chore: import upstream snapshot with attribution

server/ast/no_op.go

@@ -0,0 +1,57 @@
+// Copyright 2025 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 ast
+
+import (
+	"os"
+
+	"github.com/cockroachdb/errors"
+	vitess "github.com/dolthub/vitess/go/vt/sqlparser"
+
+	pgnodes "github.com/dolthub/doltgresql/server/node"
+)
+
+const ignoreUnsupportedEnvKey = "DOLTGRES_IGNORE_UNSUPPORTED"
+
+// ignoreUnsupportedStatements is a flag that determines whether to ignore unsupported statements. This is useful
+// when importing a dump from postgres using certain import tools that expect every statement to succeed, including
+// ones that we can't yet fully support (or that we never will, but are safe to ignore).
+var ignoreUnsupportedStatements bool
+
+func init() {
+	if _, ignoreUnsupported := os.LookupEnv(ignoreUnsupportedEnvKey); ignoreUnsupported {
+		ignoreUnsupportedStatements = true
+	}
+}
+
+// NewNoOp returns a new NoOp statement which does nothing and issues zero or more warnings when run.
+// Used for statements that aren't directly supported but which we don't want to cause errors.
+func NewNoOp(warnings ...string) vitess.InjectedStatement {
+	return vitess.InjectedStatement{
+		Statement: pgnodes.NoOp{
+			Warnings: warnings,
+		},
+	}
+}
+
+// NotYetSupportedError returns an unsupported error with the given message, or a NoOp statement if the environment
+// variable DOLTGRES_IGNORE_UNSUPPORTED is set.
+func NotYetSupportedError(errorMsg string) (vitess.Statement, error) {
+	if ignoreUnsupportedStatements {
+		return NewNoOp(errorMsg), nil
+	}
+
+	return nil, errors.Errorf(errorMsg + " Please file an issue at https://github.com/dolthub/doltgresql/issues")
+}