chore: import upstream snapshot with attribution

server/functions/concat.go

@@ -0,0 +1,68 @@
+// Copyright 2026 Dolthub, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package functions
+
+import (
+	"strings"
+
+	"github.com/dolthub/go-mysql-server/sql"
+
+	"github.com/dolthub/doltgresql/server/functions/framework"
+	pgtypes "github.com/dolthub/doltgresql/server/types"
+)
+
+// initConcat registers the functions to the catalog.
+func initConcat() {
+	framework.RegisterFunction(concat_any)
+}
+
+// concat_any represents the PostgreSQL function of the same name, taking the same parameters.
+var concat_any = framework.Function1N{
+	Name:       "concat",
+	Return:     pgtypes.Text,
+	Parameters: [1]*pgtypes.DoltgresType{pgtypes.Any},
+	Strict:     false,
+	Callable: func(ctx *sql.Context, t []*pgtypes.DoltgresType, val1 any, vals []any) (any, error) {
+		sb := strings.Builder{}
+		if val1 != nil {
+			output, err := t[0].IoOutput(ctx, val1)
+			if err != nil {
+				return nil, err
+			}
+			sb.WriteString(output)
+		}
+		for i, val := range vals {
+			if val == nil {
+				continue
+			}
+			valType := t[i+1]
+			if valType.ID == pgtypes.Bool.ID {
+				// Within this context, `bool` returns 't' rather than 'true'
+				if val.(bool) {
+					sb.WriteRune('t')
+				} else {
+					sb.WriteRune('f')
+				}
+			} else {
+				output, err := valType.IoOutput(ctx, val)
+				if err != nil {
+					return nil, err
+				}
+				sb.WriteString(output)
+			}
+		}
+		return sb.String(), nil
+	},
+}