lang: Move type duplicates checker into a separate package

lang/funcs/simplepoly/simplepoly.go

@@ -23,6 +23,7 @@ import (
 	"github.com/purpleidea/mgmt/lang/funcs"
 	"github.com/purpleidea/mgmt/lang/interfaces"
 	"github.com/purpleidea/mgmt/lang/types"
+	langutil "github.com/purpleidea/mgmt/lang/util"
 	"github.com/purpleidea/mgmt/util/errwrap"
 )
 
@@ -55,7 +56,7 @@ func Register(name string, fns []*types.FuncValue) {
 		typs = append(typs, f.T)
 	}
 
-	if err := hasDuplicateTypes(typs); err != nil {
+	if err := langutil.HasDuplicateTypes(typs); err != nil {
 		panic(fmt.Sprintf("polyfunc %s has a duplicate implementation: %+v", name, err))
 	}
 
@@ -179,7 +180,7 @@ func (obj *simplePolyFunc) Validate() error {
 		typs = append(typs, f.T)
 	}
 
-	if err := hasDuplicateTypes(typs); err != nil {
+	if err := langutil.HasDuplicateTypes(typs); err != nil {
 		return errwrap.Wrapf(err, "duplicate implementation found")
 	}
 
@@ -278,19 +279,3 @@ func (obj *simplePolyFunc) Close() error {
 	close(obj.closeChan)
 	return nil
 }
-
-// hasDuplicateTypes returns an error if the list of types is not unique.
-func hasDuplicateTypes(typs []*types.Type) error {
-	// FIXME: do this comparison in < O(n^2) ?
-	for i, ti := range typs {
-		for j, tj := range typs {
-			if i == j {
-				continue // don't compare to self
-			}
-			if ti.Cmp(tj) == nil {
-				return fmt.Errorf("duplicate type of %+v found", ti)
-			}
-		}
-	}
-	return nil
-}

lang/util/util.go

@@ -0,0 +1,40 @@
+// Mgmt
+// Copyright (C) 2013-2019+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package util
+
+import (
+	"fmt"
+
+	"github.com/purpleidea/mgmt/lang/types"
+)
+
+// HasDuplicateTypes returns an error if the list of types is not unique.
+func HasDuplicateTypes(typs []*types.Type) error {
+	// FIXME: do this comparison in < O(n^2) ?
+	for i, ti := range typs {
+		for j, tj := range typs {
+			if i == j {
+				continue // don't compare to self
+			}
+			if ti.Cmp(tj) == nil {
+				return fmt.Errorf("duplicate type of %+v found", ti)
+			}
+		}
+	}
+	return nil
+}

test/test-govet.sh

@@ -62,6 +62,10 @@ function consistent-imports() {
 	if grep $'\t"github.com/hashicorp/go-multierror"' "$1"; then
 		return 1
 	fi
+	# import as langutil
+	if grep $'\t"github.com/purpleidea/mgmt/lang/util"' "$1"; then
+		return 1
+	fi
 	if grep $'\t"github.com/purpleidea/mgmt/engine/util"' "$1"; then	# import as engineUtil
 		return 1
 	fi