issue6847.go

     1  // compile
     2  
     3  // Copyright 2014 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  // Issue 6847: select clauses involving implicit conversion
     8  // of channels trigger a spurious typechecking error during walk.
     9  
    10  package p
    11  
    12  type I1 interface {
    13  	String()
    14  }
    15  type I2 interface {
    16  	String()
    17  }
    18  
    19  func F() {
    20  	var (
    21  		cr <-chan int
    22  		cs chan<- int
    23  		c  chan int
    24  
    25  		ccr chan (<-chan int)
    26  		ccs chan chan<- int
    27  		cc  chan chan int
    28  
    29  		ok bool
    30  	)
    31  	// Send cases.
    32  	select {
    33  	case ccr <- cr:
    34  	case ccr <- c:
    35  	}
    36  	select {
    37  	case ccs <- cs:
    38  	case ccs <- c:
    39  	}
    40  	select {
    41  	case ccr <- c:
    42  	default:
    43  	}
    44  	// Receive cases.
    45  	select {
    46  	case cr = <-cc:
    47  	case cs = <-cc:
    48  	case c = <-cc:
    49  	}
    50  	select {
    51  	case cr = <-cc:
    52  	default:
    53  	}
    54  	select {
    55  	case cr, ok = <-cc:
    56  	case cs, ok = <-cc:
    57  	case c = <-cc:
    58  	}
    59        // Interfaces.
    60  	var (
    61  		c1 chan I1
    62  		c2 chan I2
    63  		x1 I1
    64  		x2 I2
    65  	)
    66  	select {
    67  	case c1 <- x1:
    68  	case c1 <- x2:
    69  	case c2 <- x1:
    70  	case c2 <- x2:
    71  	}
    72  	select {
    73  	case x1 = <-c1:
    74  	case x1 = <-c2:
    75  	case x2 = <-c1:
    76  	case x2 = <-c2:
    77  	}
    78  	select {
    79  	case x1, ok = <-c1:
    80  	case x1, ok = <-c2:
    81  	case x2, ok = <-c1:
    82  	case x2, ok = <-c2:
    83  	}
    84  	_ = ok
    85  }
    86
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