Fix genesis supply handling

proto/cosmos/bank/v1beta1/genesis.proto

@@ -15,7 +15,8 @@ message GenesisState {
   // balances is an array containing the balances of all the accounts.
   repeated Balance balances = 2 [(gogoproto.nullable) = false];
 
-  // supply represents the total supply.
+  // supply represents the total supply. If it is left empty, then supply will be calculated based on the provided
+  // balances. Otherwise, it will be used to validate that the sum of the balances equals this amount.
   repeated cosmos.base.v1beta1.Coin supply = 3
       [(gogoproto.castrepeated) = "github.com/cosmos/cosmos-sdk/types.Coins", (gogoproto.nullable) = false];
 

x/bank/keeper/genesis.go

@@ -11,7 +11,7 @@ import (
 func (k BaseKeeper) InitGenesis(ctx sdk.Context, genState *types.GenesisState) {
 	k.SetParams(ctx, genState.Params)
 
-	var totalSupply sdk.Coins
+	totalSupply := sdk.Coins{}
 
 	genState.Balances = types.SanitizeGenesisBalances(genState.Balances)
 	for _, balance := range genState.Balances {
@@ -27,11 +27,13 @@ func (k BaseKeeper) InitGenesis(ctx sdk.Context, genState *types.GenesisState) {
 		totalSupply = totalSupply.Add(balance.Coins...)
 	}
 
-	if genState.Supply.Empty() {
-		genState.Supply = totalSupply
+	if !genState.Supply.Empty() {
+		if !genState.Supply.IsEqual(totalSupply) {
+			panic(fmt.Errorf("genesis supply is incorrect, expected %v, got %v", genState.Supply, totalSupply))
+		}
 	}
 
-	k.setSupply(ctx, genState.Supply)
+	k.setSupply(ctx, totalSupply)
 
 	for _, meta := range genState.DenomMetadata {
 		k.SetDenomMetaData(ctx, meta)

x/bank/keeper/genesis_test.go

@@ -64,3 +64,50 @@ func (suite *IntegrationTestSuite) TestInitGenesis() {
 	suite.Require().True(found)
 	suite.Require().Equal(m, m2)
 }
+
+func (suite *IntegrationTestSuite) TestTotalSupply() {
+	// Prepare some test data.
+	defaultGenesis := types.DefaultGenesisState()
+	balances := []types.Balance{
+		{Coins: sdk.NewCoins(sdk.NewCoin("foocoin", sdk.NewInt(1))), Address: "cosmos1f9xjhxm0plzrh9cskf4qee4pc2xwp0n0556gh0"},
+		{Coins: sdk.NewCoins(sdk.NewCoin("barcoin", sdk.NewInt(1))), Address: "cosmos1fl48vsnmsdzcv85q5d2q4z5ajdha8yu34mf0eh"},
+		{Coins: sdk.NewCoins(sdk.NewCoin("foocoin", sdk.NewInt(10)), sdk.NewCoin("barcoin", sdk.NewInt(20))), Address: "cosmos1m3h30wlvsf8llruxtpukdvsy0km2kum8g38c8q"},
+	}
+	totalSupply := sdk.NewCoins(sdk.NewCoin("foocoin", sdk.NewInt(11)), sdk.NewCoin("barcoin", sdk.NewInt(21)))
+
+	testcases := []struct {
+		name        string
+		genesis     *types.GenesisState
+		expSupply   sdk.Coins
+		expPanic    bool
+		expPanicMsg string
+	}{
+		{
+			"calculation NOT matching genesis Supply field",
+			types.NewGenesisState(defaultGenesis.Params, balances, sdk.NewCoins(sdk.NewCoin("wrongcoin", sdk.NewInt(1))), defaultGenesis.DenomMetadata),
+			nil, true, "genesis supply is incorrect, expected 1wrongcoin, got 21barcoin,11foocoin",
+		},
+		{
+			"calculation matches genesis Supply field",
+			types.NewGenesisState(defaultGenesis.Params, balances, totalSupply, defaultGenesis.DenomMetadata),
+			totalSupply, false, "",
+		},
+		{
+			"calculation is correct, empty genesis Supply field",
+			types.NewGenesisState(defaultGenesis.Params, balances, nil, defaultGenesis.DenomMetadata),
+			totalSupply, false, "",
+		},
+	}
+
+	for _, tc := range testcases {
+		tc := tc
+		suite.Run(tc.name, func() {
+			if tc.expPanic {
+				suite.PanicsWithError(tc.expPanicMsg, func() { suite.app.BankKeeper.InitGenesis(suite.ctx, tc.genesis) })
+			} else {
+				suite.app.BankKeeper.InitGenesis(suite.ctx, tc.genesis)
+				suite.Require().Equal(tc.expSupply, suite.app.BankKeeper.GetTotalSupply(suite.ctx))
+			}
+		})
+	}
+}

x/bank/types/genesis.go

@@ -18,6 +18,8 @@ func (gs GenesisState) Validate() error {
 	seenBalances := make(map[string]bool)
 	seenMetadatas := make(map[string]bool)
 
+	totalSupply := sdk.Coins{}
+
 	for _, balance := range gs.Balances {
 		if seenBalances[balance.Address] {
 			return fmt.Errorf("duplicate balance for address %s", balance.Address)
@@ -28,6 +30,8 @@ func (gs GenesisState) Validate() error {
 		}
 
 		seenBalances[balance.Address] = true
+
+		totalSupply = totalSupply.Add(balance.Coins...)
 	}
 
 	for _, metadata := range gs.DenomMetadata {
@@ -42,8 +46,19 @@ func (gs GenesisState) Validate() error {
 		seenMetadatas[metadata.Base] = true
 	}
 
-	// NOTE: this errors if supply for any given coin is zero
-	return gs.Supply.Validate()
+	if !gs.Supply.Empty() {
+		// NOTE: this errors if supply for any given coin is zero
+		err := gs.Supply.Validate()
+		if err != nil {
+			return err
+		}
+
+		if !gs.Supply.IsEqual(totalSupply) {
+			return fmt.Errorf("genesis supply is incorrect, expected %v, got %v", gs.Supply, totalSupply)
+		}
+	}
+
+	return nil
 }
 
 // NewGenesisState creates a new genesis state.