Panic on doc generate when using middleware.Profiler

[zbindenren]

Hi

When using the profiler middleware in combination with the docgen package, I get a panic.

main.go:

...
func main() {
        flag.Parse()

        r := chi.NewRouter()

        r.Use(middleware.RequestID)
        r.Use(middleware.Logger)
        r.Use(middleware.Recoverer)
        r.Mount("/debug", middleware.Profiler()) // <- this is new

        r.Get("/", func(w http.ResponseWriter, r *http.Request) {
                w.Write([]byte("root."))
        })
...

panic:

panic: reflect: call of reflect.Value.Pointer on string Value

goroutine 1 [running]:
panic(0x754b80, 0xc420323300)
        /usr/lib/go/src/runtime/panic.go:500 +0x1a1
reflect.Value.Pointer(0x750660, 0xc420120150, 0x98, 0xc420120150)
        /usr/lib/go/src/reflect/value.go:1258 +0x12f
github.com/pressly/chi/docgen.getCallerFrame(0x750660, 0xc420120150, 0x5)
        /home/rz/golang/src/github.com/pressly/chi/docgen/util.go:11 +0x6f
github.com/pressly/chi/docgen.buildFuncInfo(0x750660, 0xc420120150, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
        /home/rz/golang/src/github.com/pressly/chi/docgen/builder.go:85 +0x8e
github.com/pressly/chi/docgen.buildDocRouter(0x7fab6d6e30b0, 0xc420128120, 0xc4202f2f60, 0x0, 0xc4202f2f60, 0xc420211650)
        /home/rz/golang/src/github.com/pressly/chi/docgen/builder.go:71 +0x895
github.com/pressly/chi/docgen.buildDocRouter(0x7fab6d6e30b0, 0xc4201280c0, 0xc42000c0c7, 0xf, 0x7af600, 0x956700)
        /home/rz/golang/src/github.com/pressly/chi/docgen/builder.go:45 +0x3fd
github.com/pressly/chi/docgen.BuildDoc(0x7fab6d6e30b0, 0xc4201280c0, 0xc4201280c0, 0x7fab6d6e30b0, 0xc4201280c0, 0x8, 0xc42004de98, 0x4eb52c)
        /home/rz/golang/src/github.com/pressly/chi/docgen/builder.go:23 +0xf4
github.com/pressly/chi/docgen.(*MarkdownDoc).Generate(0xc420183e18, 0xc420135900, 0x3ff)
        /home/rz/golang/src/github.com/pressly/chi/docgen/markdown.go:56 +0x6d
github.com/pressly/chi/docgen.MarkdownRoutesDoc(0x95e0e0, 0xc4201280c0, 0x7c7251, 0x16, 0x7d1103, 0x31, 0x0, 0x0, 0x1d, 0x0)
        /home/rz/golang/src/github.com/pressly/chi/docgen/markdown.go:41 +0x9c
main.main()
        /tmp/bla/main.go:67 +0x29b

[pkieltyka]

Im unable to reproduce the above issue with the latest master, but if you see it comes up again please re-open the ticket and I'll take a look asap.

[zbindenren]

@pkieltyka I have the same issue with the latest releases. I opened the issue with the reproducer for the docgen repo here.

[ladydascalie]

I have this issue as well on the latest releases

[VojtechVitek]

Do you guys have full reproducer?

[ladydascalie]

@VojtechVitek the following contrived example shows the exact panic received:

main.go:

package main

import (
	"net/http"

	"github.com/go-chi/chi"
	"github.com/go-chi/chi/middleware"
	"github.com/go-chi/docgen"
)

func main() {
	r := chi.NewRouter()
	r.Mount("/debug", middleware.Profiler())
	r.Get("/bla", blaHandler)

	docgen.JSONRoutesDoc(r)

	http.ListenAndServe(":8080", r)
}

func blaHandler(w http.ResponseWriter, r *http.Request) {
	w.WriteHeader(204)
}

trace:

panic: reflect: call of reflect.Value.Pointer on string Value

goroutine 1 [running]:
reflect.Value.Pointer(0x138b5c0, 0xc420010cc0, 0x98, 0xc420010cc0)
	/usr/local/go/src/reflect/value.go:1276 +0x185
github.com/go-chi/docgen.getCallerFrame(0x138b5c0, 0xc420010cc0, 0x16117a0)
	/Users/benjamincable/go/src/github.com/go-chi/docgen/funcinfo.go:70 +0x6f
github.com/go-chi/docgen.buildFuncInfo(0x138b5c0, 0xc420010cc0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/Users/benjamincable/go/src/github.com/go-chi/docgen/builder.go:85 +0x91
github.com/go-chi/docgen.buildDocRouter(0x15e3d20, 0xc4201380e0, 0xc420081b30, 0x0, 0xc420081b30, 0xf)
	/Users/benjamincable/go/src/github.com/go-chi/docgen/builder.go:71 +0x7f3
github.com/go-chi/docgen.buildDocRouter(0x15e3d20, 0xc420138070, 0xc42001a1a7, 0x17, 0x4, 0x15e0a20)
	/Users/benjamincable/go/src/github.com/go-chi/docgen/builder.go:45 +0x427
github.com/go-chi/docgen.BuildDoc(0x15e3d20, 0xc420138070, 0x3ff, 0x15e3d20, 0xc4201380e0, 0xc4201380e0, 0xc42012bf28, 0x12ab7ce)
	/Users/benjamincable/go/src/github.com/go-chi/docgen/builder.go:23 +0xf4
github.com/go-chi/docgen.JSONRoutesDoc(0x15e3d20, 0xc420138070, 0x4, 0x141e7e0)
	/Users/benjamincable/go/src/github.com/go-chi/docgen/docgen.go:58 +0x42
main.main()
	/Users

[pkieltyka]

@ladydascalie I've tried to run your example using chi v3.3.1 on go 1.9.2 and couldn't reproduce the issue - the docs generated fine. Would you mind confirming when you have a chance?

[ladydascalie]

Sorry, I missed the notification for this before.

Running it on the latest version works properly for me!

[pkieltyka]

@ladydascalie awesome thanks for confirming!