Some 'index out of range' error in tree.go

[cainmusic]

Router tree bug

when add a catch-all router, there may be an error reported:

panic: runtime error: index out of range [0] with length 0

How to reproduce

package main

import (
	"github.com/gin-gonic/gin"
)

func main() {
	r := gin.Default()

	r.GET("/static/", func(c *gin.Context) { c.String(200, "static") })
	r.GET("/static/*file", func(c *gin.Context) { c.String(200, "static file") })

	r.Run()
}

Source code

tree.go

		if len(n.path) > 0 && n.path[len(n.path)-1] == '/' {
			pathSeg := strings.SplitN(n.children[0].path, "/", 2)[0]
			panic("catch-all wildcard '" + path +
				"' in new path '" + fullPath +
				"' conflicts with existing path segment '" + pathSeg +
				"' in existing prefix '" + n.path + pathSeg +
				"'")
		}

this line pathSeg := strings.SplitN(n.children[0].path, "/", 2)[0]

actually, n node do not have any children.

Environment

• go version: go1.20
• gin version (or commit ref): v1.9.1
• operating system: mac os

[cainmusic]

i thought:
if len(n.path) > 0 && n.path[len(n.path)-1] == '/' { should be i == 0
n.children[0].path should be n.path

[FirePing32]

The below line expects that the path will end with a wildcard name.

gin/tree.go

Line 354 in 53fbf4d

pathSeg := strings.SplitN(n.children[0].path, "/", 2)[0]

/static/*file is already a catch-all wildcard. You are trying to initialize a path /static/ (notice the trailing slash). This path is already a type of catch-all wildcard with no child paths, which leads to the conflict.
WIll open a PR by today EOD to fix this.