compiler: implement comparing channel values

compiler/compiler.go

@@ -1953,10 +1953,12 @@ func (c *Compiler) parseBinOp(op token.Token, typ types.Type, x, y llvm.Value, p
 		default:
 			return llvm.Value{}, c.makeError(pos, "binop on interface: "+op.String())
 		}
-	case *types.Map, *types.Pointer:
+	case *types.Chan, *types.Map, *types.Pointer:
 		// Maps are in general not comparable, but can be compared against nil
 		// (which is a nil pointer). This means they can be trivially compared
 		// by treating them as a pointer.
+		// Channels behave as pointers in that they are equal as long as they
+		// are created with the same call to make or if both are nil.
 		switch op {
 		case token.EQL: // ==
 			return c.builder.CreateICmp(llvm.IntEQ, x, y, ""), nil

testdata/channel.go

@@ -4,7 +4,7 @@ import "time"
 
 func main() {
 	ch := make(chan int)
-	println("len, cap of channel:", len(ch), cap(ch))
+	println("len, cap of channel:", len(ch), cap(ch), ch == nil)
 	go sender(ch)
 
 	n, ok := <-ch

testdata/channel.txt

@@ -1,4 +1,4 @@
-len, cap of channel: 0 0
+len, cap of channel: 0 0 false
 recv from open channel: 1 true
 received num: 2
 received num: 3