sql/catalog: Add support for variadic functions (#798)

* sql/catalog: Add support for variadic functions

Author: kyleconroy

internal/endtoend/testdata/json_build/go/db.go

@@ -0,0 +1,13 @@
+-- name: SelectJSONBuildObject :one
+SELECT
+  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(1),
+  json_build_array(1, 2),
+  json_build_array(1, 2, 'foo'),
+  json_build_array(1, 2, 'foo', 4);

internal/endtoend/testdata/json_build/go/models.go

@@ -0,0 +1,12 @@
+{
+  "version": "1",
+  "packages": [
+    {
+      "path": "go",
+      "engine": "postgresql",
+      "name": "querytest",
+      "schema": "query.sql",
+      "queries": "query.sql"
+    }
+  ]
+}

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

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

internal/endtoend/testdata/json_build/query.sql

@@ -66,20 +66,32 @@ func (c *Catalog) ResolveFuncCall(call *ast.FuncCall) (*Function, error) {
 	for _, fun := range funs {
 		args := fun.InArgs()
 		var defaults int
+		var variadic bool
 		known := map[string]struct{}{}
 		for _, arg := range args {
 			if arg.HasDefault {
 				defaults += 1
 			}
+			if arg.Variadic {
+				variadic = true
+			}
 			if arg.Name != "" {
 				known[arg.Name] = struct{}{}
 			}
 		}
-		if (len(named) + len(positional)) > len(args) {
-			continue
-		}
-		if (len(named) + len(positional)) < (len(args) - defaults) {
-			continue
+
+		if variadic {
+			// For now, assume variadic fucntions can't also have defaults
+			if (len(named) + len(positional)) < len(args) {
+				continue
+			}
+		} else {
+			if (len(named) + len(positional)) > len(args) {
+				continue
+			}
+			if (len(named) + len(positional)) < (len(args) - defaults) {
+				continue
+			}
 		}
 
 		// Validate that the provided named arguments exist in the function