fix: add compile-time check for negative uint2str input (vyperlang#3671)

tests/functional/builtins/codegen/test_uint2str.py

@@ -2,6 +2,9 @@
 
 import pytest
 
+from vyper.compiler import compile_code
+from vyper.exceptions import InvalidType, OverflowException
+
 VALID_BITS = list(range(8, 257, 8))
 
 
@@ -37,3 +40,25 @@ def foo(x: uint{bits}) -> uint256:
     """
     c = get_contract(code)
     assert c.foo(2**bits - 1) == 0, bits
+
+
+def test_bignum_throws():
+    code = """
+@external
+def test():
+    a: String[78] = uint2str(2**256)
+    pass
+    """
+    with pytest.raises(OverflowException):
+        compile_code(code)
+
+
+def test_int_fails():
+    code = """
+@external
+def test():
+    a: String[78] = uint2str(-1)
+    pass
+    """
+    with pytest.raises(InvalidType):
+        compile_code(code)

vyper/builtins/functions.py

@@ -2090,7 +2090,10 @@ def evaluate(self, node):
         if not isinstance(node.args[0], vy_ast.Int):
             raise UnfoldableNode
 
-        value = str(node.args[0].value)
+        value = node.args[0].value
+        if value < 0:
+            raise InvalidType("Only unsigned ints allowed", node)
+        value = str(value)
         return vy_ast.Str.from_node(node, value=value)
 
     def infer_arg_types(self, node):