fix: add safe transfer

Author: igorroncevic

src/types/ComposableCowPoller.sol

@@ -2,12 +2,15 @@
 pragma solidity >=0.8.0 <0.9.0;
 
 import {IERC20, GPv2Order} from "cowprotocol/contracts/libraries/GPv2Order.sol";
+import {GPv2SafeERC20} from "cowprotocol/contracts/libraries/GPv2SafeERC20.sol";
 
 import {ComposableCoW} from "src/ComposableCoW.sol";
 import {IConditionalOrder, IConditionalOrderGenerator} from "src/interfaces/IConditionalOrder.sol";
 
 /// @title ComposableCowPoller - Just-in-time funding for composable conditional orders.
 contract ComposableCowPoller {
+    using GPv2SafeERC20 for IERC20;
+
     ComposableCoW public immutable composableCow;
 
     /// @notice Parameters for a JIT funding schedule.
@@ -101,7 +104,7 @@ contract ComposableCowPoller {
         if (digest == lastFunded[id]) return;
         lastFunded[id] = digest;
 
-        order.sellToken.transferFrom(schedule.funder, schedule.owner, order.sellAmount);
+        order.sellToken.safeTransferFrom(schedule.funder, schedule.owner, order.sellAmount);
         emit Pulled(id, digest, order.sellAmount);
     }
 }

test/ComposableCowPoller.t.sol

@@ -230,6 +230,28 @@ contract ComposableCowPollerTest is BaseComposableCoWTest {
         assertEq(token0.balanceOf(funder), PART * N - PART, "no extra pull");
     }
 
+    /// @dev A failed ERC-20 transfer must not mark this part as funded.
+    function test_pollFunds_RevertWhen_transferFromReturnsFalse() public {
+        (, bytes32 ctx, bytes32 id) = _setupSchedule();
+        vm.warp(_t0(ctx));
+
+        vm.mockCall(
+            address(token0),
+            abi.encodeWithSelector(
+                token0.transferFrom.selector,
+                funder,
+                address(safe1),
+                PART
+            ),
+            abi.encode(false)
+        );
+
+        vm.expectRevert(bytes("GPv2: failed transferFrom"));
+        poller.pollFunds(id);
+
+        assertEq(poller.lastFunded(id), bytes32(0), "failed pull is not recorded");
+    }
+
     /// @dev The headline flow: each part is funded JIT and the owner holds nothing in between.
     function test_pollFunds_fundsEachPartAcrossSchedule() public {
         (, bytes32 ctx, bytes32 id) = _setupSchedule();