Simple explicit stack trace

trace.go

package main

import (
	"errors"
	"fmt"
	"runtime"
	"strings"
)

// f1 call f2() and show the trace
func f1() error {
	err := f2()
	if err != nil {
		return Tracef("f1 call f2: %trace %v", err)
	}
	return nil
}

// f2 call notrace() and show the trace
func f2() error {
	err := notrace()
	if err != nil {
		return Tracef("f2 call notrace: %trace %v", err)
	}
	return nil
}

// notrace don't show any trace
func notrace() error {
	return errors.New("simple error with no trace")
}

func main() {
	fmt.Println(f1())
}

// Wrapf return formated error with added %trace and %w
func Wrapf(err error, s string, vals ...any) error {
	vals = append(vals, err)
	return linef(2, s+"\n%trace%w", vals...)
}

// Tracef replace %trace by func() file:line
// fmt.Errorf("blabla %trace %w") will output
// blabla method() file:line %w
func Tracef(s string, vals ...any) error {
	return linef(2, s, vals...)
}

// linef replace %trace with method + file:line
func linef(skip int, s string, vals ...any) error {
	pc, file, line, ok := runtime.Caller(skip)
	if ok {
		info := fmt.Sprintf("\n> %s()\n> %s:%d\n",
			runtime.FuncForPC(pc).Name(), file, line)
		s = strings.Replace(s, "%trace", info, 1)
	}
	return fmt.Errorf(s, vals...)
}