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go/test/typeparam/stringer.go
Dan Scales 12e15d430d [dev.typeparams] cmd/compile: handle calling a method on a type param in stenciling
- Have to delay the extra transformation on methods invoked on a type
   param, since the actual transformation (including path through
   embedded fields) will depend on the instantiated type. I am currently
   doing the transformation during the stencil substitution phase. We
   probably should have a separate pass after noder2 and stenciling,
   which drives the extra transformations that were in the old
   typechecker.

 - We handle method values (that are not called) and method calls. We
   don't currently handle method expressions.

 - Handle type substitution in function types, which is needed for
   function args in generic functions.

 - Added stringer.go and map.go tests, testing the above changes
   (including constraints with embedded interfaces).

Change-Id: I3831a937d2b8814150f75bebf9f23ab10b93fa00
Reviewed-on: https://go-review.googlesource.com/c/go/+/290550
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Dan Scales <danscales@google.com>
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Dan Scales <danscales@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
2021-02-10 01:44:48 +00:00

89 lines
1.6 KiB
Go

// run -gcflags=-G=3
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Test method calls on type parameters
package main
import (
"fmt"
"reflect"
"strconv"
)
// Simple constraint
type Stringer interface {
String() string
}
func stringify[T Stringer](s []T) (ret []string) {
for _, v := range s {
ret = append(ret, v.String())
}
return ret
}
type myint int
func (i myint) String() string {
return strconv.Itoa(int(i))
}
// Constraint with an embedded interface, but still only requires String()
type Stringer2 interface {
CanBeStringer2() int
SubStringer2
}
type SubStringer2 interface {
CanBeSubStringer2() int
String() string
}
func stringify2[T Stringer2](s []T) (ret []string) {
for _, v := range s {
ret = append(ret, v.String())
}
return ret
}
func (myint) CanBeStringer2() int {
return 0
}
func (myint) CanBeSubStringer2() int {
return 0
}
// Test use of method values that are not called
func stringify3[T Stringer](s []T) (ret []string) {
for _, v := range s {
f := v.String
ret = append(ret, f())
}
return ret
}
func main() {
x := []myint{myint(1), myint(2), myint(3)}
got := stringify(x)
want := []string{"1", "2", "3"}
if !reflect.DeepEqual(got, want) {
panic(fmt.Sprintf("Got %s, want %s", got, want))
}
got = stringify2(x)
if !reflect.DeepEqual(got, want) {
panic(fmt.Sprintf("Got %s, want %s", got, want))
}
got = stringify3(x)
if !reflect.DeepEqual(got, want) {
panic(fmt.Sprintf("Got %s, want %s", got, want))
}
}