1 files changed, 31 insertions, 11 deletions

diff --git a/vendor/golang.org/x/tools/go/buildutil/tags.go b/vendor/golang.org/x/tools/go/buildutil/tags.go
index 7cf523bca..32c8d1424 100644
--- a/vendor/golang.org/x/tools/go/buildutil/tags.go
+++ b/vendor/golang.org/x/tools/go/buildutil/tags.go
@@ -4,17 +4,22 @@
 
 package buildutil
 
-// This logic was copied from stringsFlag from $GOROOT/src/cmd/go/build.go.
+// This duplicated logic must be kept in sync with that from go build:
+//   $GOROOT/src/cmd/go/internal/work/build.go (tagsFlag.Set)
+//   $GOROOT/src/cmd/go/internal/base/flag.go (StringsFlag.Set)
+//   $GOROOT/src/cmd/internal/quoted/quoted.go (isSpaceByte, Split)
 
-import "fmt"
+import (
+	"fmt"
+	"strings"
+)
 
 const TagsFlagDoc = "a list of `build tags` to consider satisfied during the build. " +
 	"For more information about build tags, see the description of " +
 	"build constraints in the documentation for the go/build package"
 
 // TagsFlag is an implementation of the flag.Value and flag.Getter interfaces that parses
-// a flag value in the same manner as go build's -tags flag and
-// populates a []string slice.
+// a flag value the same as go build's -tags flag and populates a []string slice.
 //
 // See $GOROOT/src/go/build/doc.go for description of build tags.
 // See $GOROOT/src/cmd/go/doc.go for description of 'go build -tags' flag.
@@ -25,19 +30,32 @@ const TagsFlagDoc = "a list of `build tags` to consider satisfied during the bui
 type TagsFlag []string
 
 func (v *TagsFlag) Set(s string) error {
-	var err error
-	*v, err = splitQuotedFields(s)
-	if *v == nil {
-		*v = []string{}
+	// See $GOROOT/src/cmd/go/internal/work/build.go (tagsFlag.Set)
+	// For compatibility with Go 1.12 and earlier, allow "-tags='a b c'" or even just "-tags='a'".
+	if strings.Contains(s, " ") || strings.Contains(s, "'") {
+		var err error
+		*v, err = splitQuotedFields(s)
+		if *v == nil {
+			*v = []string{}
+		}
+		return err
+	}
+
+	// Starting in Go 1.13, the -tags flag is a comma-separated list of build tags.
+	*v = []string{}
+	for _, s := range strings.Split(s, ",") {
+		if s != "" {
+			*v = append(*v, s)
+		}
 	}
-	return err
+	return nil
 }
 
 func (v *TagsFlag) Get() interface{} { return *v }
 
 func splitQuotedFields(s string) ([]string, error) {
-	// Split fields allowing '' or "" around elements.
-	// Quotes further inside the string do not count.
+	// See $GOROOT/src/cmd/internal/quoted/quoted.go (Split)
+	// This must remain in sync with that logic.
 	var f []string
 	for len(s) > 0 {
 		for len(s) > 0 && isSpaceByte(s[0]) {
@@ -76,5 +94,7 @@ func (v *TagsFlag) String() string {
 }
 
 func isSpaceByte(c byte) bool {
+	// See $GOROOT/src/cmd/internal/quoted/quoted.go (isSpaceByte, Split)
+	// This list must remain in sync with that.
 	return c == ' ' || c == '\t' || c == '\n' || c == '\r'
 }