newt/cli: Add target info command

This command prints all target's packages that contain app.flags
field and it's values. In the future this command
might be extended to show other miscellaneous info about
specified target.

newt/cli/target_cmds.go

@@ -23,6 +23,7 @@ import (
 	"bytes"
 	"fmt"
 	"io/ioutil"
+	"mynewt.apache.org/newt/newt/ycfg"
 	"os"
 	"sort"
 	"strings"
@@ -249,6 +250,50 @@ func targetShowCmd(cmd *cobra.Command, args []string) {
 	}
 }
 
+func printCflags(appCflags []ycfg.YCfgEntry) {
+	for _, f := range appCflags {
+		if itfVals, ok := f.Value.([]interface{}); ok {
+			for _, itfVal := range itfVals {
+				if strVal, ok := itfVal.(string); ok {
+					fmt.Println(strVal)
+				}
+			}
+		}
+	}
+}
+
+func targetInfoCmd(cmd *cobra.Command, args []string) {
+	if len(args) < 1 {
+		NewtUsage(cmd,
+			util.NewNewtError("Must specify target name"))
+	}
+
+	TryGetProject()
+
+	b, err := TargetBuilderForTargetOrUnittest(args[0])
+	if err != nil {
+		NewtUsage(cmd, err)
+	}
+
+	if err := b.PrepBuild(); err != nil {
+		NewtUsage(nil, err)
+	}
+
+	fmt.Println("Packages containing app.cflags:")
+
+	for _, rpkg := range b.AppBuilder.SortedRpkgs() {
+		appCflags, err := rpkg.Lpkg.PkgY.Get("app.cflags", nil)
+		if err != nil {
+			NewtUsage(nil, err)
+		}
+		if appCflags != nil {
+			fmt.Println(rpkg.Lpkg.Name())
+			printCflags(appCflags)
+			fmt.Println("")
+		}
+	}
+}
+
 func targetListCmd(cmd *cobra.Command, args []string) {
 	TryGetProject()
 	targetNames := []string{}
@@ -937,6 +982,21 @@ func AddTargetCommands(cmd *cobra.Command) {
 		return append(targetList(), unittestList()...)
 	})
 
+	infoHelpText := "Shows which packages contain app cflags in the target specified " +
+		"by <target-name>."
+	infoHelpEx := "  newt target info <target-name>\n"
+	infoHelpEx += "  newt target info my_target1"
+
+	infoCmd := &cobra.Command{
+		Use:     "info",
+		Short:   "Show packages with global cflags",
+		Long:    infoHelpText,
+		Example: infoHelpEx,
+		Run:     targetInfoCmd,
+	}
+	targetCmd.AddCommand(infoCmd)
+	AddTabCompleteFn(infoCmd, targetList)
+
 	for _, cmd := range targetCfgCmdAll() {
 		targetCmd.AddCommand(cmd)
 	}