How to get the stack trace pointing to actual error reason

Question

Let\'s say I have some code like this:

value, err := some3rdpartylib.DoSomething()
if err != nil {
    panic(err)
}

In case err != ni

Answer 1

package main

import (
    "errors"
    "fmt"
)

func main() {
    value, err := DoSomething()
    if err != nil {
        panic(err)
    }
    fmt.Println(value)
}

func DoSomething() (string, error) {
    return "", errors.New("some error explanation here")
}

The problem is the standard package errors does not attach the stack trace at the point it occurs. You can use github.com/pkg/errors to do that:

package main

import (
    "github.com/pkg/errors"
    "fmt"
)

func main() {
    value, err := DoSomething()
    if err != nil {
        fmt.Printf("%+v", err)
    }
    fmt.Println(value)
}

func DoSomething() (string, error) {
    return "", errors.New("some error explanation here")
}

$ go run stacktrace.go
some error explanation here
main.DoSomething
    /Users/quanta/go/src/github.com/quantonganh/errors/stacktrace.go:18
main.main
    /Users/quanta/go/src/github.com/quantonganh/errors/stacktrace.go:10
runtime.main
    /usr/local/Cellar/go/1.15.2/libexec/src/runtime/proc.go:204
runtime.goexit
    /usr/local/Cellar/go/1.15.2/libexec/src/runtime/asm_amd64.s:1374

More details: https://dave.cheney.net/2016/06/12/stack-traces-and-the-errors-package

Answer 2

Take a look at https://github.com/ztrue/tracerr

I created this package in order to have both stack trace and source fragments to be able to debug faster and log errors with much more details.

Here is a code example:

package main

import (
    "io/ioutil"
    "github.com/ztrue/tracerr"
)

func main() {
    if err := read(); err != nil {
        tracerr.PrintSourceColor(err)
    }
}

func read() error {
    return readNonExistent()
}

func readNonExistent() error {
    _, err := ioutil.ReadFile("/tmp/non_existent_file")
    // Add stack trace to existing error, no matter if it's nil.
    return tracerr.Wrap(err)
}

And here is the output: