fix[lang]: use folded node for typechecking (#4365)

This commit addresses several issues in the frontend where valid code
fails to compile because typechecking was performed on non-literal
AST nodes, specifically in `slice()` and `raw_log()` builtins. This is
fixed by using the folded node for typechecking instead.

Additionally, folding is applied for the argument to `convert()`, which
results in the typechecker being able to reject more invalid programs.

tests/functional/codegen/features/test_logging.py

@@ -1254,6 +1254,23 @@ def foo():
     assert log.topics == [event_id, topic1, topic2, topic3]
 
 
+valid_list = [
+    # test constant folding inside raw_log
+    """
+topic: constant(bytes32) = 0x1212121212121210212801291212121212121210121212121212121212121212
+
+@external
+def foo():
+    raw_log([[topic]][0], b'')
+    """
+]
+
+
+@pytest.mark.parametrize("code", valid_list)
+def test_raw_log_pass(code):
+    assert compile_code(code) is not None
+
+
 fail_list = [
     (
         """

tests/functional/syntax/exceptions/test_invalid_literal_exception.py

@@ -36,6 +36,14 @@ def foo():
 def foo():
     a: bytes32 = keccak256("ѓtest")
     """,
+    # test constant folding inside of `convert()`
+    """
+BAR: constant(uint16) = 256
+
+@external
+def foo():
+    a: uint8 = convert(BAR, uint8)
+    """,
 ]
 
 

tests/functional/syntax/exceptions/test_type_mismatch_exception.py

@@ -47,6 +47,14 @@ def foo():
     """
 a: constant(address) = 0x3cd751e6b0078be393132286c442345e5dc49699
     """,
+    # test constant folding inside `convert()`
+    """
+BAR: constant(Bytes[5]) = b"vyper"
+
+@external
+def foo():
+    a: Bytes[4] = convert(BAR, Bytes[4])
+    """,
 ]
 
 

tests/functional/syntax/test_slice.py

@@ -53,6 +53,22 @@ def foo(inp: Bytes[10]) -> Bytes[4]:
 def foo() -> Bytes[10]:
     return slice(b"badmintonzzz", 1, 10)
     """,
+    # test constant folding for `slice()` `length` argument
+    """
+@external
+def foo():
+    x: Bytes[32] = slice(msg.data, 0, 31 + 1)
+    """,
+    """
+@external
+def foo(a: address):
+    x: Bytes[32] = slice(a.code, 0, 31 + 1)
+    """,
+    """
+@external
+def foo(inp: Bytes[5], start: uint256) -> Bytes[3]:
+    return slice(inp, 0, 1 + 1)
+    """,
 ]
 
 

vyper/builtins/_convert.py

@@ -463,7 +463,7 @@ def to_flag(expr, arg, out_typ):
 def convert(expr, context):
     assert len(expr.args) == 2, "bad typecheck: convert"
 
-    arg_ast = expr.args[0]
+    arg_ast = expr.args[0].reduced()
     arg = Expr(arg_ast, context).ir_node
     original_arg = arg
 

vyper/builtins/functions.py

@@ -305,7 +305,7 @@ def fetch_call_return(self, node):
 
         arg = node.args[0]
         start_expr = node.args[1]
-        length_expr = node.args[2]
+        length_expr = node.args[2].reduced()
 
         # CMC 2022-03-22 NOTE slight code duplication with semantics/analysis/local
         is_adhoc_slice = arg.get("attr") == "code" or (
@@ -1257,7 +1257,8 @@ def fetch_call_return(self, node):
     def infer_arg_types(self, node, expected_return_typ=None):
         self._validate_arg_types(node)
 
-        if not isinstance(node.args[0], vy_ast.List) or len(node.args[0].elements) > 4:
+        arg = node.args[0].reduced()
+        if not isinstance(arg, vy_ast.List) or len(arg.elements) > 4:
             raise InvalidType("Expecting a list of 0-4 topics as first argument", node.args[0])
 
         # return a concrete type for `data`
@@ -1269,7 +1270,7 @@ def infer_arg_types(self, node, expected_return_typ=None):
     def build_IR(self, expr, args, kwargs, context):
         context.check_is_not_constant(f"use {self._id}", expr)
 
-        topics_length = len(expr.args[0].elements)
+        topics_length = len(expr.args[0].reduced().elements)
         topics = args[0].args
         topics = [unwrap_location(topic) for topic in topics]
 

vyper/semantics/analysis/local.py

@@ -136,7 +136,7 @@ def _validate_address_code(node: vy_ast.Attribute, value_type: VyperType) -> Non
         parent = node.get_ancestor()
         if isinstance(parent, vy_ast.Call):
             ok_func = isinstance(parent.func, vy_ast.Name) and parent.func.id == "slice"
-            ok_args = len(parent.args) == 3 and isinstance(parent.args[2], vy_ast.Int)
+            ok_args = len(parent.args) == 3 and isinstance(parent.args[2].reduced(), vy_ast.Int)
             if ok_func and ok_args:
                 return
 
@@ -154,7 +154,7 @@ def _validate_msg_data_attribute(node: vy_ast.Attribute) -> None:
                 "msg.data is only allowed inside of the slice, len or raw_call functions", node
             )
         if parent.get("func.id") == "slice":
-            ok_args = len(parent.args) == 3 and isinstance(parent.args[2], vy_ast.Int)
+            ok_args = len(parent.args) == 3 and isinstance(parent.args[2].reduced(), vy_ast.Int)
             if not ok_args:
                 raise StructureException(
                     "slice(msg.data) must use a compile-time constant for length argument", parent