Disallow f(x, y=1, z) and similar nonsense
Python rejects such function definitions because it doesn't make much
sense to have arguments with no default values after arguments with
default values.
Jinja did allow them, but handled them improperly (associating the
default value with the wrong argument).
Due to how broken the current behavior is, it makes more sense to reject
templates containing such defintions instead of trying to handle them
properly. Both cases are going to break existing code containing such
definitions, but besides the fact that possibly no such code exists it
is better to fail with a clear error than to silently change the values
of arguments.
This fixes #364
diff --git a/CHANGES b/CHANGES
index ffe0a92..eaa6e6b 100644
--- a/CHANGES
+++ b/CHANGES
@@ -21,6 +21,10 @@
- Implemented a block ``set`` tag.
- Default cache size was incrased to 400 from a low 50.
- Fixed ``is number`` test to accept long integers in all Python versions.
+- Added a check for default arguments followed by non-default arguments. This
+ change makes ``{% macro m(x, y=1, z) %}...{% endmacro %}`` a syntax error. The
+ previous behavior for this code was broken anyway (resulting in the default
+ value being applied to `y`).
Version 2.7.3
-------------
diff --git a/jinja2/parser.py b/jinja2/parser.py
index 2cf2bd2..d24da18 100644
--- a/jinja2/parser.py
+++ b/jinja2/parser.py
@@ -314,6 +314,8 @@
arg.set_ctx('param')
if self.stream.skip_if('assign'):
defaults.append(self.parse_expression())
+ elif defaults:
+ self.fail('non-default argument follows default argument')
args.append(arg)
self.stream.expect('rparen')
diff --git a/jinja2/testsuite/core_tags.py b/jinja2/testsuite/core_tags.py
index ac0eb4c..e1cff3b 100644
--- a/jinja2/testsuite/core_tags.py
+++ b/jinja2/testsuite/core_tags.py
@@ -244,6 +244,15 @@
{{ m() }}|{{ m('a') }}|{{ m('a', 'b') }}|{{ m(1, 2, 3) }}''')
assert tmpl.render() == '||c|d|a||c|d|a|b|c|d|1|2|3|d'
+ def test_arguments_defaults_nonsense(self):
+ self.assert_raises(TemplateSyntaxError, self.env.from_string, '''\
+{% macro m(a, b=1, c) %}a={{ a }}, b={{ b }}, c={{ c }}{% endmacro %}''')
+
+ def test_caller_defaults_nonsense(self):
+ self.assert_raises(TemplateSyntaxError, self.env.from_string, '''\
+{% macro a() %}{{ caller() }}{% endmacro %}
+{% call(x, y=1, z) a() %}{% endcall %}''')
+
def test_varargs(self):
tmpl = self.env.from_string('''\
{% macro test() %}{{ varargs|join('|') }}{% endmacro %}\
