fix: Revert reserves cap change due breaking change at ILendingPool interface with current deployed markets

Author: kartojal

contracts/protocol/lendingpool/LendingPool.sol

@@ -87,7 +87,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
     _addressesProvider = provider;
     _maxStableRateBorrowSizePercent = 2500;
     _flashLoanPremiumTotal = 9;
-    _maxNumberOfReserves = UserConfiguration._maxReserves;
+    _maxNumberOfReserves = 128;
   }
 
   /**
@@ -713,7 +713,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
   }
 
   /**
-   * @dev Returns the fee on flash loans
+   * @dev Returns the fee on flash loans 
    */
   function FLASHLOAN_PREMIUM_TOTAL() public view returns (uint256) {
     return _flashLoanPremiumTotal;

contracts/protocol/libraries/configuration/UserConfiguration.sol

@@ -13,9 +13,6 @@ library UserConfiguration {
   uint256 internal constant BORROWING_MASK =
     0x5555555555555555555555555555555555555555555555555555555555555555;
 
-  uint256 internal constant _maxReserves = 256;
-  uint256 internal constant _indexCount = _maxReserves / 128 + ((_maxReserves % 128 > 0) ? 1 : 0);
-
   /**
    * @dev Sets if the user is borrowing the reserve identified by reserveIndex
    * @param self The configuration object
@@ -27,11 +24,9 @@ library UserConfiguration {
     uint256 reserveIndex,
     bool borrowing
   ) internal {
-    require(reserveIndex < _maxReserves, Errors.UL_INVALID_INDEX);
-    uint256 index = reserveIndex / 128;
-    reserveIndex = reserveIndex % 128;
-    self.data[index] =
-      (self.data[index] & ~(1 << (reserveIndex * 2))) |
+    require(reserveIndex < 128, Errors.UL_INVALID_INDEX);
+    self.data =
+      (self.data & ~(1 << (reserveIndex * 2))) |
       (uint256(borrowing ? 1 : 0) << (reserveIndex * 2));
   }
 
@@ -46,11 +41,9 @@ library UserConfiguration {
     uint256 reserveIndex,
     bool usingAsCollateral
   ) internal {
-    require(reserveIndex < _maxReserves, Errors.UL_INVALID_INDEX);
-    uint256 index = reserveIndex / 128;
-    reserveIndex = reserveIndex % 128;
-    self.data[index] =
-      (self.data[index] & ~(1 << (reserveIndex * 2 + 1))) |
+    require(reserveIndex < 128, Errors.UL_INVALID_INDEX);
+    self.data =
+      (self.data & ~(1 << (reserveIndex * 2 + 1))) |
       (uint256(usingAsCollateral ? 1 : 0) << (reserveIndex * 2 + 1));
   }
 
@@ -64,10 +57,8 @@ library UserConfiguration {
     DataTypes.UserConfigurationMap memory self,
     uint256 reserveIndex
   ) internal pure returns (bool) {
-    require(reserveIndex < _maxReserves, Errors.UL_INVALID_INDEX);
-    uint256 index = reserveIndex / 128;
-    reserveIndex = reserveIndex % 128;
-    return (self.data[index] >> (reserveIndex * 2)) & 3 != 0;
+    require(reserveIndex < 128, Errors.UL_INVALID_INDEX);
+    return (self.data >> (reserveIndex * 2)) & 3 != 0;
   }
 
   /**
@@ -81,10 +72,8 @@ library UserConfiguration {
     pure
     returns (bool)
   {
-    require(reserveIndex < _maxReserves, Errors.UL_INVALID_INDEX);
-    uint256 index = reserveIndex / 128;
-    reserveIndex = reserveIndex % 128;
-    return (self.data[index] >> (reserveIndex * 2)) & 1 != 0;
+    require(reserveIndex < 128, Errors.UL_INVALID_INDEX);
+    return (self.data >> (reserveIndex * 2)) & 1 != 0;
   }
 
   /**
@@ -98,10 +87,8 @@ library UserConfiguration {
     pure
     returns (bool)
   {
-    require(reserveIndex < _maxReserves, Errors.UL_INVALID_INDEX);
-    uint256 index = reserveIndex / 128;
-    reserveIndex = reserveIndex % 128;
-    return (self.data[index] >> (reserveIndex * 2 + 1)) & 1 != 0;
+    require(reserveIndex < 128, Errors.UL_INVALID_INDEX);
+    return (self.data >> (reserveIndex * 2 + 1)) & 1 != 0;
   }
 
   /**
@@ -110,12 +97,7 @@ library UserConfiguration {
    * @return True if the user has been borrowing any reserve, false otherwise
    **/
   function isBorrowingAny(DataTypes.UserConfigurationMap memory self) internal pure returns (bool) {
-    for (uint8 i = 0; i < _indexCount; i++) {
-      if (self.data[i] & BORROWING_MASK != 0) {
-        return true;
-      }
-    }
-    return false;
+    return self.data & BORROWING_MASK != 0;
   }
 
   /**
@@ -124,11 +106,6 @@ library UserConfiguration {
    * @return True if the user has been borrowing any reserve, false otherwise
    **/
   function isEmpty(DataTypes.UserConfigurationMap memory self) internal pure returns (bool) {
-    for (uint8 i = 0; i < _indexCount; i++) {
-      if (self.data[i] != 0) {
-        return false;
-      }
-    }
-    return true;
+    return self.data == 0;
   }
 }

contracts/protocol/libraries/types/DataTypes.sol

@@ -42,7 +42,7 @@ library DataTypes {
   }
 
   struct UserConfigurationMap {
-    uint256[2] data; // size is _maxReserves / 128 + ((_maxReserves % 128 > 0) ? 1 : 0), but need to be literal
+    uint256 data;
   }
 
   enum InterestRateMode {NONE, STABLE, VARIABLE}