feat[lang]!: change ABI type of decimal to int168 (#3696)

this commit changes how decimals are exposed in the ABI - changing
the ABI type from `fixed168x10` to `int168`. this is done for
compatibility reaosns, since `fixedMxN` types are not widely supported.
it is also a preparatory breaking change for supporting more decimal
types, in the future, we might expand the set of decimal types, e.g.
something along the lines of `Decimal[bits, places]`. in such a future,
if we add `UDecimal[256, 18]` (colloquially known as `"wad"`), it would
be useful to users if it had an ABI type of uint256, for compatibility
with common ERCs.

to distinguish from plain `int168` in the JSON ABI, an `"internalType"`
field is added, which includes the decimal info. in the future, if we
add more decimal types, it would be distinguished from other decimal
types according to the metadata, ex.:
`{"internalType": {"decimal": {"bits": 168, "places": 10}}}`.

misc/refactor:
- remove `FixedMxN` abi types
- add a `decimal_to_int()` utility function to make test migration
  cleaner. it essentially emulates what the compiler does internally during
  codegen, which is that it takes the arguments to a `Decimal` and then
  bitcasts the resulting `Decimal` to an int.

---------

Co-authored-by: tserg <8017125+tserg@users.noreply.github.com>

docs/types.rst

@@ -239,7 +239,7 @@ A value with a precision of 10 decimal places between -1870722095783555735300716
 
 In order for a literal to be interpreted as ``decimal`` it must include a decimal point.
 
-The ABI type (for computing method identifiers) of ``decimal`` is ``fixed168x10``.
+The ABI type (for computing method identifiers) of ``decimal`` is ``int168``.
 
 Operators
 *********

tests/functional/builtins/codegen/test_abi_decode.py

@@ -1,8 +1,7 @@
-from decimal import Decimal
-
 import pytest
 from eth.codecs import abi
 
+from tests.utils import decimal_to_int
 from vyper.exceptions import ArgumentException, StackTooDeep, StructureException
 
 TEST_ADDR = "0x" + b"".join(chr(i).encode("utf-8") for i in range(20)).hex()
@@ -54,22 +53,28 @@ def abi_decode_struct(x: Bytes[544]) -> Human:
     c = get_contract(contract)
 
     test_bytes32 = b"".join(chr(i).encode("utf-8") for i in range(32))
-    args = (TEST_ADDR, -1, True, Decimal("-123.4"), test_bytes32)
-    encoding = "(address,int128,bool,fixed168x10,bytes32)"
+    args = (TEST_ADDR, -1, True, decimal_to_int("-123.4"), test_bytes32)
+    encoding = "(address,int128,bool,int168,bytes32)"
     encoded = abi.encode(encoding, args)
-    assert tuple(c.abi_decode(encoded)) == (TEST_ADDR, -1, True, Decimal("-123.4"), test_bytes32)
+    assert tuple(c.abi_decode(encoded)) == (
+        TEST_ADDR,
+        -1,
+        True,
+        decimal_to_int("-123.4"),
+        test_bytes32,
+    )
 
     test_bytes32 = b"".join(chr(i).encode("utf-8") for i in range(32))
     human_tuple = (
         "foobar",
-        ("vyper", TEST_ADDR, 123, True, Decimal("123.4"), [123, 456, 789], test_bytes32),
+        ("vyper", TEST_ADDR, 123, True, decimal_to_int("123.4"), [123, 456, 789], test_bytes32),
     )
     args = tuple([human_tuple[0]] + list(human_tuple[1]))
-    human_t = "((string,(string,address,int128,bool,fixed168x10,uint256[3],bytes32)))"
+    human_t = "((string,(string,address,int128,bool,int168,uint256[3],bytes32)))"
     human_encoded = abi.encode(human_t, (human_tuple,))
     assert tuple(c.abi_decode_struct(human_encoded)) == (
         "foobar",
-        ("vyper", TEST_ADDR, 123, True, Decimal("123.4"), [123, 456, 789], test_bytes32),
+        ("vyper", TEST_ADDR, 123, True, decimal_to_int("123.4"), [123, 456, 789], test_bytes32),
     )
 
 

tests/functional/builtins/codegen/test_abi_encode.py

@@ -1,8 +1,7 @@
-from decimal import Decimal
-
 import pytest
 from eth.codecs import abi
 
+from tests.utils import decimal_to_int
 from vyper.exceptions import StackTooDeep
 
 
@@ -109,10 +108,10 @@ def abi_encode3(x: uint256, ensure_tuple: bool, include_method_id: bool) -> Byte
     test_bytes32 = b"".join(chr(i).encode("utf-8") for i in range(32))
     human_tuple = (
         "foobar",
-        ("vyper", test_addr, 123, True, Decimal("123.4"), [123, 456, 789], test_bytes32),
+        ("vyper", test_addr, 123, True, decimal_to_int("123.4"), [123, 456, 789], test_bytes32),
     )
     args = tuple([human_tuple[0]] + list(human_tuple[1]))
-    human_t = "(string,(string,address,int128,bool,fixed168x10,uint256[3],bytes32))"
+    human_t = "(string,(string,address,int128,bool,int168,uint256[3],bytes32))"
     human_encoded = abi.encode(human_t, human_tuple)
     assert c.abi_encode(*args, False, False).hex() == human_encoded.hex()
     assert c.abi_encode(*args, False, True).hex() == (method_id + human_encoded).hex()

tests/functional/builtins/codegen/test_as_wei_value.py

@@ -1,7 +1,9 @@
-from decimal import Decimal
-
 import pytest
 
+from tests.utils import decimal_to_int
+from vyper.semantics.types import DecimalT
+from vyper.utils import quantize, round_towards_zero
+
 wei_denoms = {
     "femtoether": 3,
     "kwei": 3,
@@ -61,11 +63,14 @@ def test_wei_decimal(get_contract, tx_failed, denom, multiplier):
 def foo(a: decimal) -> uint256:
     return as_wei_value(a, "{denom}")
     """
-
     c = get_contract(code)
-    value = Decimal((2**127 - 1) / (10**multiplier))
 
-    assert c.foo(value) == value * (10**multiplier)
+    denom_int = 10**multiplier
+    # TODO: test with more values
+    _, hi = DecimalT().ast_bounds
+    value = quantize(hi / denom_int)
+
+    assert c.foo(decimal_to_int(value)) == round_towards_zero(value * denom_int)
 
 
 @pytest.mark.parametrize("value", (-1, -(2**127)))

tests/functional/builtins/codegen/test_ceil.py

@@ -1,6 +1,8 @@
 import math
 from decimal import Decimal
 
+from tests.utils import decimal_to_int
+
 
 def test_ceil(get_contract_with_gas_estimation):
     code = """
@@ -102,8 +104,8 @@ def ceil_param(p: decimal) -> int256:
     assert c.fos() == -5472
     assert c.fot() == math.ceil(-(Decimal(2**167 - 1)) / 10**10)
     assert c.fou() == -3
-    assert c.ceil_param(Decimal("-0.5")) == 0
-    assert c.ceil_param(Decimal("-7777777.7777777")) == -7777777
+    assert c.ceil_param(decimal_to_int("-0.5")) == 0
+    assert c.ceil_param(decimal_to_int("-7777777.7777777")) == -7777777
 
 
 def test_ceil_ext_call(w3, side_effects_contract, assert_side_effects_invoked, get_contract):

tests/functional/builtins/codegen/test_convert.py

@@ -1,13 +1,13 @@
 import enum
 import itertools
-
-# import random
+import math
 from decimal import Decimal
 
 import eth.codecs.abi as abi
 import eth.codecs.abi.exceptions
 import pytest
 
+from tests.utils import decimal_to_int
 from vyper.compiler import compile_code
 from vyper.exceptions import InvalidLiteral, InvalidType, TypeMismatch
 from vyper.semantics.types import AddressT, BoolT, BytesM_T, BytesT, DecimalT, IntegerT, StringT
@@ -249,13 +249,20 @@ def _padconvert(val_bits, direction, n, padding_byte=None):
 def _from_bits(val_bits, o_typ):
     # o_typ: the type to convert to
     try:
-        return abi.decode(o_typ.abi_type.selector_name(), val_bits)
+        ret = abi.decode(o_typ.abi_type.selector_name(), val_bits)
+        if isinstance(o_typ, DecimalT):
+            return Decimal(ret) / o_typ.divisor
+        return ret
     except eth.codecs.abi.exceptions.DecodeError:
         raise _OutOfBounds() from None
 
 
 def _to_bits(val, i_typ):
     # i_typ: the type to convert from
+    if isinstance(i_typ, DecimalT):
+        val = val * i_typ.divisor
+        assert math.ceil(val) == math.floor(val)
+        val = int(val)
     return abi.encode(i_typ.abi_type.selector_name(), val)
 
 
@@ -430,6 +437,13 @@ def test_convert_passing(
         # web3 has special formatter for zero address
         expected_val = None
 
+    if isinstance(o_typ, DecimalT):
+        expected_val = decimal_to_int(expected_val)
+
+    input_val = val
+    if isinstance(i_typ, DecimalT):
+        input_val = decimal_to_int(val)
+
     contract_1 = f"""
 @external
 def test_convert() -> {o_typ}:
@@ -461,7 +475,7 @@ def test_input_convert(x: {i_typ}) -> {o_typ}:
     """
 
     c2 = get_contract_with_gas_estimation(contract_2)
-    assert c2.test_input_convert(val) == expected_val
+    assert c2.test_input_convert(input_val) == expected_val
 
     contract_3 = f"""
 bar: {i_typ}
@@ -483,7 +497,7 @@ def test_memory_variable_convert(x: {i_typ}) -> {o_typ}:
     """
 
     c4 = get_contract_with_gas_estimation(contract_4)
-    assert c4.test_memory_variable_convert(val) == expected_val
+    assert c4.test_memory_variable_convert(input_val) == expected_val
 
 
 @pytest.mark.parametrize("typ", ["uint8", "int128", "int256", "uint256"])
@@ -715,5 +729,8 @@ def foo(bar: {i_typ}) -> {o_typ}:
     """
 
     c3 = get_contract_with_gas_estimation(contract_3)
+    input_val = val
+    if isinstance(i_typ, DecimalT):
+        input_val = decimal_to_int(input_val)
     with tx_failed():
-        c3.foo(val)
+        c3.foo(input_val)

tests/functional/builtins/codegen/test_floor.py

@@ -1,6 +1,8 @@
 import math
 from decimal import Decimal
 
+from tests.utils import decimal_to_int
+
 
 def test_floor(get_contract_with_gas_estimation):
     code = """
@@ -106,8 +108,8 @@ def floor_param(p: decimal) -> int256:
     assert c.fos() == -1
     assert c.fot() == math.floor(-Decimal(2**167) / 10**10)
     assert c.fou() == -4
-    assert c.floor_param(Decimal("-5.6")) == -6
-    assert c.floor_param(Decimal("-0.0000000001")) == -1
+    assert c.floor_param(decimal_to_int("-5.6")) == -6
+    assert c.floor_param(decimal_to_int("-0.0000000001")) == -1
 
 
 def test_floor_ext_call(w3, side_effects_contract, assert_side_effects_invoked, get_contract):

tests/functional/builtins/codegen/test_minmax.py

@@ -1,7 +1,6 @@
-from decimal import Decimal
-
 import pytest
 
+from tests.utils import decimal_to_int
 from vyper.semantics.types import IntegerT
 
 
@@ -17,7 +16,7 @@ def goo() -> uint256:
     """
 
     c = get_contract_with_gas_estimation(minmax_test)
-    assert c.foo() == Decimal("58223.123")
+    assert c.foo() == decimal_to_int("58223.123")
     assert c.goo() == 83
 
     print("Passed min/max test")

tests/functional/builtins/codegen/test_minmax_value.py

@@ -15,7 +15,7 @@ def foo() -> {typ}:
     """
     c = get_contract(code)
 
-    lo, hi = typ.ast_bounds
+    lo, hi = typ.int_bounds
     if op == "min_value":
         assert c.foo() == lo
     elif op == "max_value":

tests/functional/builtins/codegen/test_unary.py

@@ -1,7 +1,6 @@
-from decimal import Decimal
-
 import pytest
 
+from tests.utils import decimal_to_int
 from vyper.exceptions import InvalidOperation
 
 
@@ -63,8 +62,8 @@ def bar() -> decimal:
     """
 
     c = get_contract(code)
-    assert c.foo() == Decimal("-18707220957835557353007165858768422651595.9365500927")
-    assert c.bar() == Decimal("18707220957835557353007165858768422651595.9365500927")
+    assert c.foo() == decimal_to_int("-18707220957835557353007165858768422651595.9365500927")
+    assert c.bar() == decimal_to_int("18707220957835557353007165858768422651595.9365500927")
 
 
 def test_negation_int128(get_contract):

tests/functional/builtins/folding/test_epsilon.py

@@ -1,6 +1,6 @@
 import pytest
 
-from tests.utils import parse_and_fold
+from tests.utils import decimal_to_int, parse_and_fold
 
 
 @pytest.mark.parametrize("typ_name", ["decimal"])
@@ -16,4 +16,4 @@ def foo() -> {typ_name}:
     old_node = vyper_ast.body[0].value
     new_node = old_node.get_folded_value()
 
-    assert contract.foo() == new_node.value
+    assert contract.foo() == decimal_to_int(new_node.value)

tests/functional/builtins/folding/test_floor_ceil.py

@@ -4,7 +4,7 @@
 from hypothesis import example, given, settings
 from hypothesis import strategies as st
 
-from tests.utils import parse_and_fold
+from tests.utils import decimal_to_int, parse_and_fold
 
 st_decimals = st.decimals(
     min_value=-(2**32), max_value=2**32, allow_nan=False, allow_infinity=False, places=10
@@ -31,4 +31,5 @@ def foo(a: decimal) -> int256:
     old_node = vyper_ast.body[0].value
     new_node = old_node.get_folded_value()
 
-    assert contract.foo(value) == new_node.value
+    assert isinstance(new_node.value, int)
+    assert contract.foo(decimal_to_int(value)) == new_node.value

tests/functional/builtins/folding/test_fold_as_wei_value.py

@@ -2,7 +2,7 @@
 from hypothesis import given, settings
 from hypothesis import strategies as st
 
-from tests.utils import parse_and_fold
+from tests.utils import decimal_to_int, parse_and_fold
 from vyper.builtins import functions as vy_fn
 from vyper.utils import SizeLimits
 
@@ -34,7 +34,8 @@ def foo(a: decimal) -> uint256:
     old_node = vyper_ast.body[0].value
     new_node = old_node.get_folded_value()
 
-    assert contract.foo(value) == new_node.value
+    assert isinstance(new_node.value, int)
+    assert contract.foo(decimal_to_int(value)) == new_node.value
 
 
 @pytest.mark.fuzzing

tests/functional/builtins/folding/test_min_max.py

@@ -2,7 +2,7 @@
 from hypothesis import given, settings
 from hypothesis import strategies as st
 
-from tests.utils import parse_and_fold
+from tests.utils import decimal_to_int, parse_and_fold
 from vyper.utils import SizeLimits
 
 st_decimals = st.decimals(
@@ -32,7 +32,8 @@ def foo(a: decimal, b: decimal) -> decimal:
     old_node = vyper_ast.body[0].value
     new_node = old_node.get_folded_value()
 
-    assert contract.foo(left, right) == new_node.value
+    l, r = [decimal_to_int(t) for t in (left, right)]
+    assert contract.foo(l, r) == decimal_to_int(new_node.value)
 
 
 @pytest.mark.fuzzing

tests/functional/codegen/calling_convention/test_external_contract_calls.py

@@ -1,8 +1,7 @@
-from decimal import Decimal
-
 import pytest
 from eth.codecs import abi
 
+from tests.utils import decimal_to_int
 from vyper import compile_code
 from vyper.exceptions import (
     ArgumentException,
@@ -517,7 +516,7 @@ def bar(arg1: address) -> decimal:
 """
 
     c2 = get_contract(contract_2)
-    assert c2.bar(c.address) == Decimal("1e-10")
+    assert c2.bar(c.address) == decimal_to_int("1e-10")
 
 
 def test_decimal_too_long(get_contract, tx_failed):
@@ -570,7 +569,7 @@ def bar(arg1: address) -> (decimal, Bytes[3], decimal):
     c2 = get_contract(contract_2)
     assert c.foo() == [0, b"dog", 1]
     result = c2.bar(c.address)
-    assert result == [Decimal("0.0"), b"dog", Decimal("1e-10")]
+    assert result == [decimal_to_int("0.0"), b"dog", decimal_to_int("1e-10")]
 
 
 @pytest.mark.parametrize("a,b", [(8, 256), (256, 8), (256, 256)])