pkg/proc: failed to call method on struct type: write out of bounds

[ZekeLu]

1. What version of Delve are you using (dlv version)?

Delve Debugger
Version: 1.20.2
Build: $Id: e0c278ad8e0126a312b553b8e171e81bcbd37f60 $

2. What version of Go are you using? (go version)?

go version go1.20.4 linux/amd64

3. What operating system and processor architecture are you using?

linux/amd64

5. What did you do?

Take the following program:

package main

import (
	"fmt"
	"runtime"
)

type T struct {
	a int
	b uint32
}

func (t T) String() string {
	return fmt.Sprintf("%d %d", t.a, t.b)
}

func main() {
	t := T{a: 1, b: 2}
	runtime.Breakpoint()
	fmt.Println(t.String())
}

and ran:

dlv debug
(dlv) c
(dlv) call t.String()

6. What did you expect to see?

(dlv) call t.String()
> main.main() ./main.go:20 (PC: 0x49ecbf)
Values returned:
	~r0: "1 2"

7. What did you see instead?

(dlv) call t.String()
> main.main() ./main.go:20 (PC: 0x49ecbf)
Command failed: write out of bounds

PS:

This bug is based on a real use case to print the value of github.com/shopspring/decimal.Decimal. This is the definition of decimal.Decimal:

type Decimal struct {
	value *big.Int
	exp int32
}

See also this question https://stackoverflow.com/questions/76222724/is-it-possible-to-preview-github-com-shopspring-decimal-values-in-vscode-during.