Don't fail if multiple core version are found

use the latest one based on semver
a dependency was added (github.com/blang/semver), hopefully we'll use it somwhere else since it's really useful

Author: facchinm

src/arduino.cc/builder/constants/constants.go

@@ -213,6 +213,7 @@ const MSG_CANT_FIND_SKETCH_IN_PATH = "Unable to find {0} in {1}"
 const MSG_INVALID_QUOTING = "Invalid quoting: no closing [{0}] char found."
 const MSG_LIB_LEGACY = "(legacy)"
 const MSG_LIBRARIES_MULTIPLE_LIBS_FOUND_FOR = "Multiple libraries were found for \"{0}\""
+const MSG_CORES_MULTIPLE_CORES_FOUND_FOR = "Multiple versions of {0} core were found, using {1}"
 const MSG_LIBRARIES_NOT_USED = " Not used: {0}"
 const MSG_LIBRARIES_USED = " Used: {0}"
 const MSG_LIBRARY_CAN_USE_SRC_AND_UTILITY_FOLDERS = "Library can't use both 'src' and 'utility' folders. Double check {0}"

src/arduino.cc/builder/hardware_loader.go

@@ -84,7 +84,7 @@ func (s *HardwareLoader) Run(context map[string]interface{}) error {
 			}
 
 			targetPackage := getOrCreatePackage(packages, packageId)
-			err = loadPackage(targetPackage, subfolderPath, logger)
+			err = loadPackage(targetPackage, subfolderPath, logger, context)
 			if err != nil {
 				return utils.WrapError(err)
 			}
@@ -110,7 +110,7 @@ func getOrCreatePackage(packages *types.Packages, packageId string) *types.Packa
 	return &targetPackage
 }
 
-func loadPackage(targetPackage *types.Package, folder string, logger i18n.Logger) error {
+func loadPackage(targetPackage *types.Package, folder string, logger i18n.Logger, context map[string]interface{}) error {
 	packagePlatformTxt, err := props.SafeLoad(filepath.Join(folder, constants.FILE_PLATFORM_TXT), logger)
 	if err != nil {
 		return utils.WrapError(err)
@@ -131,9 +131,14 @@ func loadPackage(targetPackage *types.Package, folder string, logger i18n.Logger
 
 		_, err := os.Stat(filepath.Join(subfolderPath, constants.FILE_BOARDS_TXT))
 		if err != nil && os.IsNotExist(err) {
-			theOnlySubfolder, err := utils.TheOnlySubfolderOf(subfolderPath)
+			theOnlySubfolder, err := utils.TheBestSubfolderOf(subfolderPath)
 			if err != nil {
-				return utils.WrapError(err)
+				if theOnlySubfolder != constants.EMPTY_STRING {
+					logger := context[constants.CTX_LOGGER].(i18n.Logger)
+					logger.Fprintln(os.Stdout, constants.LOG_LEVEL_WARN, constants.MSG_CORES_MULTIPLE_CORES_FOUND_FOR, platformId, err.Error())
+				} else {
+					return utils.WrapError(err)
+				}
 			}
 
 			if theOnlySubfolder != constants.EMPTY_STRING {

src/arduino.cc/builder/utils/utils.go

@@ -36,6 +36,7 @@ import (
 	"arduino.cc/builder/types"
 	"crypto/md5"
 	"encoding/hex"
+	"github.com/blang/semver"
 	"github.com/go-errors/errors"
 	"io/ioutil"
 	"os"
@@ -358,17 +359,29 @@ func ReadFileToRows(file string) ([]string, error) {
 	return strings.Split(txt, "\n"), nil
 }
 
-func TheOnlySubfolderOf(folder string) (string, error) {
+func TheBestSubfolderOf(folder string) (string, error) {
 	subfolders, err := ReadDirFiltered(folder, FilterDirs)
 	if err != nil {
 		return constants.EMPTY_STRING, WrapError(err)
 	}
 
-	if len(subfolders) != 1 {
+	if len(subfolders) > 0 {
+		latest, _ := semver.Make(subfolders[0].Name())
+		latest_index := 0
+		for i, _ := range subfolders {
+			test, _ := semver.Make(subfolders[i].Name())
+			if test.GT(latest) {
+				latest = test
+				latest_index = i
+			}
+		}
+		if len(subfolders) > 1 {
+			err = errors.New(subfolders[latest_index].Name())
+		}
+		return subfolders[latest_index].Name(), err
+	} else {
 		return constants.EMPTY_STRING, nil
 	}
-
-	return subfolders[0].Name(), nil
 }
 
 func FilterOutFoldersByNames(folders []os.FileInfo, names ...string) []os.FileInfo {