sql: code to check whether a sequence exists is bad

[ajwerner]

Describe the problem

The code to check whether a sequence exists uses descriptor resolution APIs which indicate a name is not in use when it's in use by a type.

cockroach/pkg/sql/serial.go

Lines 94 to 97 in 3e4a440

	res, err := p.resolveUncachedTableDescriptor(ctx, seqName, false /*required*/, tree.ResolveAnyTableKind)
	if err != nil {
	return nil, nil, nil, nil, err
	}

To Reproduce

set serial_normalization = 'sql_sequence';
create type t_t_seq AS enum ('a');
create table t (t SERIAL PRIMARY KEY);

Leads to this inscrutible error:

ERROR: unexpected value: raw_bytes:"\304\244\321\003\001v" timestamp:<wall_time:1637082444028995000 > 

Expected behavior
We call the sequence t_t_seq1

Additional context
The deeper problem here is that we lack primitives to ask whether an object (postgres would say relation) exists with a given name without specifying what type of object we want. This problem lies here:

cockroach/pkg/sql/sem/tree/name_resolution.go

Lines 253 to 262 in 3e4a440

	// DesiredObjectKind represents what kind of object is desired in a name
	// resolution attempt.
	type DesiredObjectKind int
	const (
	// TableObject is used when a table-like object is desired from resolution.
	TableObject DesiredObjectKind = iota
	// TypeObject is used when a type-like object is desired from resolution.
	TypeObject
	)

We probably need some sort of AnyObject here. That's all fine and good, but it gets a tad tricky here when we want to construct a name for the purposes of errors.

cockroach/pkg/sql/sem/tree/name_resolution.go

Lines 264 to 267 in 3e4a440

	// NewQualifiedObjectName returns an ObjectName of the corresponding kind.
	// It is used mainly for constructing appropriate error messages depending
	// on what kind of object was requested.
	func NewQualifiedObjectName(catalog, schema, object string, kind DesiredObjectKind) ObjectName {

At a deeper level, I don't really understand what value we get out of having different types for TableName and TypeName.

Jira issue: CRDB-11305

Epic CRDB-35306