From 666d47dc71da626d0a1be0a62427561503978205 Mon Sep 17 00:00:00 2001
From: Rohan Yadav <rohany@alumni.cmu.edu>
Date: Mon, 31 Aug 2020 16:11:12 -0400
Subject: [PATCH] sql: update `format_type` to handle user defined types

Fixes #53684.

Update the `format_type` builtin to handle user defined types.

Release justification: bug fix
Release note: None
---
 pkg/sql/faketreeeval/evalctx.go               | 13 +++++++++++
 .../logictest/testdata/logic_test/pg_builtins | 15 ++++++++++++
 pkg/sql/sem/builtins/pg_builtins.go           | 23 ++++++++++++++++---
 pkg/sql/sem/tree/eval.go                      |  1 +
 4 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/pkg/sql/faketreeeval/evalctx.go b/pkg/sql/faketreeeval/evalctx.go
index 5b7eebdb800d..58db1900119f 100644
--- a/pkg/sql/faketreeeval/evalctx.go
+++ b/pkg/sql/faketreeeval/evalctx.go
@@ -22,6 +22,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/types"
 	"github.com/cockroachdb/cockroach/pkg/util/errorutil/unimplemented"
 	"github.com/cockroachdb/errors"
+	"github.com/lib/pq/oid"
 )
 
 // DummySequenceOperators implements the tree.SequenceOperators interface by
@@ -119,6 +120,18 @@ func (ep *DummyEvalPlanner) EvalSubquery(expr *tree.Subquery) (tree.Datum, error
 	return nil, errors.WithStack(errEvalPlanner)
 }
 
+// ResolveTypeByOID implements the tree.TypeReferenceResolver interface.
+func (ep *DummyEvalPlanner) ResolveTypeByOID(_ context.Context, _ oid.Oid) (*types.T, error) {
+	return nil, errors.WithStack(errEvalPlanner)
+}
+
+// ResolveType implements the tree.TypeReferenceResolver interface.
+func (ep *DummyEvalPlanner) ResolveType(
+	_ context.Context, _ *tree.UnresolvedObjectName,
+) (*types.T, error) {
+	return nil, errors.WithStack(errEvalPlanner)
+}
+
 // DummyPrivilegedAccessor implements the tree.PrivilegedAccessor interface by returning errors.
 type DummyPrivilegedAccessor struct{}
 
diff --git a/pkg/sql/logictest/testdata/logic_test/pg_builtins b/pkg/sql/logictest/testdata/logic_test/pg_builtins
index e2f4b966e1f0..f441ff9cdfe7 100644
--- a/pkg/sql/logictest/testdata/logic_test/pg_builtins
+++ b/pkg/sql/logictest/testdata/logic_test/pg_builtins
@@ -18,3 +18,18 @@ SELECT pg_my_temp_schema()
 # Regression test for #49072.
 statement ok
 SELECT has_table_privilege('root'::NAME, 0, 'select')
+
+# Regression test for #53684.
+statement ok
+CREATE TYPE typ AS ENUM ('hello')
+
+query T
+SELECT format_type(oid, 0) FROM pg_catalog.pg_type WHERE typname = 'typ'
+----
+typ
+
+# Nothing breaks if we put a non-existing oid into format_type.
+query T
+SELECT format_type(152100, 0)
+----
+unknown (OID=152100)
diff --git a/pkg/sql/sem/builtins/pg_builtins.go b/pkg/sql/sem/builtins/pg_builtins.go
index 5b45d38ef68c..7d00d9e31a57 100644
--- a/pkg/sql/sem/builtins/pg_builtins.go
+++ b/pkg/sql/sem/builtins/pg_builtins.go
@@ -16,6 +16,7 @@ import (
 	"time"
 
 	"github.com/cockroachdb/cockroach/pkg/keys"
+	"github.com/cockroachdb/cockroach/pkg/sql/catalog"
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/catconstants"
 	"github.com/cockroachdb/cockroach/pkg/sql/parser"
 	"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgcode"
@@ -827,7 +828,7 @@ var pgBuiltins = map[string]builtinDefinition{
 		},
 	),
 
-	"format_type": makeBuiltin(tree.FunctionProperties{NullableArgs: true},
+	"format_type": makeBuiltin(tree.FunctionProperties{NullableArgs: true, DistsqlBlocklist: true},
 		tree.Overload{
 			Types:      tree.ArgTypes{{"type_oid", types.Oid}, {"typemod", types.Int}},
 			ReturnType: tree.FixedReturnType(types.String),
@@ -838,9 +839,25 @@ var pgBuiltins = map[string]builtinDefinition{
 					return tree.DNull, nil
 				}
 				maybeTypmod := args[1]
-				typ, ok := types.OidToType[oid.Oid(int(oidArg.(*tree.DOid).DInt))]
+				oid := oid.Oid(int(oidArg.(*tree.DOid).DInt))
+				typ, ok := types.OidToType[oid]
 				if !ok {
-					return tree.NewDString(fmt.Sprintf("unknown (OID=%s)", oidArg)), nil
+					// If the type wasn't statically known, try looking it up as a user
+					// defined type.
+					var err error
+					typ, err = ctx.Planner.ResolveTypeByOID(ctx.Context, oid)
+					if err != nil {
+						// If the error is a descriptor does not exist error, then swallow it.
+						unknown := tree.NewDString(fmt.Sprintf("unknown (OID=%s)", oidArg))
+						switch {
+						case errors.Is(err, catalog.ErrDescriptorNotFound):
+							return unknown, nil
+						case pgerror.GetPGCode(err) == pgcode.UndefinedObject:
+							return unknown, nil
+						default:
+							return nil, err
+						}
+					}
 				}
 				var hasTypmod bool
 				var typmod int
diff --git a/pkg/sql/sem/tree/eval.go b/pkg/sql/sem/tree/eval.go
index 479ba7d14234..7d1531d210f8 100644
--- a/pkg/sql/sem/tree/eval.go
+++ b/pkg/sql/sem/tree/eval.go
@@ -2993,6 +2993,7 @@ type EvalDatabase interface {
 // EvalPlanner is a limited planner that can be used from EvalContext.
 type EvalPlanner interface {
 	EvalDatabase
+	TypeReferenceResolver
 	// ParseType parses a column type.
 	ParseType(sql string) (*types.T, error)