main.go

     1  // Copyright 2026 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 main
     6  
     7  import (
     8  	"reflect"
     9  
    10  	"./a"
    11  	"./b"
    12  )
    13  
    14  // Comparing two interfaces whose dynamic type the compiler knows is
    15  // compiled to a direct comparison, so compare through a function that has
    16  // to go through the type descriptor at run time.
    17  //
    18  //go:noinline
    19  func eq(x, y any) bool { return x == y }
    20  
    21  func main() {
    22  	// main never mentions [2]a.K itself, so the only descriptors for it
    23  	// are the ones in packages a and b.
    24  	_ = a.Sink
    25  	x, y := b.Get(), b.Get()
    26  	if !reflect.TypeOf(x).Comparable() {
    27  		panic("descriptor for [2]a.K has no equality function")
    28  	}
    29  	if !eq(x, y) {
    30  		panic("[2]a.K values compare unequal")
    31  	}
    32  }
    33
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