feat(x/mint): Add max supply param

tests/e2e/mint/grpc.go

@@ -29,7 +29,7 @@ func (s *E2ETestSuite) TestQueryGRPC() {
 			&minttypes.QueryParamsResponse{},
 			&minttypes.QueryParamsResponse{
 				Params: minttypes.NewParams("stake", math.LegacyNewDecWithPrec(13, 2), math.LegacyNewDecWithPrec(100, 2),
-					math.LegacyNewDec(1), math.LegacyNewDecWithPrec(67, 2), (60 * 60 * 8766 / 5)),
+					math.LegacyNewDec(1), math.LegacyNewDecWithPrec(67, 2), (60 * 60 * 8766 / 5), math.ZeroInt()),
 			},
 		},
 		{

x/mint/CHANGELOG.md

@@ -27,6 +27,8 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Features
 
+* [19896](https://github.com/cosmos/cosmos-sdk/pull/19896) Added a new max supply genesis param to existing params.
+
 ### Improvements
 
 ### API Breaking Changes

x/mint/README.md

@@ -137,14 +137,15 @@ BlockProvision(params Params) sdk.Coin {
 
 The minting module contains the following parameters:
 
-| Key                 | Type            | Example                |
-|---------------------|-----------------|------------------------|
-| MintDenom           | string          | "uatom"                |
-| InflationRateChange | string (dec)    | "0.130000000000000000" |
-| InflationMax        | string (dec)    | "0.200000000000000000" |
-| InflationMin        | string (dec)    | "0.070000000000000000" |
-| GoalBonded          | string (dec)    | "0.670000000000000000" |
-| BlocksPerYear       | string (uint64) | "6311520"              |
+| Key                 | Type             | Example                |
+|---------------------|------------------|------------------------|
+| MintDenom           | string           | "uatom"                |
+| InflationRateChange | string (dec)     | "0.130000000000000000" |
+| InflationMax        | string (dec)     | "0.200000000000000000" |
+| InflationMin        | string (dec)     | "0.070000000000000000" |
+| GoalBonded          | string (dec)     | "0.670000000000000000" |
+| BlocksPerYear       | string (uint64)  | "6311520"              |
+| MaxSupply           | string (math.Int)| "0"                    |
 
 
 ## Events
@@ -306,7 +307,8 @@ Example Output:
     "inflationMax": "200000000000000000",
     "inflationMin": "70000000000000000",
     "goalBonded": "670000000000000000",
-    "blocksPerYear": "6311520"
+    "blocksPerYear": "6311520",
+    "maxSupply": "0",
   }
 }
 ```
@@ -377,7 +379,8 @@ Example Output:
     "inflationMax": "200000000000000000",
     "inflationMin": "70000000000000000",
     "goalBonded": "670000000000000000",
-    "blocksPerYear": "6311520"
+    "blocksPerYear": "6311520",
+    "maxSupply": "0",
   }
 }
 ```

x/mint/keeper/abci.go

@@ -37,19 +37,43 @@
 		return err
 	}
 
+	// update minter's inflation and annual provisions
 	minter.Inflation = ic(ctx, minter, params, bondedRatio)
 	minter.AnnualProvisions = minter.NextAnnualProvisions(params, totalStakingSupply)
 	if err = k.Minter.Set(ctx, minter); err != nil {
 		return err
 	}
 
-	// mint coins, update supply
+	// calculate minted coins
 	mintedCoin := minter.BlockProvision(params)
 	mintedCoins := sdk.NewCoins(mintedCoin)
 
-	err = k.MintCoins(ctx, mintedCoins)
-	if err != nil {
-		return err
+	maxSupply := params.MaxSupply
+	totalSupply := k.bankKeeper.GetSupply(ctx, params.MintDenom).Amount // fetch total supply from the bank module
+
+	// if maxSupply is not infinite, check against max_supply parameter
+	if !maxSupply.IsZero() {
+		if totalSupply.Add(mintedCoins.AmountOf(params.MintDenom)).GT(maxSupply) {
+			// calculate the difference between maxSupply and totalSupply
+			diff := maxSupply.Sub(totalSupply)
+			// mint the difference
+			diffCoin := sdk.NewCoin(params.MintDenom, diff)
+			diffCoins := sdk.NewCoins(diffCoin)
+
+			// mint coins
+			if err := k.MintCoins(ctx, diffCoins); err != nil {
+				return err
+			}
+			mintedCoins = diffCoins
+		}
+	}
+
+	// mint coins if maxSupply is infinite or total staking supply is less than maxSupply
+	if maxSupply.IsZero() || totalSupply.Add(mintedCoins.AmountOf(params.MintDenom)).LT(maxSupply) {
+		// mint coins
+		if err := k.MintCoins(ctx, mintedCoins); err != nil {
+			return err
+		}
 	}
 
 	// send the minted coins to the fee collector account

x/mint/keeper/genesis_test.go

@@ -71,6 +71,7 @@ func (s *GenesisTestSuite) TestImportExportGenesis() {
 		math.LegacyNewDecWithPrec(9, 2),
 		math.LegacyNewDecWithPrec(69, 2),
 		uint64(60*60*8766/5),
+		math.ZeroInt(),
 	)
 
 	err := s.keeper.InitGenesis(s.sdkCtx, s.accountKeeper, genesisState)

x/mint/keeper/migrator.go

@@ -1,6 +1,10 @@
 package keeper
 
-import "context"
+import (
+	"context"
+
+	"cosmossdk.io/math"
+)
 
 // Migrator is a struct for handling in-place state migrations.
 type Migrator struct {
@@ -21,3 +25,23 @@ func NewMigrator(k Keeper) Migrator {
 func (m Migrator) Migrate1to2(ctx context.Context) error {
 	return nil
 }
+
+// Migrate2to3 migrates the x/mint module state from the consensus version 2 to
+// version 3.
+func (m Migrator) Migrate2to3(ctx context.Context) error {
+	params, err := m.keeper.Params.Get(ctx)
+	if err != nil {
+		return err
+	}
+
+	// Initialize the new MaxSupply parameter with the default value
+	params.MaxSupply = math.ZeroInt()
+
+	// Set the updated params
+	err = m.keeper.Params.Set(ctx, params)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}

x/mint/keeper/msg_server_test.go

@@ -53,6 +53,7 @@ func (s *IntegrationTestSuite) TestUpdateParams() {
 					InflationMin:        sdkmath.LegacyNewDecWithPrec(2, 2),
 					GoalBonded:          sdkmath.LegacyNewDecWithPrec(37, 2),
 					BlocksPerYear:       uint64(60 * 60 * 8766 / 5),
+					MaxSupply:           sdkmath.ZeroInt(), // infinite supply
 				},
 			},
 			expectErr: false,