(struct validator *state, pattern_ty p)
break;
}
- if (p->v.MatchMapping.rest && !validate_name(p->v.MatchMapping.rest)) {
+ if (p->v.MatchMapping.rest && !validate_capture(p->v.MatchMapping.rest)) {
ret = 0;
break;
}
@@ -575,16 +583,16 @@ validate_pattern(struct validator *state, pattern_ty p)
else {
PyErr_SetString(PyExc_ValueError,
"MatchClass cls field can only contain Name or Attribute nodes.");
- state->recursion_depth--;
- return 0;
+ ret = 0;
+ break;
}
}
for (Py_ssize_t i = 0; i < asdl_seq_LEN(p->v.MatchClass.kwd_attrs); i++) {
PyObject *identifier = asdl_seq_GET(p->v.MatchClass.kwd_attrs, i);
if (!validate_name(identifier)) {
- state->recursion_depth--;
- return 0;
+ ret = 0;
+ break;
}
}
@@ -596,10 +604,15 @@ validate_pattern(struct validator *state, pattern_ty p)
ret = validate_patterns(state, p->v.MatchClass.kwd_patterns, /*star_ok=*/0);
break;
case MatchStar_kind:
- ret = p->v.MatchStar.name == NULL || validate_name(p->v.MatchStar.name);
+ if (!star_ok) {
+ PyErr_SetString(PyExc_ValueError, "can't use MatchStar here");
+ ret = 0;
+ break;
+ }
+ ret = p->v.MatchStar.name == NULL || validate_capture(p->v.MatchStar.name);
break;
case MatchAs_kind:
- if (p->v.MatchAs.name && !validate_name(p->v.MatchAs.name)) {
+ if (p->v.MatchAs.name && !validate_capture(p->v.MatchAs.name)) {
ret = 0;
break;
}
@@ -609,10 +622,10 @@ validate_pattern(struct validator *state, pattern_ty p)
else if (p->v.MatchAs.name == NULL) {
PyErr_SetString(PyExc_ValueError,
"MatchAs must specify a target name if a pattern is given");
- return 0;
+ ret = 0;
}
else {
- ret = validate_pattern(state, p->v.MatchAs.pattern);
+ ret = validate_pattern(state, p->v.MatchAs.pattern, /*star_ok=*/0);
}
break;
case MatchOr_kind:
@@ -759,7 +772,7 @@ validate_stmt(struct validator *state, stmt_ty stmt)
}
for (i = 0; i < asdl_seq_LEN(stmt->v.Match.cases); i++) {
match_case_ty m = asdl_seq_GET(stmt->v.Match.cases, i);
- if (!validate_pattern(state, m->pattern)
+ if (!validate_pattern(state, m->pattern, /*star_ok=*/0)
|| (m->guard && !validate_expr(state, m->guard, Load))
|| !validate_body(state, m->body, "match_case")) {
return 0;
@@ -894,12 +907,7 @@ validate_patterns(struct validator *state, asdl_pattern_seq *patterns, int star_
Py_ssize_t i;
for (i = 0; i < asdl_seq_LEN(patterns); i++) {
pattern_ty pattern = asdl_seq_GET(patterns, i);
- if (pattern->kind == MatchStar_kind && !star_ok) {
- PyErr_SetString(PyExc_ValueError,
- "Can't use MatchStar within this sequence of patterns");
- return 0;
- }
- if (!validate_pattern(state, pattern)) {
+ if (!validate_pattern(state, pattern, star_ok)) {
return 0;
}
}
--
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