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bpo-44589: raise a SyntaxError when mapping patterns have duplicate literal keys (GH-27131)

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Jack DeVries 2021-07-14 20:38:42 -04:00 • committed by GitHub
parent 3b8075f907
commit 2693132292
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4 changed files with 82 additions and 19 deletions
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45
Python/compile.c
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@ -6176,20 +6176,53 @@ compiler_pattern_mapping(struct compiler *c, pattern_ty p, pattern_context *pc)
}
// Collect all of the keys into a tuple for MATCH_KEYS and
// COPY_DICT_WITHOUT_KEYS. They can either be dotted names or literals:
// Maintaining a set of Constant_kind kind keys allows us to raise a
// SyntaxError in the case of duplicates.
PyObject *seen = PySet_New(NULL);
if (seen == NULL) {
return 0;
}
// NOTE: goto error on failure in the loop below to avoid leaking `seen`
for (Py_ssize_t i = 0; i < size; i++) {
expr_ty key = asdl_seq_GET(keys, i);
if (key == NULL) {
const char *e = "can't use NULL keys in MatchMapping "
"(set 'rest' parameter instead)";
SET_LOC(c, ((pattern_ty) asdl_seq_GET(patterns, i)));
return compiler_error(c, e);
compiler_error(c, e);
goto error;
}
if (!MATCH_VALUE_EXPR(key)) {
if (key->kind == Constant_kind) {
int in_seen = PySet_Contains(seen, key->v.Constant.value);
if (in_seen < 0) {
goto error;
}
if (in_seen) {
const char *e = "mapping pattern checks duplicate key (%R)";
compiler_error(c, e, key->v.Constant.value);
goto error;
}
if (PySet_Add(seen, key->v.Constant.value)) {
goto error;
}
}
else if (key->kind != Attribute_kind) {
const char *e = "mapping pattern keys may only match literals and attribute lookups";
return compiler_error(c, e);
compiler_error(c, e);
goto error;
}
if (!compiler_visit_expr(c, key)) {
goto error;
}
VISIT(c, expr, key);
}
// all keys have been checked; there are no duplicates
Py_DECREF(seen);
ADDOP_I(c, BUILD_TUPLE, size);
ADDOP(c, MATCH_KEYS);
// There's now a tuple of keys and a tuple of values on top of the subject:
@ -6224,6 +6257,10 @@ compiler_pattern_mapping(struct compiler *c, pattern_ty p, pattern_context *pc)
pc->on_top--;
ADDOP(c, POP_TOP);
return 1;
error:
Py_DECREF(seen);
return 0;
}
static int