starlark: disallow keyword argument after *args (#317)
f(*args, k=v) is a now an error. Use f(k=v, *args).
Arguments are evaluated left-to-right, as in Python2 (but not Python3).
See https://github.com/bazelbuild/starlark/issues/13 for spec change.
diff --git a/resolve/resolve.go b/resolve/resolve.go
index 26d74b4..8c1b730 100644
--- a/resolve/resolve.go
+++ b/resolve/resolve.go
@@ -741,7 +741,9 @@
// k=v
n++
if seenKwargs {
- r.errorf(pos, "argument may not follow **kwargs")
+ r.errorf(pos, "keyword argument may not follow **kwargs")
+ } else if seenVarargs {
+ r.errorf(pos, "keyword argument may not follow *args")
}
x := binop.X.(*syntax.Ident)
if seenName[x.Name] {
@@ -757,9 +759,9 @@
// positional argument
p++
if seenVarargs {
- r.errorf(pos, "argument may not follow *args")
+ r.errorf(pos, "positional argument may not follow *args")
} else if seenKwargs {
- r.errorf(pos, "argument may not follow **kwargs")
+ r.errorf(pos, "positional argument may not follow **kwargs")
} else if len(seenName) > 0 {
r.errorf(pos, "positional argument may not follow named")
}
diff --git a/resolve/testdata/resolve.star b/resolve/testdata/resolve.star
index 8399bf3..fb4c78e 100644
--- a/resolve/testdata/resolve.star
+++ b/resolve/testdata/resolve.star
@@ -289,12 +289,12 @@
f(**{}, **{}) ### `multiple \*\*kwargs not allowed`
---
-# Only keyword arguments may follow *args in a call.
+# Only **kwargs may follow *args in a call.
def f(*args, **kwargs):
pass
-f(*[], 1) ### `argument may not follow \*args`
-f(*[], a=1) # ok
+f(*[], 1) ### `positional argument may not follow \*args`
+f(*[], a=1) ### `keyword argument may not follow \*args`
f(*[], *[]) ### `multiple \*args not allowed`
f(*[], **{}) # ok
diff --git a/starlark/eval_test.go b/starlark/eval_test.go
index 00b6e6d..a2d61c5 100644
--- a/starlark/eval_test.go
+++ b/starlark/eval_test.go
@@ -297,6 +297,7 @@
t.Fatal(err)
}
+ // All errors are dynamic; see resolver for static errors.
for _, test := range []struct{ src, want string }{
// a()
{`a()`, `None`},
@@ -352,8 +353,6 @@
{`f(0, b=1)`, `(0, 1, (), {})`},
{`f(0, a=1)`, `function f got multiple values for parameter "a"`},
{`f(0, b=1, c=2)`, `(0, 1, (), {"c": 2})`},
- {`f(0, 1, x=2, *[3, 4], y=5, **dict(z=6))`, // github.com/google/skylark/issues/135
- `(0, 1, (3, 4), {"x": 2, "y": 5, "z": 6})`},
// g(a, b=42, *args, c=123, **kwargs)
{`g()`, `function g missing 1 argument (a)`},
@@ -365,8 +364,6 @@
{`g(0, b=1)`, `(0, 1, (), 123, {})`},
{`g(0, a=1)`, `function g got multiple values for parameter "a"`},
{`g(0, b=1, c=2, d=3)`, `(0, 1, (), 2, {"d": 3})`},
- {`g(0, 1, x=2, *[3, 4], y=5, **dict(z=6))`,
- `(0, 1, (3, 4), 123, {"x": 2, "y": 5, "z": 6})`},
// h(a, b=42, *, c=123, **kwargs)
{`h()`, `function h missing 1 argument (a)`},
@@ -379,7 +376,6 @@
{`h(0, b=1, c=2)`, `(0, 1, 2, {})`},
{`h(0, b=1, d=2)`, `(0, 1, 123, {"d": 2})`},
{`h(0, b=1, c=2, d=3)`, `(0, 1, 2, {"d": 3})`},
- {`h(0, b=1, c=2, d=3)`, `(0, 1, 2, {"d": 3})`},
// i(a, b=42, *, c, d=123, e, **kwargs)
{`i()`, `function i missing 3 arguments (a, c, e)`},
diff --git a/starlark/testdata/function.star b/starlark/testdata/function.star
index a109684..9b74740 100644
--- a/starlark/testdata/function.star
+++ b/starlark/testdata/function.star
@@ -223,20 +223,20 @@
r = []
def id(x):
- r.append(x)
- return x
+ r.append(x)
+ return x
def f(*args, **kwargs):
return (args, kwargs)
-y = f(id(1), id(2), x=id(3), *[id(4)], y=id(5), **dict(z=id(6)))
-assert.eq(y, ((1, 2, 4), dict(x=3, y=5, z=6)))
+y = f(id(1), id(2), x=id(3), *[id(4)], **dict(z=id(5)))
+assert.eq(y, ((1, 2, 4), dict(x=3, z=5)))
-# This matches Python2, but not Starlark-in-Java:
+# This matches Python2 and Starlark-in-Java, but not Python3 [1 2 4 3 6].
# *args and *kwargs are evaluated last.
-# See github.com/bazelbuild/starlark#13 for pending spec change.
-assert.eq(r, [1, 2, 3, 5, 4, 6])
-
+# (Python[23] also allows keyword arguments after *args.)
+# See github.com/bazelbuild/starlark#13 for spec change.
+assert.eq(r, [1, 2, 3, 4, 5])
---
# option:nesteddef option:recursion
