deriveSorted does not handle type aliases for elements

[deosjr]

Consider the following program

package main

import (
    "fmt"
)

type X struct {}

type Y int

type Z map[Y]*X

func test(z Z) {
    for _, k := range deriveSorted(deriveKeys(z)) {
        fmt.Println(z[k])
    }
}

func main() {
    z := map[Y]*X{}
    test(z)
    fmt.Println("Succes")
}

Running goderive runs fine, but subsequently the program fails to compile, with the following error:

./derived.gen.go:11:11: cannot use list (type []Y) as type []int in argument to sort.Ints

deriveSorted has been generated as:

func deriveSorted(list []Y) []Y {
    sort.Ints(list)
    return list
}

and it is sort.Ints that is throwing the error

[awalterschulze]

Good catch. Yes deriveSort should be made to be able to generate this without an error. Thank you for reporting. I clearly didn't test type aliases enough :)

[deosjr]

I don't think I'll be diving into this deep enough to fix it. Did create a few test cases to illustrate, which I include here

type stringalias string

func TestSortedMapKeysTypeAliasKey(t *testing.T) {
    var m map[stringalias]string
    m = random(m).(map[stringalias]string)
    keys := deriveSortedAlias(deriveKeysForMapAliasToString(m))

This test case will fail because of the stated issue: deriveSortedAlias is never generated. The analogous TestSortedMapKeysTypeAliasValue does succeed but is currently missing from the test suite.

func TestSortedMapKeysTypeAliasInScope(t *testing.T) {
    type stringalias string
    var m map[string]stringalias
    m = random(m).(map[string]stringalias)
    keys := deriveSorted(deriveKeysForMapStringToAlias(m))

This test I made by mistake, and fails for a different reason. deriveSorted is generated, but the alias is only defined in scope of the test. Running goderive therefore succeeds but the program won't compile.

[awalterschulze]

No problem. The report is already very helpful, thank you :) Especially providing test cases, is even more useful. Thanks for all your help here.