mono_test.go

     1  // Copyright 2021 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package types_test
     6  
     7  import (
     8  	"errors"
     9  	"fmt"
    10  	"go/importer"
    11  	"go/types"
    12  	"strings"
    13  	"testing"
    14  )
    15  
    16  func checkMono(t *testing.T, body string) error {
    17  	src := "package x; import `unsafe`; var _ unsafe.Pointer;\n" + body
    18  
    19  	var buf strings.Builder
    20  	conf := types.Config{
    21  		Error:    func(err error) { fmt.Fprintln(&buf, err) },
    22  		Importer: importer.Default(),
    23  	}
    24  	typecheck(src, &conf, nil)
    25  	if buf.Len() == 0 {
    26  		return nil
    27  	}
    28  	return errors.New(strings.TrimRight(buf.String(), "\n"))
    29  }
    30  
    31  func TestMonoGood(t *testing.T) {
    32  	for i, good := range goods {
    33  		if err := checkMono(t, good); err != nil {
    34  			t.Errorf("%d: unexpected failure: %v", i, err)
    35  		}
    36  	}
    37  }
    38  
    39  func TestMonoBad(t *testing.T) {
    40  	for i, bad := range bads {
    41  		if err := checkMono(t, bad); err == nil {
    42  			t.Errorf("%d: unexpected success", i)
    43  		} else {
    44  			t.Log(err)
    45  		}
    46  	}
    47  }
    48  
    49  var goods = []string{
    50  	"func F[T any](x T) { F(x) }",
    51  	"func F[T, U, V any]() { F[U, V, T](); F[V, T, U]() }",
    52  	"type Ring[A, B, C any] struct { L *Ring[B, C, A]; R *Ring[C, A, B] }",
    53  	"func F[T any]() { type U[T any] [unsafe.Sizeof(F[*T])]byte }",
    54  	"func F[T any]() { type U[T any] [unsafe.Sizeof(F[*T])]byte; var _ U[int] }",
    55  	"type U[T any] [unsafe.Sizeof(F[*T])]byte; func F[T any]() { var _ U[U[int]] }",
    56  	"func F[T any]() { type A = int; F[A]() }",
    57  }
    58  
    59  // TODO(mdempsky): Validate specific error messages and positioning.
    60  
    61  var bads = []string{
    62  	"func F[T any](x T) { F(&x) }",
    63  	"func F[T any]() { F[*T]() }",
    64  	"func F[T any]() { F[[]T]() }",
    65  	"func F[T any]() { F[[1]T]() }",
    66  	"func F[T any]() { F[chan T]() }",
    67  	"func F[T any]() { F[map[*T]int]() }",
    68  	"func F[T any]() { F[map[error]T]() }",
    69  	"func F[T any]() { F[func(T)]() }",
    70  	"func F[T any]() { F[func() T]() }",
    71  	"func F[T any]() { F[struct{ t T }]() }",
    72  	"func F[T any]() { F[interface{ t() T }]() }",
    73  	"type U[_ any] int; func F[T any]() { F[U[T]]() }",
    74  	"func F[T any]() { type U int; F[U]() }",
    75  	"func F[T any]() { type U int; F[*U]() }",
    76  	"type U[T any] int; func (U[T]) m() { var _ U[*T] }",
    77  	"type U[T any] int; func (*U[T]) m() { var _ U[*T] }",
    78  	"type U[T1 any] [unsafe.Sizeof(F[*T1])]byte; func F[T2 any]() { var _ U[T2] }",
    79  	"func F[A, B, C, D, E any]() { F[B, C, D, E, *A]() }",
    80  	"type U[_ any] int; const X = unsafe.Sizeof(func() { type A[T any] U[A[*T]] })",
    81  	"func F[T any]() { type A = *T; F[A]() }",
    82  	"type A[T any] struct { _ A[*T] }",
    83  }
    84
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