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go/types: Alias.String should not mention the aliased type #64584

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adonovan opened this issue Dec 6, 2023 · 2 comments
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go/types: Alias.String should not mention the aliased type #64584

adonovan opened this issue Dec 6, 2023 · 2 comments
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NeedsFix The path to resolution is known, but the work has not been done.
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@adonovan
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adonovan commented Dec 6, 2023

The current behavior of the new go/types.Alias.String method is to print the aliased type in a comment, but I'm not convinced it should. We don't do this for named types, and it undermines one of the main benefits of aliases, which is brevity. The alias name alone seems clear enough, as it's what appears in the source.

@gri @findleyr

$ go build -o alias ./alias.go
$ ./alias
func([]int)
$ GODEBUG=gotypesalias=1  ./alias 
func([]command-line-arguments.A /* = int */)
package main

import (
	"fmt"
	"log"
	"os"

	"golang.org/x/tools/go/packages"
)

type A = int

var x func([]A)

func main() {
	cfg := &packages.Config{Mode: packages.LoadAllSyntax}
	pkgs, err := packages.Load(cfg, "./alias.go")
	if err != nil {
		log.Fatal(err)
	}
	if packages.PrintErrors(pkgs) > 0 {
		os.Exit(1)
	}
	fmt.Println(pkgs[0].Types.Scope().Lookup("x").Type())
}
@griesemer griesemer self-assigned this Dec 6, 2023
@griesemer griesemer added this to the Go1.22 milestone Dec 6, 2023
@adonovan
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adonovan commented Dec 6, 2023

Also: an alias of an alias doesn't nest correctly:

type C = int
type B = []C
type A = B
var x func([]A)

=>

func([]command-line-arguments.A /* = []command-line-arguments.C /* = int */ */)    !!

@gopherbot
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Change https://go.dev/cl/548135 mentions this issue: go/types, types2: don't print aliased type (in comments) for Alias types

@dmitshur dmitshur added the NeedsFix The path to resolution is known, but the work has not been done. label Dec 20, 2023
ezz-no pushed a commit to ezz-no/go-ezzno that referenced this issue Feb 18, 2024
Fixes golang#64584.

Change-Id: I756d6026d10f130c1dd5026891b7cc3c640d7f78
Reviewed-on: https://go-review.googlesource.com/c/go/+/548135
Reviewed-by: Alan Donovan <adonovan@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
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