Fix for SF [ 734869 ] Lambda functions in list comprehensions

The compiler was reseting the list comprehension tmpname counter for each function, but the symtable was using the same counter for the entire module.  Repair by move tmpname into the symtable entry.

Bugfix candidate.

2 files changed, 24 insertions, 14 deletions

diff --git a/Python/compile.c b/Python/compile.c
index a98b905fd6..76a3711510 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -731,6 +731,7 @@ static void symtable_global(struct symtable *, node *);
 static void symtable_import(struct symtable *, node *);
 static void symtable_assign(struct symtable *, node *, int);
 static void symtable_list_comprehension(struct symtable *, node *);
+static void symtable_list_for(struct symtable *, node *);
 
 static int symtable_update_free_vars(struct symtable *);
 static int symtable_undo_free(struct symtable *, PyObject *, PyObject *);
@@ -1602,6 +1603,8 @@ com_list_comprehension(struct compiling *c, node *n)
 {
 	/* listmaker: test list_for */
 	char tmpname[30];
+
+	REQ(n, listmaker);
 	PyOS_snprintf(tmpname, sizeof(tmpname), "_[%d]", ++c->c_tmpname);
 	com_addoparg(c, BUILD_LIST, 0);
 	com_addbyte(c, DUP_TOP); /* leave the result on the stack */
@@ -4921,7 +4924,6 @@ symtable_init()
 	st->st_cur = NULL;
 	st->st_nscopes = 0;
 	st->st_errors = 0;
-	st->st_tmpname = 0;
 	st->st_private = NULL;
 	return st;
  fail:
@@ -5123,9 +5125,6 @@ symtable_enter_scope(struct symtable *st, char *name, int type,
 	if (st->st_cur) {
 		prev = st->st_cur;
 		if (PyList_Append(st->st_stack, (PyObject *)st->st_cur) < 0) {
-			/* Py_DECREF(st->st_cur); */
-			/* I believe the previous line would lead to a
-			   double-DECREF when st is disposed - JRH */
 			st->st_errors++;
 			return;
 		}
@@ -5395,12 +5394,12 @@ symtable_node(struct symtable *st, node *n)
 		}
 		goto loop;
 	case list_iter:
+		/* only occurs when there are multiple for loops
+		   in a list comprehension */
 		n = CHILD(n, 0);
-		if (TYPE(n) == list_for) {
-			st->st_tmpname++;
-			symtable_list_comprehension(st, n);
-			st->st_tmpname--;
-		} else {
+		if (TYPE(n) == list_for)
+			symtable_list_for(st, n);
+		else {
 			REQ(n, list_if);
 			symtable_node(st, CHILD(n, 1));
 			if (NCH(n) == 3) {
@@ -5428,10 +5427,7 @@ symtable_node(struct symtable *st, node *n)
 		/* fall through */
 	case listmaker:
 		if (NCH(n) > 1 && TYPE(CHILD(n, 1)) == list_for) {
-			st->st_tmpname++;
-			symtable_list_comprehension(st, CHILD(n, 1));
-			symtable_node(st, CHILD(n, 0));
-			st->st_tmpname--;
+			symtable_list_comprehension(st, n);
 			break;
 		}
 		/* fall through */
@@ -5629,10 +5625,23 @@ symtable_global(struct symtable *st, node *n)
 static void
 symtable_list_comprehension(struct symtable *st, node *n)
 {
+	/* listmaker: test list_for */
 	char tmpname[30];
 
-	PyOS_snprintf(tmpname, sizeof(tmpname), "_[%d]", st->st_tmpname);
+	REQ(n, listmaker);
+	PyOS_snprintf(tmpname, sizeof(tmpname), "_[%d]", 
+		      ++st->st_cur->ste_tmpname);
 	symtable_add_def(st, tmpname, DEF_LOCAL);
+	symtable_list_for(st, CHILD(n, 1));
+	symtable_node(st, CHILD(n, 0));
+	--st->st_cur->ste_tmpname;
+}
+
+static void
+symtable_list_for(struct symtable *st, node *n)
+{
+	REQ(n, list_for);
+	/* list_for: for v in expr [list_iter] */
 	symtable_assign(st, CHILD(n, 1), 0);
 	symtable_node(st, CHILD(n, 3));
 	if (NCH(n) == 5)
diff --git a/Python/symtable.c b/Python/symtable.c
index e48eaea1d5..f86fd2fbc8 100644
--- a/Python/symtable.c
+++ b/Python/symtable.c
@@ -61,6 +61,7 @@ PySymtableEntry_New(struct symtable *st, char *name, int type, int lineno)
 
 	ste->ste_optimized = 0;
 	ste->ste_opt_lineno = 0;
+	ste->ste_tmpname = 0;
 	ste->ste_lineno = lineno;
 	switch (type) {
 	case funcdef: