bpo-43892: Make match patterns explicit in the AST (GH-25585)
Co-authored-by: Brandt Bucher <brandtbucher@gmail.com>
diff --git a/Python/symtable.c b/Python/symtable.c
index c6f8694..e620f1e 100644
--- a/Python/symtable.c
+++ b/Python/symtable.c
@@ -214,6 +214,7 @@ static int symtable_implicit_arg(struct symtable *st, int pos);
static int symtable_visit_annotations(struct symtable *st, arguments_ty, expr_ty);
static int symtable_visit_withitem(struct symtable *st, withitem_ty item);
static int symtable_visit_match_case(struct symtable *st, match_case_ty m);
+static int symtable_visit_pattern(struct symtable *st, pattern_ty s);
static identifier top = NULL, lambda = NULL, genexpr = NULL,
@@ -246,7 +247,6 @@ symtable_new(void)
goto fail;
st->st_cur = NULL;
st->st_private = NULL;
- st->in_pattern = 0;
return st;
fail:
_PySymtable_Free(st);
@@ -1676,13 +1676,6 @@ symtable_visit_expr(struct symtable *st, expr_ty e)
VISIT(st, expr, e->v.Slice.step)
break;
case Name_kind:
- // Don't make "_" a local when used in a pattern:
- if (st->in_pattern &&
- e->v.Name.ctx == Store &&
- _PyUnicode_EqualToASCIIString(e->v.Name.id, "_"))
- {
- break;
- }
if (!symtable_add_def(st, e->v.Name.id,
e->v.Name.ctx == Load ? USE : DEF_LOCAL))
VISIT_QUIT(st, 0);
@@ -1702,12 +1695,55 @@ symtable_visit_expr(struct symtable *st, expr_ty e)
case Tuple_kind:
VISIT_SEQ(st, expr, e->v.Tuple.elts);
break;
+ }
+ VISIT_QUIT(st, 1);
+}
+
+static int
+symtable_visit_pattern(struct symtable *st, pattern_ty p)
+{
+ if (++st->recursion_depth > st->recursion_limit) {
+ PyErr_SetString(PyExc_RecursionError,
+ "maximum recursion depth exceeded during compilation");
+ VISIT_QUIT(st, 0);
+ }
+ switch (p->kind) {
+ case MatchValue_kind:
+ VISIT(st, expr, p->v.MatchValue.value);
+ break;
+ case MatchSingleton_kind:
+ /* Nothing to do here. */
+ break;
+ case MatchSequence_kind:
+ VISIT_SEQ(st, pattern, p->v.MatchSequence.patterns);
+ break;
+ case MatchStar_kind:
+ if (p->v.MatchStar.name) {
+ symtable_add_def(st, p->v.MatchStar.name, DEF_LOCAL);
+ }
+ break;
+ case MatchMapping_kind:
+ VISIT_SEQ(st, expr, p->v.MatchMapping.keys);
+ VISIT_SEQ(st, pattern, p->v.MatchMapping.patterns);
+ if (p->v.MatchMapping.rest) {
+ symtable_add_def(st, p->v.MatchMapping.rest, DEF_LOCAL);
+ }
+ break;
+ case MatchClass_kind:
+ VISIT(st, expr, p->v.MatchClass.cls);
+ VISIT_SEQ(st, pattern, p->v.MatchClass.patterns);
+ VISIT_SEQ(st, pattern, p->v.MatchClass.kwd_patterns);
+ break;
case MatchAs_kind:
- VISIT(st, expr, e->v.MatchAs.pattern);
- symtable_add_def(st, e->v.MatchAs.name, DEF_LOCAL);
+ if (p->v.MatchAs.pattern) {
+ VISIT(st, pattern, p->v.MatchAs.pattern);
+ }
+ if (p->v.MatchAs.name) {
+ symtable_add_def(st, p->v.MatchAs.name, DEF_LOCAL);
+ }
break;
case MatchOr_kind:
- VISIT_SEQ(st, expr, e->v.MatchOr.patterns);
+ VISIT_SEQ(st, pattern, p->v.MatchOr.patterns);
break;
}
VISIT_QUIT(st, 1);
@@ -1830,11 +1866,7 @@ symtable_visit_withitem(struct symtable *st, withitem_ty item)
static int
symtable_visit_match_case(struct symtable *st, match_case_ty m)
{
- assert(!st->in_pattern);
- st->in_pattern = 1;
- VISIT(st, expr, m->pattern);
- assert(st->in_pattern);
- st->in_pattern = 0;
+ VISIT(st, pattern, m->pattern);
if (m->guard) {
VISIT(st, expr, m->guard);
}