Merge pull request #132455 from cockroachdb/blathers/backport-release…

…-24.2-132348

release-24.2: sql: fix panic caused by type resolution in AOST expression

pkg/sql/logictest/testdata/logic_test/txn_as_of

@@ -280,3 +280,15 @@ SET TRANSACTION AS OF SYSTEM TIME '0'
 
 statement ok
 ROLLBACK
+
+statement error AS OF SYSTEM TIME: only constant expressions or follower_read_timestamp are allowed
+BEGIN TRANSACTION AS OF SYSTEM TIME ('abc' IS OF (ident))
+
+statement ok
+BEGIN
+
+statement error AS OF SYSTEM TIME: only constant expressions or follower_read_timestamp are allowed
+SET TRANSACTION AS OF SYSTEM TIME ('abc' IS OF (ident))
+
+statement ok
+ROLLBACK

pkg/sql/schema_resolver.go

@@ -122,7 +122,6 @@ func (sr *schemaResolver) byNameGetterBuilder() descs.ByNameGetterBuilder {
 func (sr *schemaResolver) LookupObject(
 	ctx context.Context, flags tree.ObjectLookupFlags, dbName, scName, obName string,
 ) (found bool, prefix catalog.ResolvedObjectPrefix, desc catalog.Descriptor, err error) {
-
 	// Check if we are looking up a type which matches a built-in type in
 	// CockroachDB but is an extension type on the public schema in PostgreSQL.
 	if flags.DesiredObjectKind == tree.TypeObject && scName == catconstants.PublicSchemaName {

pkg/sql/sem/asof/BUILD.bazel

@@ -19,6 +19,7 @@ go_library(
         "//pkg/util/hlc",
         "@com_github_cockroachdb_apd_v3//:apd",
         "@com_github_cockroachdb_errors//:errors",
+        "@com_github_lib_pq//oid",
     ],
 )
 

pkg/sql/sem/asof/as_of.go

@@ -20,6 +20,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/util/duration"
 	"github.com/cockroachdb/cockroach/pkg/util/hlc"
 	"github.com/cockroachdb/errors"
+	"github.com/lib/pq/oid"
 )
 
 // FollowerReadTimestampFunctionName is the name of the function which can be
@@ -132,6 +133,14 @@ func Eval(
 	defer scalarProps.Restore(*scalarProps)
 	scalarProps.Require("AS OF SYSTEM TIME", tree.RejectSpecial|tree.RejectSubqueries)
 
+	// Disable type resolution. Since type resolution requires a transaction, but
+	// this expression is being evaluated before a transaction begins, resolving
+	// any type should result in an error. There is no valid AS OF SYSTEM TIME
+	// expression that requires type resolution.
+	origTypeResolver := semaCtx.GetTypeResolver()
+	semaCtx.TypeResolver = &asOfTypeResolver{errFactory: newInvalidExprError}
+	defer func() { semaCtx.TypeResolver = origTypeResolver }()
+
 	var ret eval.AsOfSystemTime
 
 	// In order to support the follower reads feature we permit this expression
@@ -204,6 +213,29 @@ func Eval(
 	return ret, nil
 }
 
+// asOfTypeResolver is a type resolver that always returns an error. It is used
+// to block type resolution while evaluating the AS OF SYSTEM TIME expression.
+type asOfTypeResolver struct {
+	// errFactory is a function that returns the error to be returned by the
+	// type resolver. Using a closure lets us avoid instantiating the error
+	// unless something actually tries to resolve a type.
+	errFactory func() error
+}
+
+var _ tree.TypeReferenceResolver = (*asOfTypeResolver)(nil)
+
+// ResolveType implements the tree.TypeReferenceResolver interface.
+func (r *asOfTypeResolver) ResolveType(
+	ctx context.Context, name *tree.UnresolvedObjectName,
+) (*types.T, error) {
+	return nil, r.errFactory()
+}
+
+// ResolveTypeByOID implements the tree.TypeReferenceResolver interface.
+func (r *asOfTypeResolver) ResolveTypeByOID(ctx context.Context, oid oid.Oid) (*types.T, error) {
+	return nil, r.errFactory()
+}
+
 // DatumToHLCUsage specifies which statement DatumToHLC() is used for.
 type DatumToHLCUsage int64