importer: IMPORT INTO ... DELIMITED DATA with collated strings does not work

[otan]

Running

create type countrylanguage_isofficial_enum as enum('T', 'F');                                              
CREATE TABLE public.countrylanguage (                                                                           
	countrycode VARCHAR(3) NOT NULL DEFAULT '':::STRING,                                                     
	language VARCHAR(30) COLLATE "en_US" NOT NULL DEFAULT '':::STRING,
	isofficial public.countrylanguage_isofficial_enum NOT NULL DEFAULT 'F':::public.countrylanguage_isofficial_enum,
	percentage DECIMAL(4,1) NOT NULL DEFAULT 0.0:::DECIMAL,                                                              
	CONSTRAINT countrylanguage_pkey PRIMARY KEY (countrycode ASC, language ASC),                           
	INDEX countrycode (countrycode ASC, language ASC)
);
 IMPORT INTO countrylanguage
 DELIMITED DATA (                                                                 
 'https://cockroachdb-migration-examples.s3.us-east-1.amazonaws.com/mysql/world-data/countrylanguage.txt'                   
 )	WITH
 	fields_enclosed_by='"',
	 fields_escaped_by='\';

Yields

ERROR: https://cockroachdb-migration-examples.s3.us-east-1.amazonaws.com/mysql/world-data/countrylanguage.txt: error parsing row 1: error while parse "language" as VARCHAR(30) COLLATE en_US: column "dutch" does not exist (row: "ABW"	"Dutch"	"T"	"5.3")

But insert into countrylanguage values ('ABW', 'Dutch', 'T', 5.3); works, as does removing COLLATE "en_US" from the column definition.

Jira issue: CRDB-30257

[otan]

sample of countrylanguage.txt, in case it gets lost:

"ABW"	"Dutch"	"T"	"5.3"
"ABW"	"English"	"F"	"9.5"
"ABW"	"Papiamento"	"F"	"76.7"
"ABW"	"Spanish"	"F"	"7.4"
"AFG"	"Balochi"	"F"	"0.9"
"AFG"	"Dari"	"T"	"32.1"

[otan]

Problem is the use of parser.ParseExpr in parseAsTyp for CollatedString:

cockroach/pkg/sql/rowenc/roundtrip_format.go

Lines 57 to 62 in fc1fa24

	expr, err := parser.ParseExpr(s)
	if err != nil {
	return nil, err
	}
	semaCtx := tree.MakeSemaContext()
	typedExpr, err := tree.TypeCheck(ctx, expr, &semaCtx, typ)

seems to think this is a tree.UnresolvedName which is correct. not sure why ParseDatumAsString handles collated strings through parseAsTyp though:

cockroach/pkg/sql/rowenc/roundtrip_format.go

Lines 29 to 32 in fc1fa24

	// the internal postgres string representation of arrays.
	case types.ArrayFamily, types.CollatedStringFamily:
	return parseAsTyp(ctx, evalCtx, t, s)
	default: