Improve linter setup (#185)

* [linter] Remove unused exclusions

Linter `nosnakecase` was removed in 1e1138d0268a9896a1bd058e9b65b808eb20666e.

* [linter] Add tool for code clone detection

* [linter] Add `errorlint`

Find code that will cause problems with the error wrapping scheme
introduced in Go 1.13.

* [linter] Add `exhaustive`

Check exhaustiveness of enum switch statements.

* [linter] Add `forcetypeassert`

Finds type assertions which did forcely such as below:
```
func f() {
	var a interface{}
	_ = a.(int) // type assertion must be checked
}
```

* [linter] Add `gocritic`

Provides diagnostics that check for bugs, performance and style issues.

Signed-off-by: Julian Strobl <jmastr@mailbox.org>

.golangci.yaml

@@ -11,19 +11,24 @@ linters:
     - contextcheck
     - decorder
     - dogsled
+    - dupl
     - dupword
     - durationcheck
     - errcheck
     - errchkjson
     - errname
+    - errorlint
     - execinquery
+    - exhaustive
     - exportloopref
     - forbidigo
+    - forcetypeassert
     - ginkgolinter
     - gocheckcompilerdirectives
     - gochecksumtype
     - gocognit
     - goconst
+    - gocritic
     - gocyclo
     - gofmt
     - goheader
@@ -71,12 +76,12 @@ linters-settings:
     max-func-lines: 100
 issues:
   exclude-rules:
-    - path: codec\.go
+    - path: x/.*/types/message.*\.go
       linters:
-        - nosnakecase
-    - path: app\/simulation_test\.go
+        - dupl
+    - path: x/dao/client/cli/tx_reissue_rddl.*\.go
       linters:
-        - nosnakecase
-    - path: testutil\/rest\.go
+        - dupl
+    - path: testutil/nullify/nullify\.go
       linters:
-        - nosnakecase
+        - exhaustive

cmd/planetmint-god/cmd/root.go

@@ -112,7 +112,10 @@ func initRootCmd(
 	// Set config
 	initSDKConfig()
 
-	gentxModule := app.ModuleBasics[genutiltypes.ModuleName].(genutil.AppModuleBasic)
+	gentxModule, ok := app.ModuleBasics[genutiltypes.ModuleName].(genutil.AppModuleBasic)
+	if !ok {
+		panic("forced type assertion failed for gentxModule")
+	}
 	rootCmd.AddCommand(
 		genutilcli.InitCmd(app.ModuleBasics, app.DefaultNodeHome),
 		genutilcli.CollectGenTxsCmd(banktypes.GenesisBalancesIterator{}, app.DefaultNodeHome, gentxModule.GenTxValidator),

cmd/planetmint-god/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"os"
 
 	"github.com/cosmos/cosmos-sdk/server"
@@ -13,12 +14,10 @@ import (
 func main() {
 	rootCmd, _ := cmd.NewRootCmd()
 	if err := svrcmd.Execute(rootCmd, "", app.DefaultNodeHome); err != nil {
-		switch e := err.(type) {
-		case server.ErrorCode:
+		var e *server.ErrorCode
+		if errors.As(err, &e) {
 			os.Exit(e.Code)
-
-		default:
+		}
 		os.Exit(1)
 	}
 }
-}

x/dao/keeper/distribution.go

@@ -65,10 +65,10 @@ func getLastPopBytes(height int64) []byte {
 	return big.NewInt(height + 1).Bytes()
 }
 
-func ComputeDistribution(lastReissuance int64, BlockHeight int64, amount uint64) (distribution types.DistributionOrder) {
+func ComputeDistribution(lastReissuance int64, blockHeight int64, amount uint64) (distribution types.DistributionOrder) {
 	conf := config.GetConfig()
 	distribution.FirstPop = lastReissuance
-	distribution.LastPop = BlockHeight
+	distribution.LastPop = blockHeight
 
 	distribution.DaoAddr = conf.DistributionAddrDAO
 	distribution.InvestorAddr = conf.DistributionAddrInv
@@ -109,7 +109,7 @@ func (k Keeper) GetDistributionForReissuedTokens(ctx sdk.Context, blockHeight in
 			(lastPoP < obj.BlockHeight && obj.BlockHeight <= blockHeight) {
 			amount, err := getUint64FromTxString(ctx, obj.Rawtx)
 			if err == nil {
-				overallAmount = overallAmount + amount
+				overallAmount += amount
 			}
 		} else {
 			ctx.Logger().Info("%u %u %u", lastPoP, obj.BlockHeight, blockHeight)