py/runtime: Allow multiple *args in a function call.

This is a partial implementation of PEP 448 to allow unpacking multiple
star args in a function or method call.

This is implemented by changing the emitted bytecodes so that both
positional args and star args are stored as positional args.  A bitmap is
added to indicate if an argument at a given position is a positional
argument or a star arg.

In the generated code, this new bitmap takes the place of the old star arg.
It is stored as a small int, so this means only the first N arguments can
be star args where N is the number of bits in a small int.

The runtime is modified to interpret this new bytecode format while still
trying to perform as few memory reallocations as possible.

Signed-off-by: David Lechner <david@pybricks.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/tests/basics/fun_callstardblstar.py b/tests/basics/fun_callstardblstar.py
index f2fd29107..aceb04a84 100644
--- a/tests/basics/fun_callstardblstar.py
+++ b/tests/basics/fun_callstardblstar.py
@@ -6,6 +6,11 @@ def f(a, b, c, d):
 f(*(1, 2), **{'c':3, 'd':4})
 f(*(1, 2), **{['c', 'd'][i]:(3 + i) for i in range(2)})
 
+try:
+    eval("f(**{'a': 1}, *(2, 3, 4))")
+except SyntaxError:
+    print("SyntaxError")
+
 # test calling a method with *tuple and **dict
 
 class A:
@@ -15,3 +20,8 @@ class A:
 a = A()
 a.f(*(1, 2), **{'c':3, 'd':4})
 a.f(*(1, 2), **{['c', 'd'][i]:(3 + i) for i in range(2)})
+
+try:
+    eval("a.f(**{'a': 1}, *(2, 3, 4))")
+except SyntaxError:
+    print("SyntaxError")