[mypyc] Implement str-to-float primitive (#9685)

related mypyc/mypyc#644

Implement builtins.float conversion from strings.

mypyc/primitives/float_ops.py

@@ -0,0 +1,17 @@
+"""Primitive float ops."""
+
+from mypyc.ir.ops import ERR_MAGIC
+from mypyc.ir.rtypes import (
+    str_rprimitive, float_rprimitive
+)
+from mypyc.primitives.registry import (
+    c_function_op
+)
+
+# float(str)
+c_function_op(
+    name='builtins.float',
+    arg_types=[str_rprimitive],
+    return_type=float_rprimitive,
+    c_function_name='PyFloat_FromString',
+    error_kind=ERR_MAGIC)

mypyc/primitives/registry.py

@@ -345,3 +345,4 @@ def load_address_op(name: str,
 import mypyc.primitives.dict_ops  # noqa
 import mypyc.primitives.tuple_ops  # noqa
 import mypyc.primitives.misc_ops  # noqa
+import mypyc.primitives.float_ops  # noqa

mypyc/test-data/run-floats.test

@@ -0,0 +1,12 @@
+[case testStrToFloat]
+def str_to_float(x: str) -> float:
+    return float(x)
+
+[file driver.py]
+from native import str_to_float
+
+assert str_to_float("1") == 1.0
+assert str_to_float("1.234567") == 1.234567
+assert str_to_float("44324") == 44324.0
+assert str_to_float("23.4") == 23.4
+assert str_to_float("-43.44e-4") == -43.44e-4

mypyc/test/test_run.py

@@ -33,6 +33,7 @@
     'run-misc.test',
     'run-functions.test',
     'run-integers.test',
+    'run-floats.test',
     'run-bools.test',
     'run-strings.test',
     'run-tuples.test',