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, 13 insertions, 0 deletions

diff --git a/tests/basics/fun_kwvarargs.py b/tests/basics/fun_kwvarargs.py
index bdc10fcf14..e9fd0720e9 100644
--- a/tests/basics/fun_kwvarargs.py
+++ b/tests/basics/fun_kwvarargs.py
@@ -23,3 +23,16 @@ def f4(*vargs, **kwargs):
 f4(*(1, 2))
 f4(kw_arg=3)
 f4(*(1, 2), kw_arg=3)
+
+
+# test evaluation order of arguments
+def f5(*vargs, **kwargs):
+    print(vargs, kwargs)
+
+
+def print_ret(x):
+    print(x)
+    return x
+
+
+f5(*print_ret(["a", "b"]), kw_arg=print_ret(None))