Invalid behavior in some functions with return parameters

[zapateo]

Source code

package main

import (
        "fmt"
)

func f() (err error) {
        defer func() {
                _ = recover()
        }()
        var i int
        _ = 1 / i
        return nil
}

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

Scriggo output

runtime error: integer divide by zero

gc output

<nil>

[gazerro]

The function f does not panic, it returns the value returned from the recover built-in instead of nil.

The disassembled code is

Package main

Func f() (g1 error)
	; regs(3,0,0,3)
	Move nil g2
	Move g2 g1
	Func g3 func()
		; regs(0,0,0,1)
		Recover g1   <-- ERROR: it writes into register g1 which is the named result
		Return
	Move g3 g2
	Defer g2 _ _ _ _	; func()
	Move 0 i1
	Load 1 i3
	Div i3 i1 i2
	Move nil g2
	Move g2 g1
	Return
	Return

Func main()
	; regs(0,0,0,2)
	Call main.f _ _ _ g1	; func() (g1 error)
	Move g1 g2
	Print g2
	Typify string "\n" g1
	Print g1
	Return

The error is not due to the recover built-in. Replacing it with the make built-in, the error is the same:

package main

func f() (err error) {
        defer func() {
                _ = make([]int, 1)
        }()
        return nil
}

func main() {
        println(f())
}

and disassembled:

Package main

Func f() (g1 error)
	; regs(0,0,0,3)
	Move nil g2
	Move g2 g1
	Func g3 func()
		; regs(0,0,0,1)
		MakeSlice int 1 1 g1   <-- ERROR: it writes into register g1 which is the named result
		Return
	Move g3 g2
	Defer g2 _ _ _ _	; func()
	Move nil g2
	Move g2 g1
	Return
	Return

Func main()
	; regs(0,0,0,2)
	Call main.f _ _ _ g1	; func() (g1 error)
	Move g1 g2
	Print g2
	Typify string "\n" g1
	Print g1
	Return

[zapateo]

Another version of this issue:

package main

import (
        "fmt"
)

func s() []int { return []int{} }

func f() (err error) {
        defer func() {
                _ = recover()
                _ = s()
        }()
        var i int
        _ = 1 / i
        return nil
}

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

Yet another version of the issue:

package main

import (
	"fmt"
)

func f() interface{} {
	defer func() {
		_ = []int{}
		recover()
	}()
	panic(0)
}

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

May be the problem related to the finalizer?

[zapateo]

A simplified version of the issue:

package main

import (
	"fmt"
)

func f() []int {

	defer func() {
		recover()
	}()
	panic("")

}

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