catalog: Improve variadic argument support (#804)

Author: kyleconroy

Makefile

@@ -1,4 +1,4 @@
-.PHONY: build test test-examples regen
+.PHONY: build test test-examples regen start psql mysqlsh
 
 build:
 	go build ./...
@@ -17,3 +17,12 @@ sqlc-dev:
 
 sqlc-pg-gen:
 	go build -o ~/bin/sqlc-pg-gen ./internal/tools/sqlc-pg-gen
+
+start:
+	docker-compose up -d
+
+psql:
+	PGPASSWORD=mysecretpassword psql --host=127.0.0.1 --port=5432 --username=postgres dinotest
+
+mysqlsh:
+	mysqlsh --sql --user root --password mysecretpassword --database dinotest 127.0.0.1:3306

internal/endtoend/testdata/json_build/go/query.sql.go

@@ -1,12 +1,14 @@
 -- name: SelectJSONBuildObject :one
 SELECT
+  json_build_object(),
   json_build_object('foo'),
   json_build_object('foo', 1),
   json_build_object('foo', 1, 2),
   json_build_object('foo', 1, 2, 'bar');
 
 -- name: SelectJSONBuildArray :one
 SELECT 
+  json_build_array(),
   json_build_array(1),
   json_build_array(1, 2),
   json_build_array(1, 2, 'foo'),

internal/endtoend/testdata/json_build/query.sql

@@ -251,7 +251,6 @@ type Argument struct {
 	Name       string
 	Type       *ast.TypeName
 	HasDefault bool
-	Variadic   bool
 	Mode       ast.FuncParamMode
 }
 

internal/engine/postgresql/pg_catalog.go

@@ -72,17 +72,17 @@ func (c *Catalog) ResolveFuncCall(call *ast.FuncCall) (*Function, error) {
 			if arg.HasDefault {
 				defaults += 1
 			}
-			if arg.Variadic {
+			if arg.Mode == ast.FuncParamVariadic {
 				variadic = true
+				defaults += 1
 			}
 			if arg.Name != "" {
 				known[arg.Name] = struct{}{}
 			}
 		}
 
 		if variadic {
-			// For now, assume variadic fucntions can't also have defaults
-			if (len(named) + len(positional)) < len(args) {
+			if (len(named) + len(positional)) < (len(args) - defaults) {
 				continue
 			}
 		} else {