bpo-32023: Disallow genexprs without parenthesis in class definitions. (#4400)
diff --git a/Doc/whatsnew/3.7.rst b/Doc/whatsnew/3.7.rst
index 82b4840..cbc166d 100644
--- a/Doc/whatsnew/3.7.rst
+++ b/Doc/whatsnew/3.7.rst
@@ -638,10 +638,14 @@
f(1 for x in [1],)
+ class C(1 for x in [1]):
+ pass
+
Python 3.7 now correctly raises a :exc:`SyntaxError`, as a generator
expression always needs to be directly inside a set of parentheses
- and cannot have a comma on either side.
- (Contributed by Serhiy Storchaka in :issue:`32012`.)
+ and cannot have a comma on either side, and the duplication of the
+ parentheses can be omitted only on calls.
+ (Contributed by Serhiy Storchaka in :issue:`32012` and :issue:`32023`.)
Changes in the Python API
diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index c8cb705..e161f56 100644
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -153,6 +153,10 @@
SyntaxError: Generator expression must be parenthesized
>>> f((x for x in L), 1)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+>>> class C(x for x in L):
+... pass
+Traceback (most recent call last):
+SyntaxError: invalid syntax
>>> def g(*args, **kwargs):
... print(args, sorted(kwargs.items()))
diff --git a/Misc/NEWS.d/next/Core and Builtins/2017-11-15-10-49-35.bpo-32023.XnCGT5.rst b/Misc/NEWS.d/next/Core and Builtins/2017-11-15-10-49-35.bpo-32023.XnCGT5.rst
new file mode 100644
index 0000000..d4a8438
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2017-11-15-10-49-35.bpo-32023.XnCGT5.rst
@@ -0,0 +1,3 @@
+SyntaxError is now correctly raised when a generator expression without
+parenthesis is used instead of an inheritance list in a class definition.
+The duplication of the parentheses can be omitted only on calls.
diff --git a/Python/ast.c b/Python/ast.c
index c88e7e3..e44ce51 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -11,6 +11,7 @@
#include "pythonrun.h"
#include <assert.h>
+#include <stdbool.h>
static int validate_stmts(asdl_seq *);
static int validate_exprs(asdl_seq *, expr_context_ty, int);
@@ -611,7 +612,7 @@
static stmt_ty ast_for_for_stmt(struct compiling *, const node *, int);
/* Note different signature for ast_for_call */
-static expr_ty ast_for_call(struct compiling *, const node *, expr_ty);
+static expr_ty ast_for_call(struct compiling *, const node *, expr_ty, bool);
static PyObject *parsenumber(struct compiling *, const char *);
static expr_ty parsestrplus(struct compiling *, const node *n);
@@ -1545,7 +1546,7 @@
name_expr = NULL;
}
else {
- d = ast_for_call(c, CHILD(n, 3), name_expr);
+ d = ast_for_call(c, CHILD(n, 3), name_expr, true);
if (!d)
return NULL;
name_expr = NULL;
@@ -2368,7 +2369,7 @@
return Call(left_expr, NULL, NULL, LINENO(n),
n->n_col_offset, c->c_arena);
else
- return ast_for_call(c, CHILD(n, 1), left_expr);
+ return ast_for_call(c, CHILD(n, 1), left_expr, true);
}
else if (TYPE(CHILD(n, 0)) == DOT) {
PyObject *attr_id = NEW_IDENTIFIER(CHILD(n, 1));
@@ -2705,7 +2706,7 @@
}
static expr_ty
-ast_for_call(struct compiling *c, const node *n, expr_ty func)
+ast_for_call(struct compiling *c, const node *n, expr_ty func, bool allowgen)
{
/*
arglist: argument (',' argument)* [',']
@@ -2728,6 +2729,10 @@
nargs++;
else if (TYPE(CHILD(ch, 1)) == comp_for) {
nargs++;
+ if (!allowgen) {
+ ast_error(c, ch, "invalid syntax");
+ return NULL;
+ }
if (NCH(n) > 1) {
ast_error(c, ch, "Generator expression must be parenthesized");
return NULL;
@@ -3973,7 +3978,7 @@
if (!dummy_name)
return NULL;
dummy = Name(dummy_name, Load, LINENO(n), n->n_col_offset, c->c_arena);
- call = ast_for_call(c, CHILD(n, 3), dummy);
+ call = ast_for_call(c, CHILD(n, 3), dummy, false);
if (!call)
return NULL;
}