implement bound= in ranges

tests/functional/semantics/analysis/test_for_loop.py

@@ -1,7 +1,12 @@
 import pytest
 
 from vyper.ast import parse_to_ast
-from vyper.exceptions import ImmutableViolation, TypeMismatch
+from vyper.exceptions import (
+    ArgumentException,
+    ImmutableViolation,
+    StateAccessViolation,
+    TypeMismatch,
+)
 from vyper.semantics.analysis import validate_semantics
 
 
@@ -59,6 +64,34 @@ def bar():
         validate_semantics(vyper_module, {})
 
 
+def test_bad_keywords(namespace):
+    code = """
+
+@internal
+def bar(n: uint256):
+    x: uint256 = 0
+    for i in range(n, boundddd=10):
+        x += i
+    """
+    vyper_module = parse_to_ast(code)
+    with pytest.raises(ArgumentException):
+        validate_semantics(vyper_module, {})
+
+
+def test_bad_bound(namespace):
+    code = """
+
+@internal
+def bar(n: uint256):
+    x: uint256 = 0
+    for i in range(n, bound=n):
+        x += i
+    """
+    vyper_module = parse_to_ast(code)
+    with pytest.raises(StateAccessViolation):
+        validate_semantics(vyper_module, {})
+
+
 def test_modify_iterator_function_call(namespace):
     code = """
 

tests/parser/features/iteration/test_for_range.py

@@ -14,6 +14,23 @@ def repeat(z: int128) -> int128:
     assert c.repeat(9) == 54
 
 
+def test_range_bound(get_contract, assert_tx_failed):
+    code = """
+@external
+def repeat(n: uint256) -> uint256:
+    x: uint256 = 0
+    for i in range(n, bound=6):
+        x += i
+    return x
+    """
+    c = get_contract(code)
+    for n in range(7):
+        assert c.repeat(n) == sum(range(n))
+
+    # check codegen inserts assertion for n greater than bound
+    assert_tx_failed(lambda: c.repeat(7))
+
+
 def test_digit_reverser(get_contract_with_gas_estimation):
     digit_reverser = """
 @external

vyper/codegen/stmt.py

@@ -258,18 +258,25 @@ def _parse_For_range(self):
         arg0 = self.stmt.iter.args[0]
         num_of_args = len(self.stmt.iter.args)
 
+        kwargs = {
+            s.arg: Expr.parse_value_expr(s.value, self.context)
+            for s in self.stmt.iter.keywords or []
+        }
+
         # Type 1 for, e.g. for i in range(10): ...
         if num_of_args == 1:
-            arg0_val = self._get_range_const_value(arg0)
+            n = Expr.parse_value_expr(arg0, self.context)
             start = IRnode.from_list(0, typ=iter_typ)
-            rounds = arg0_val
+            rounds = n
+            rounds_bound = kwargs.get("bound", rounds)
 
         # Type 2 for, e.g. for i in range(100, 110): ...
         elif self._check_valid_range_constant(self.stmt.iter.args[1]).is_literal:
             arg0_val = self._get_range_const_value(arg0)
             arg1_val = self._get_range_const_value(self.stmt.iter.args[1])
             start = IRnode.from_list(arg0_val, typ=iter_typ)
             rounds = IRnode.from_list(arg1_val - arg0_val, typ=iter_typ)
+            rounds_bound = rounds
 
         # Type 3 for, e.g. for i in range(x, x + 10): ...
         else:
@@ -278,9 +285,10 @@ def _parse_For_range(self):
             start = Expr.parse_value_expr(arg0, self.context)
             _, hi = start.typ.int_bounds
             start = clamp("le", start, hi + 1 - rounds)
+            rounds_bound = rounds
 
-        r = rounds if isinstance(rounds, int) else rounds.value
-        if r < 1:
+        bound = rounds_bound if isinstance(rounds_bound, int) else rounds_bound.value
+        if bound < 1:
             return
 
         varname = self.stmt.target.id
@@ -294,7 +302,10 @@ def _parse_For_range(self):
         loop_body.append(["mstore", iptr, i])
         loop_body.append(parse_body(self.stmt.body, self.context))
 
-        ir_node = IRnode.from_list(["repeat", i, start, rounds, rounds, loop_body])
+        # NOTE: codegen for `repeat` inserts an assertion that rounds <= rounds_bound.
+        # if we ever want to remove that, we need to manually add the assertion
+        # where it makes sense.
+        ir_node = IRnode.from_list(["repeat", i, start, rounds, rounds_bound, loop_body])
         del self.context.forvars[varname]
 
         return ir_node

vyper/ir/compile_ir.py

@@ -413,9 +413,8 @@ def _height_of(witharg):
             )
             # stack: i, rounds, rounds_bound
             # assert rounds <= rounds_bound
-            # TODO this runtime assertion should never fail for
+            # TODO this runtime assertion shouldn't fail for
             # internally generated repeats.
-            # maybe drop it or jump to 0xFE
             o.extend(["DUP2", "GT"] + _assert_false())
 
             # stack: i, rounds

vyper/semantics/analysis/annotation.py

@@ -95,6 +95,9 @@ def visit_For(self, node):
             iter_type = node.target._metadata["type"]
             for a in node.iter.args:
                 self.expr_visitor.visit(a, iter_type)
+            for a in node.iter.keywords:
+                if a.arg == "bound":
+                    self.expr_visitor.visit(a.value, iter_type)
 
 
 class ExpressionAnnotationVisitor(_AnnotationVisitorBase):

vyper/semantics/analysis/local.py

@@ -346,17 +346,30 @@ def visit_For(self, node):
                 raise IteratorException(
                     "Cannot iterate over the result of a function call", node.iter
                 )
-            validate_call_args(node.iter, (1, 2))
+            validate_call_args(node.iter, (1, 2), kwargs=["bound"])
 
             args = node.iter.args
+            kwargs = {s.arg: s.value for s in node.iter.keywords or []}
             if len(args) == 1:
                 # range(CONSTANT)
-                if not isinstance(args[0], vy_ast.Num):
-                    raise StateAccessViolation("Value must be a literal", node)
-                if args[0].value <= 0:
-                    raise StructureException("For loop must have at least 1 iteration", args[0])
-                validate_expected_type(args[0], IntegerT.any())
-                type_list = get_possible_types_from_node(args[0])
+                n = args[0]
+                bound = kwargs.pop("bound", None)
+                validate_expected_type(n, IntegerT.any())
+
+                if bound is None:
+                    if not isinstance(n, vy_ast.Num):
+                        raise StateAccessViolation("Value must be a literal", n)
+                    if n.value <= 0:
+                        raise StructureException("For loop must have at least 1 iteration", args[0])
+                    type_list = get_possible_types_from_node(n)
+
+                else:
+                    if not isinstance(bound, vy_ast.Num):
+                        raise StateAccessViolation("bound must be a literal", bound)
+                    if bound.value <= 0:
+                        raise StructureException("bound must be at least 1", args[0])
+                    type_list = get_common_types(n, bound)
+
             else:
                 validate_expected_type(args[0], IntegerT.any())
                 type_list = get_common_types(*args)