fix: raw_call type when max_outsize=0 is set (#3572)

prior to this commit, when `raw_call` is used with `max_outsize`
explicitly set to 0 (`max_outsize=0`) the compiler incorrectly infers that
raw_call has no return type

```vyper
@external
@payable
def foo(_target: address):
    # compiles
    a: bool = raw_call(_target, method_id("foo()"), revert_on_failure=False)
    # should have same behavior, but prior to this commit does not compile:
    b: bool = raw_call(_target, method_id("foo()"), max_outsize=0, revert_on_failure=False)
```

chainsec june 2023 review 5.16

---------

Co-authored-by: tserg <[email protected]>

tests/parser/functions/test_raw_call.py

@@ -1,6 +1,7 @@
 import pytest
 from hexbytes import HexBytes
 
+from vyper import compile_code
 from vyper.builtins.functions import eip1167_bytecode
 from vyper.exceptions import ArgumentException, InvalidType, StateAccessViolation
 
@@ -260,6 +261,68 @@ def __default__():
     w3.eth.send_transaction({"to": caller.address, "data": sig})
 
 
+# check max_outsize=0 does same thing as not setting max_outsize.
+# compile to bytecode and compare bytecode directly.
+def test_max_outsize_0():
+    code1 = """
+@external
+def test_raw_call(_target: address):
+    raw_call(_target, method_id("foo()"))
+    """
+    code2 = """
+@external
+def test_raw_call(_target: address):
+    raw_call(_target, method_id("foo()"), max_outsize=0)
+    """
+    output1 = compile_code(code1, ["bytecode", "bytecode_runtime"])
+    output2 = compile_code(code2, ["bytecode", "bytecode_runtime"])
+    assert output1 == output2
+
+
+# check max_outsize=0 does same thing as not setting max_outsize,
+# this time with revert_on_failure set to False
+def test_max_outsize_0_no_revert_on_failure():
+    code1 = """
+@external
+def test_raw_call(_target: address) -> bool:
+    # compile raw_call both ways, with revert_on_failure
+    a: bool = raw_call(_target, method_id("foo()"), revert_on_failure=False)
+    return a
+    """
+    # same code, but with max_outsize=0
+    code2 = """
+@external
+def test_raw_call(_target: address) -> bool:
+    a: bool = raw_call(_target, method_id("foo()"), max_outsize=0, revert_on_failure=False)
+    return a
+    """
+    output1 = compile_code(code1, ["bytecode", "bytecode_runtime"])
+    output2 = compile_code(code2, ["bytecode", "bytecode_runtime"])
+    assert output1 == output2
+
+
+# test functionality of max_outsize=0
+def test_max_outsize_0_call(get_contract):
+    target_source = """
+@external
+@payable
+def bar() -> uint256:
+    return 123
+    """
+
+    caller_source = """
+@external
+@payable
+def foo(_addr: address) -> bool:
+    success: bool = raw_call(_addr, method_id("bar()"), max_outsize=0, revert_on_failure=False)
+    return success
+    """
+
+    target = get_contract(target_source)
+    caller = get_contract(caller_source)
+    assert caller.foo(target.address) is True
+
+
 def test_static_call_fails_nonpayable(get_contract, assert_tx_failed):
     target_source = """
 baz: int128

vyper/builtins/functions.py

@@ -1093,7 +1093,7 @@ def fetch_call_return(self, node):
         revert_on_failure = kwargz.get("revert_on_failure")
         revert_on_failure = revert_on_failure.value if revert_on_failure is not None else True
 
-        if outsize is None:
+        if outsize is None or outsize.value == 0:
             if revert_on_failure:
                 return None
             return BoolT()