16.go

     1  // run
     2  
     3  // Copyright 2022 The Go Authors. All rights reserved.
     4  // Use of this source code is governed by a BSD-style
     5  // license that can be found in the LICENSE file.
     6  
     7  // Test that type assertion panics mention the real interface type,
     8  // not their shape type.
     9  
    10  package main
    11  
    12  import (
    13  	"fmt"
    14  	"runtime"
    15  	"strings"
    16  )
    17  
    18  func main() {
    19  	// The exact error message isn't important, but it should mention
    20  	// `main.T`, not `go.shape.int_0`.
    21  	if have := F[T](); !strings.Contains(have, "interface { T() main.T }") {
    22  		fmt.Printf("FAIL: unexpected panic message: %q\n", have)
    23  	}
    24  }
    25  
    26  type T int
    27  
    28  func F[T any]() (res string) {
    29  	defer func() {
    30  		res = recover().(runtime.Error).Error()
    31  	}()
    32  	_ = interface{ T() T }(nil).(T)
    33  	return
    34  }
    35
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