From 4521be2363492d94728a3720333fe11a0ebffd0a Mon Sep 17 00:00:00 2001
From: kinrezc <matt.czernik@gmail.com>
Date: Mon, 15 Jul 2024 14:53:16 -0400
Subject: [PATCH] fix: eth -> yt swap

---
 src/RMM.sol                         | 18 ++++++++----------
 test/invariant/RMMHandler.sol       |  2 +-
 test/unit/SwapExactTokenForYt.t.sol |  2 +-
 3 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/src/RMM.sol b/src/RMM.sol
index 83012f5..43f4a51 100644
--- a/src/RMM.sol
+++ b/src/RMM.sol
@@ -180,7 +180,7 @@ contract RMM is ERC20 {
         uint256 upperBound,
         uint256 epsilon,
         address to
-    ) external payable lock returns (uint256 amountInWad, uint256 amountOutWad, int256 deltaLiquidity) {
+    ) external payable lock returns (uint256 ytOut, uint256 amountInWad, uint256 amountOutWad, int256 deltaLiquidity) {
         SwapToYt memory swap;
         swap.tokenIn = token;
         swap.amountTokenIn = token == address(0) ? 0 : amountTokenIn;
@@ -193,27 +193,25 @@ contract RMM is ERC20 {
 
         PYIndex index = YT.newIndex();
         uint256 strike_;
-        uint256 amountOut;
 
         swap.amountPtIn = computeSYToYT(index, swap.realSyMinted, upperBound, block.timestamp, swap.amountPtIn, epsilon);
 
-        (amountInWad, amountOutWad, amountOut, deltaLiquidity, strike_) =
+        (amountInWad, amountOutWad, ytOut, deltaLiquidity, strike_) =
             prepareSwapPtIn(swap.amountPtIn, block.timestamp, index);
 
         _adjust(-toInt(amountOutWad), toInt(amountInWad), deltaLiquidity, strike_, index);
 
         // SY is needed to cover the minted PT, so we need to debit the delta from the msg.sender
-        swap.realYtOut = amountOut + (index.assetToSyUp(amountInWad) - amountOutWad);
+        ytOut += (index.assetToSyUp(amountInWad) - amountOutWad);
 
         // Converts the SY received from minting it into its components PT and YT.
-        amountOut = mintPtYt(swap.realYtOut, address(this));
-        swap.realYtOut = amountOut;
+        ytOut = mintPtYt(ytOut, address(this));
 
-        if (swap.realYtOut < swap.minYtOut) {
-            revert InsufficientOutput(amountInWad, swap.minYtOut, swap.realYtOut);
+        if (ytOut < swap.minYtOut) {
+            revert InsufficientOutput(amountInWad, swap.minYtOut, ytOut);
         }
 
-        _credit(address(YT), to, swap.realYtOut);
+        _credit(address(YT), to, ytOut);
 
         uint256 debitSurplus = address(this).balance;
         if (debitSurplus > 0) {
@@ -226,7 +224,7 @@ contract RMM is ERC20 {
             address(SY),
             address(YT),
             swap.amountTokenIn + swap.amountNativeIn - debitSurplus,
-            swap.realYtOut,
+            ytOut,
             deltaLiquidity
         );
     }
diff --git a/test/invariant/RMMHandler.sol b/test/invariant/RMMHandler.sol
index ceed198..f0d828c 100644
--- a/test/invariant/RMMHandler.sol
+++ b/test/invariant/RMMHandler.sol
@@ -167,7 +167,7 @@ contract RMMHandler is CommonBase, StdUtils, StdCheats {
         );
 
         weth.approve(address(rmm), amountTokenIn);
-        (uint256 amountInWad, uint256 amountOutWad, int256 deltaLiquidity) = rmm.swapExactTokenForYt(
+        (uint256 realYtOut, uint256 amountInWad, uint256 amountOutWad, int256 deltaLiquidity) = rmm.swapExactTokenForYt(
             address(weth),
             amountTokenIn,
             ytOut,
diff --git a/test/unit/SwapExactTokenForYt.t.sol b/test/unit/SwapExactTokenForYt.t.sol
index ee7a4d3..10c0661 100644
--- a/test/unit/SwapExactTokenForYt.t.sol
+++ b/test/unit/SwapExactTokenForYt.t.sol
@@ -27,7 +27,7 @@ contract SwapExactTokenForYtTest is SetUp {
         PYIndex index = YT.newIndex();
         (uint256 syMinted, uint256 ytOut) =
             rmm.computeTokenToYT(index, address(0), amountIn, 0, block.timestamp, 0, 1_000);
-        (, uint256 amountOut,) = rmm.swapExactTokenForYt{value: amountIn}(
+        (uint256 amountOut,,,) = rmm.swapExactTokenForYt{value: amountIn}(
             address(0), amountIn, ytOut, syMinted, ytOut, 0, 0.005 ether, address(this)
         );