Querying does not always work as it should

[indiejames]

I find that queries sometimes work as expected, but sometimes do not. For example in the following code:

package main

import (
	"context"
	"fmt"

	sitter "github.com/smacker/go-tree-sitter"
	"github.com/smacker/go-tree-sitter/golang"
)

var source = []byte(`package main

import "fmt"
// A comment
func main() {
	fmt.Println("Hello, world!")
}`)

func walkTree(node *sitter.Node, code []byte, depth int) {
	count := node.ChildCount()
	var childCount int = int(count)
	var tabs string = ""
	if depth > 0 {
		tabs = "│\n├"
	}
	for i := 0; i < depth; i++ {
		tabs = tabs + "──"
	}
	t := node.Type()
	if t == "\n" {
		t = ""
	}
	parentType := "nil"
	if node.Parent() != nil {
		parentType = node.Parent().Type()
	}
	fmt.Printf("%s Type: %s Parent Type: %s Text: %s\n", tabs, t, parentType, code[node.StartByte():node.EndByte()])
	for i := 0; i < childCount; i++ {
		walkTree(node.Child(i), code, depth+1)
	}
}

func main() {
	prs := sitter.NewParser()
	lng := golang.GetLanguage()
	prs.SetLanguage(lng)
	t, _ := prs.ParseCtx(context.Background(), nil, source)
	q1, _ := sitter.NewQuery([]byte("(comment)"), lng)
	nd := t.RootNode()

	fmt.Println("========= COMMENTS ==========")
	crs := sitter.NewQueryCursor()
	crs.Exec(q1, nd)
	m1, _ := crs.NextMatch()
	fmt.Printf("m1.Captures: %v\n\n", m1.Captures)

	fmt.Println("========= TREE ==========")
	walkTree(nd, source, 0)

}

This tries to query using `(comment)`, then it walks the tree printing out the nodes.

The abridged output is the following:

========= COMMENTS ==========
m1.Captures: []

========= TREE ==========
Type: source_file Parent Type: nil Text: package main

import "fmt"
// A comment
func main() {
fmt.Println("Hello, world!")
}
│
├── Type: package_clause Parent Type: source_file Text: package main
│
├──── Type: package Parent Type: package_clause Text: package
│
├──── Type: package_identifier Parent Type: package_clause Text: main
│
├── Type: Parent Type: source_file Text:

...

├── Type: comment Parent Type: source_file Text: // A comment

...

You can see that the parsing sees the node of type `comment` is there, but the query using `(comment`) doesn't return any captures.

Some of the other queries I have tried work, some do not.

The `(comment)` query is taking from the `.scm` file in the tree sitter queries provided with the helix editor.

Am I doing something wrong, or is this a bug?

[indiejames]

Curious, I find now that if I query with (comment) @comment instead of just (comment) it does work. Apparently the tag is required. I'll close this ticket I guess.