instantiated: connect stdout

instantiated.go

@@ -11,6 +11,10 @@ import (
 	"strings"
 )
 
+var (
+	Stdout io.Writer = nil
+)
+
 const (
 	instantiatedPrefix    = "instantiated '"
 	instantiatedSeparator = " -> "
@@ -104,6 +108,8 @@ func EvalInstantiated(ctx context.Context, installable string) ([]string, error)
 
 	cmd := exec.CommandContext(c,
 		"nix", "build", installable,
+		// since flakes are supposedly experimental
+		"--extra-experimental-features", "nix-command flakes",
 		// 'instantiated' messages  are only emitted when actually evaluating something
 		"--option", "eval-cache", "false",
 		// do not actually build anything
@@ -112,6 +118,7 @@ func EvalInstantiated(ctx context.Context, installable string) ([]string, error)
 		"-Lvvv",
 	)
 
+	cmd.Stdout = Stdout
 	stderr, err := cmd.StderrPipe()
 	if err != nil {
 		return nil, err